4th grade plant research project

23 Plant Experiment Ideas

ThoughtCo / Hilary Allison

• Cell Biology
• Weather & Climate
• B.A., Biology, Emory University
• A.S., Nursing, Chattahoochee Technical College

Plants are tremendously crucial to life on Earth. They are the foundation of food chains in almost every ecosystem. Plants also play a significant role in the environment by influencing climate and producing life-giving oxygen.

Plant experiments and studies allow us to learn about plant biology and its potential usage for plants in other fields such as medicine , agriculture , and biotechnology . The following plant experiment ideas provide suggestions for topics to be explored.

Plant Experiment Ideas

• Do magnetic fields affect plant growth?
• Do different colors of light affect the direction of plant growth?
• Do sounds (music, noise, etc.) affect plant growth?
• Do different colors of light affect the rate of photosynthesis ?
• What are the effects of acid rain on plant growth?
• Do household detergents affect plant growth?
• Can plants conduct electricity ?
• Does cigarette smoke affect plant growth?
• Does soil temperature affect root growth?
• Does caffeine affect plant growth?
• Does water salinity affect plant growth?
• Does artificial gravity affect seed germination?
• Does freezing affect seed germination?
• Does burned soil affect seed germination?
• Does seed size affect plant height?
• Does fruit size affect the number of seeds in the fruit?
• Do vitamins or fertilizers promote plant growth?
• Do fertilizers extend plant life during a drought ?
• Does leaf size affect plant transpiration rates?
• Can plant spices inhibit bacterial growth ?
• Do different types of artificial light affect plant growth?
• Does soil pH affect plant growth?
• Do carnivorous plants prefer certain insects?
• Guide to the 6 Kingdoms of Life
• Phases of the Bacterial Growth Curve
• Gram Positive vs. Gram Negative Bacteria
• Animal Studies and School Project Ideas
• Angiosperms
• 10 Facts About Pollen
• Nematoda: Roundworms
• Is Spontaneous Generation Real?
• Parts of a Flowering Plant
• 5 Tricks Plants Use to Lure Pollinators
• Carnivorous Plants
• Mutualism: Symbiotic Relationships
• The Photosynthesis Formula: Turning Sunlight into Energy
• All About Photosynthetic Organisms
• Protista Kingdom of Life
• Common Animal Questions and Answers

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Easy Plant Science Experiments for the Classroom

Working with seeds and leaves can teach your students about much more than capillary action, germination, and photosynthesis. It can provide valuable lessons in caring for living things, collecting data, and using the scientific method.

The following hands-on plant science activities are easy to integrate into your kindergarten, elementary, or middle school classroom. Although we’ve grouped them according to age, some work well with children of all ages and several can be easily adapted for different age groups and abilities.

Some can be done in the course of a single afternoon, others may lead to long-term observations of a plant’s progress or even a class garden that can be transferred outside in the spring.

Science Seedlings for K-2 Learners

Teaching children about how plants work is often a simple a matter of building on their natural curiosity. Your kindergarten and elementary students may have questions about how plants “eat,” “drink,” or grow.

Here are a few simple experiments to start with:

How leaves get water

What leaves need to germinate

How water travels through plants

How leaves breathe

If fresh pine cones are readily available in your area, you might also discuss what pine cones are for, and show your students why they open and close.

K-2 students are also ready to grow and germinate seedlings – beans happen to be easy to germinate and very inexpensive to work with. With some natural light and a wet paper towel, you can germinate seeds in plastic bags so that students can see the gradual changes in the seeds as they opens up.

Some simple experiments with seeds in small plastic cups or egg cartons can also teach students exactly what seeds need in order to grow.

Even at this age, your students can record brief observations such as whether they watered a plant and how tall it has become. Filling in a simple chart like this one to monitor plant growth lets nascent readers and writers practice their literacy skills while being scientists.

Herbs like basil, mint, and thyme work well in classrooms because they grow quickly, as does aloe vera, which requires hardly any maintenance.

Going Beyond Germination in Grades 3–5

Older students can not only handle the responsibility of caring for plants in the classroom, they can also work with more challenging varieties of plants. They can even begin designing experiments by choosing subjects and isolating variables.

For example, they might try sprouting the same species in different types of soils, or do the opposite, and test out a variety of seeds in the soil native to your area.

Growing “spuds in tubs” or “cabbage clones” in the classroom gives your students a taste of traditional agriculture – and they may actually be able to eat what they produce!

Working with plant clones is also an easy way to introduce the notion that different living things reproduce in different ways – a biological fundamental that may very well amaze your students. You could also connect these activities to lessons in history and geography: a unit about Eastern Europe or Ireland, for example.

The way leaves change color in the fall is fascinating no matter how old you are, and discovering the different pigments which make that change possible is a great way for students to begin learning about photosynthesis.

Try out this activity near the start of the school year, when the leaves in your area are likely still green. Then, when the leaves start changing in the fall, make sure to reflect back on the experiment and see if your class could predict what colors their local trees would become.

Branching Out in the Middle Years

Starting in sixth grade, students are ready to truly start experimenting with plants. They can begin using the scientific method to perform and design plant science experiments, and begin exploring the many places where plant science intersects with engineering, chemistry, physics.

Understanding photosynthesis is a key launching point for plant science explorations in high school and beyond. However, all too often photosynthesis is taught as a complex chemical equation, which can be difficult for students to remember or comprehend.

This low-tech experiment with leaf disks has become a classic because it enables students to see and document photosynthesis while it’s happening. It also helps them remember the elements necessary for photosynthesis to occur: light, water, and carbon.

The idea that plants need light is something younger schoolchildren can easily grasp. Older students can develop and deepen that knowledge by experimenting with phototropism: plants’ tendency to grow towards their light source.

Students could conduct experiments to see what color of light different plant species prefer. You could also challenge your them to design and build shoebox mazes for plants to navigate while growing towards the light.

With these experiments, you can either give your students a clear goal and directions to follow, or you can encourage your students to create their own hypotheses and design experiments to test them.

As your students gain more knowledge of biology and ecology, you can incorporate plant science experiments into larger units about the environment. For example, here is a simple experiment in which students test how man-made chemicals affect the growth of algae. Like terrestrial plans, algae depends on photosynthesis, but it also grows relatively quickly, so you’ll be able to see results within only one or two weeks.

This water filtration experiment demonstrates how essential plants are for the welfare of our soil and water. To get started, create three miniature milk-carton landscapes: one with living plants, one with dead leaves and sticks, and one with no plant matter at all. Then, pour water into each of them and harvest whatever “groundwater” drips out. The landscape with plants should have the clearest groundwater of all.

To take this experiment to a higher level, have your students perform a couple of chemical tests on your groundwater using paper test strips. You may be surprised to discover what chemicals the soil contains!

Creating Strong Scientific Roots

Classroom plant science is about much more than basic agriculture. It’s an essential step for children in learning how science works and in becoming good environmental stewards. It can be incredibly rewarding for your students and, through hands-on experience, give them lessons in problem solving, patience, diligence and teamwork that will last a lifetime.

Check out more plant science links over on our Pinterest board , and tell us about your plant science experiments, too. What plant science hypotheses have your students tested? What have you grown in your classroom?

Rebecca Reynandez

One comment on “ easy plant science experiments for the classroom ”.

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Plants Teaching Resources for 4th Grade

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Capillary Action in Plants - Science Experiment Booklet

Observe and record learning about the Capillary Action of Plants with a printable science experiment guidebook.

Exploring Plants - Teaching Slides

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Life Cycle of a Pumpkin Activity Templates

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Plant Adaptations Webquest Activity

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Are you looking for science activities to do with your 4th graders? No sweat. We have you covered. Check out our list of 26 science projects and experiments that you can try with your 4th graders this month.

• Hand-Eye Coordination and Age | All-Science-Fair-Projects.com – Grades 2-5, Use a stopwatch and ping-pong ball to find out how hand-eye coordination changes as children get older.
• What Do Yeast Eat…and How Can You Tell? | Education.com – Grades 2-5, The objective of this project is to examine which foods yeast cells eat.
• How Do Antacids Work? | Biochemistry Discovery Lab – Grades 3-6, Simulate out how antacids work to treat heartburn by using fake stomach enzymes.
• Mice & Music | Hubpages.com – Grades 3-6, Find out if music affects the performance of mice in a maze.
• A Magnetic Primer Designer | Sciencebuddies.org – Grades 3-6 Biology project that utilizes magnets to mimic the process that scientists use to replicate DNA, using the polymerase chain reaction.
• Growing Bacteria in Petri Dishes | Stevespanglerscience.com – Grades 3-6 biology In this science fair project, you must find samples of bacteria from an assortment of surfaces to find the surfaces that are the dirtiest.
• How Does Color Affect Eyesight? | Education.com – Grades 1-5, Find out which colors are easier and more challenging to read at a distance. This super simple project requires volunteers and color charts you can print from the web.
• Effects of Ozone on Plants and Health | Julian’s Science Fair – Grades 4-6, Environmental conditions can dramatically impact plant growth and germination. Does increased ozone stunt germination and plant growth? Grow some plants and find out.
• Making Batteries from Fruits and Vegetables | Sciencebuddies.org – Grades 4-7, Use veggie power to build a simple battery from a variety of vegetables. Which ones are the most powerful?
• How Many Letters? | ScienceBuddies.org – Grades 1-4, How much memory does a computer use to “remember” a series of letters? Find out how much memory a computer uses to remember 1000 letters.
• Jumping For Geodes: Can You Tell the Inside from the Outside? | ScienceBuddies.org Grades 1-4, Can you tell what’s inside a geode from looking at the outside? Learn more out these unique rocks and crack some open to discover the surprises inside.
• How Water Beats Rock | Education.com – Grades 1-5, Discover how water is more potent than rocks.  Experiment with ways that water can break the stone.
• Soil Type and Liquefaction | All-Science-Fair-Projects.com – Grades 1-5, Experiment with sand, clay, and loam and find out which type of soil dissolves most easily.
• Effects of Temperature and Humidity on Static Charges | Education.com – Grades 1-5, Use balloons, a rubber ball, and a scarf to investigate why those socks stick together when you take them out of the dryer and how conditions in the air affect static electricity.
• Dig This: Biodegradation | Education.com – Grades 2-6, How do organic materials become soil? This science experiment measures which materials biodegrade.
• Geology 101 | Education.com – Grades 2-6, Water carries lots of soil and minerals in a creek. In this project, you’ll examine the behavior of water and gravel in creek beds and the formation of sedimentary rocks.
• Geothermal Power Plant Model | Energyquest.ca.gov – Grades 3-6, Use a pinwheel and a can of boiling water to simulate geothermal power production. Determine how to generate the most energy from your “power plant.”
• Egg Substitutes | Sciencebuddies.org – Grades 3-6, Many people avoid eggs because of allergies or diet preferences. But eggs play a vital chemical function in baking and cooking. Evaluate the ability of egg substitutes to mimic their binding, leavening, or thickening properties.
• How Much Water is Required to Cook Pasta? | Sciencebuddies.org – Grades 3-6, We’re used to cooking our pasta in a big pot of boiling water. Do you actually need that much water, time, and energy to cook pasta? Perform some experiments to find out.
• Building the Best Bridge | Education.com – Grades 3-6, This project helps students develop an understanding of architecture and engineering through experimentation of which shapes are the most structurally strong.
• Rubber Bands for Energy | Sciencebuddies.org – Grades 3-6, Put the energy of rubber bands to work and learn about the relationship between potential and kinetic energy.
• Properties of Pendulums | Illinois Institute of Technology – Grades 3-6, Pendulums have been used for timekeeping for hundreds of years. Find out how changes in mass and length affect the oscillation of a pendulum.
• Arch Magic: The Unbreakable Egg | Education.com – Grades 4-7, Tell you, folks, tonight is a good night for an egg dinner. Use the eggshells to explore how arches distribute weight. Demonstrates the power of arches by asking students to pile telephone books on top of eggs without damaging them.
• How a Comet’s Size Affects How Fast It Melts | Sciencebuddies.org – Grades 4-7, Comets are often compared to giant, dirty snowballs, and the comet tail you see in the sky is evidence of melting. In this project, you’ll use figure out how the size of a comet affects its melting rate.
• Make an Electromagnet | Energyquest.ca.gov -Grades 4-7, Learn how to create an electromagnet from batteries, wire, and a knife switch. How does changing to kind of batteries used affect the power of your
• Bombs Away! A Ping Pong Catapult | Science Buddies.org – Grades 4-7, They fly through the air with the greatest of ease. Find ways to put a ping pong ball accurately on target time after time.

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50 Exciting 4th Grade Science Projects and Experiments

Did you know you can make plastic from milk?

Nothing gets kids more excited for science than hands-on experiments! Watch your 4th grade science students’ eyes light up when they try some of these activities. You’ll find physics, biology, engineering, chemistry, and more. These projects are easy to set up and really help drive the learning home. Get ready for some science fun!

To help you find the right 4th grade science projects and activities, we’ve rated them all based on difficulty and materials:

Difficulty:

• Easy: Low or no-prep experiments you can do pretty much any time
• Medium: These take a little more setup or a longer time to complete
• Advanced: Experiments like these take a fairly big commitment of time or effort
• Basic: Simple items you probably already have around the house
• Medium: Items that you might not already have but are easy to get your hands on
• Advanced: These require specialized or more expensive supplies to complete

4th Grade Science Fair Projects

4th grade stem challenge science projects, 4th grade motion and energy science activities.

• More 4th Grade Science Projects and Experiments

These 4th grade experiments also work well as science fair projects. Try changing up the variables to turn it into a real experiment, then form a hypothesis and find out what happens.

Blow unpoppable bubbles

Difficulty: Easy / Materials: Medium

A soap bubble you can hold in your hand? It’s true! A little glycerin makes the soap bubble layers stronger, so you can even toss them gently from person to person.

Learn more: Unpoppable Bubbles Experiment at Learning Resources

Grow crystal names

Difficulty: Easy / Materials: Medium ADVERTISEMENT

No list of 4th grade science projects would be complete without crystals! Kids of all ages love growing crystals, making this an ideal way to learn about supersaturated solutions. The classic experiment gets a new twist when you have kids shape pipe cleaners into their own names first.

Learn more: Crystal Letters at Playdough to Plato

Grow bacteria in petri dishes

Difficulty: Medium / Materials: Medium

Your students will truly feel like scientists when they perform this classic experiment. They’ll prep the dishes with agar, swab different surfaces, and see what bacteria they grow. It’s gross science, but it’s also easy and impressive.

Learn more: Growing Bacteria at Steve Spangler Science

See coastal erosion in action

Here’s a cool experiment to include in your unit on oceans. Build a miniature coastline, then see how wave action erodes the shore.

Learn more: Erosion Experiment at Little Bins for Little Hands

Erupt a lemon volcano

Difficulty: Easy / Materials: Basic

Early chemistry experiments with acids and bases are always a lot of fun. This one uses the natural acids of lemon juice and adds a little food coloring to up the wow factor.

Learn more: Lemon Volcano at STEAM Powered Family

Sink and float to explore density

Adding items like salt or sugar to water changes its density, as does the temperature itself. Turn this into a 4th grade science fair project by experimenting with different solutions and forming hypotheses about the results.

Learn more: Salt Water Density at Science Kiddo

Discover a density rainbow

Difficulty: Medium / Materials: Basic

Colorful, simple, and impressive: It’s the trifecta of 4th grade science experiments! Wow your students by layering colored sugar water as you learn about density, adhesion, and cohesion.

Transform milk into plastic

Plastic seems incredibly modern, but people have been making casein plastic from milk for centuries. In this 4th grade science project, students experiment to create the formula for the best milk plastic. They’ll be amazed at the results!

Simulate an earthquake

The ground under our feet may feel solid, but an earthquake changes that pretty quickly. Use Jell-O to simulate the Earth’s crust, then see if you can build an earthquake-proof structure for a practical and fascinating 4th grade science fair project.

Learn more: Earthquake Simulation at Teaching Science

Test Sharpie solubility

Find out if Sharpie markers are really permanent with this 4th grade science project that uses the scientific method to explore solutes and solvents.

Learn more: Sharpie Solubility at Around the Kampfire

Find out if mood rings really work

Apply the rigors of the scientific method to mood rings ! Find out what makes mood rings change color, then see if they really reflect a person’s mood.

Learn more: Mood Rings Validity Test at Education.com

Create a new plant or animal

Kids will really get into this project, indulging their creativity as they invent a plant or animal that’s never been seen before. They’ll need to be able to explain the biology behind it all, though, making this an in-depth project you can tailor to any class.

Learn more: Create an Organism at I Love 2 Teach

Investigate decomposition

Difficulty: Easy / Materials: Easy

Yup, it’s gross … so kids will love it! Seal food items in a plastic bag and experiment to see what factors affect their decomposition, helped along by a heaping dose of mold.

Learn more: Decomposition at Mystery Science

Assemble a lung model

With just a few supplies including balloons and a plastic bottle, you can make an impressive working model of human lungs. This makes a very cool 4th grade science fair project.

Explore the causes of tooth decay

They hear it from their parents all the time, but this experiment will prove to your students once and for all what can happen to their teeth when exposed to different drinks such as soda and milk. This is one of those classic 4th grade science fair projects every kid should try.

For students who love to tinker, STEM challenges can spark incredible 4th grade science fair projects. Here are some of our favorites for this age group.

Engineer a drinking-straw roller coaster

STEM challenges are always a hit with kids. We love this one, which only requires basic supplies like drinking straws . ( Get more 4th grade STEM challenges here. )

Learn more: Drinking Straw Roller Coaster at Frugal Fun for Boys and Girls

Make a wigglebot

Who knew electricity could be so adorable? Explore the science behind batteries and motors by creating a simple “wigglebot.” Experiment with weights to throw the motor off balance and create fun designs.

Learn more: Wigglebot at Research Parent

Construct a working flashlight

You’ll only need a few supplies to guide your students in building their own LED flashlights. They’ll learn how electricity travels and the way circuits work. The slideshow available through the link makes this lesson a breeze for teachers too.

Learn more: DIY Flashlight at Mystery Science

Build a hovercraft

It’s not exactly the same model the military uses, but this simple hovercraft is a lot easier to build. An old CD and a balloon help demonstrate air pressure and friction in this fun 4th grade science experiment.

Learn more: DIY Hovercraft at Education.com

Create a smartphone projector

No projector in your classroom yet? No problem! Have your students help you construct one for your smartphone using a cardboard box and large magnifying glass . They’ll learn about convex lenses and how the brain processes images too.

Learn more: DIY Smartphone Projector at The STEM Laboratory

Set up a pulley system

The science of machines never fails to fascinate kids. In this experiment, they’ll design their own pulley system to make it easier to lift an object.

Learn more: DIY Pulley at 123 Homeschool 4 Me

Design a working elevator

Engineering activities make for amazing hands-on learning. Challenge your 4th grade students to build an elevator that can safely lift a certain amount of weight.

Make a model seismometer

Explore the science of seismology and learn how scientists study earthquakes and their effects. This model seismometer is easy to build and fun to experiment with.

Learn more: Model Seismometer at Science Sparks

Conduct an egg drop

Here’s one more classic to add to our list of 4th grade science experiments: the egg drop! The great thing about this project is that kids can do it at any age, with different materials and heights to mix it up. Hit the link below to get an egg drop project designed just for 4th graders.

Learn more: Egg Drop Challenge Ideas

Demonstrate Newton’s laws of motion with balloon rockets

Who doesn’t love balloon rockets?! Your students will have a blast(off) displaying Newton’s third law of motion while learning about physics.

Many 4th grade science standards include units on energy and motion. These energy science activities offer cool hands-on ways to spice up your classroom lessons.

Flick marbles to learn transfer of energy

This experiment is a bit of a thinker: What will happen when one moving marble hits several stationary marbles sitting in a row? Flick the first marble and find out!

Learn more: Marble Energy Transfer at Frugal Fun for Boys and Girls

See energy transfer in action with sports balls

Place a tennis ball on top of a basketball and bounce them together to see how energy transfers from one object to another. This one is very easy, and kids will love seeing how high they can get the balls to bounce!

Go an on energy scavenger hunt

Emphasize the fact that energy is all around us in one form or another with this easy, free printable energy science activity. For a more advanced version, help students identify each kind of energy (kinetic, stored, heat, etc.) they find.

Learn more: Energy Scavenger Hunt at The Science Penguin

See a heat-powered windmill demonstrate convection

Heat rises, and its interaction with cooler air creates convection currents. Find out how we can put convection to work for us with this 4th grade science craft project.

Capture waves in a bottle

Here’s a quick and easy way to show wave action in a no-mess way. You don’t need to add a little ship to the bottle, but it does make it more fun!

Learn more: Waves in a Bottle at What I Have Learned Teaching

Assemble a wave machine

Turn this one into a class cooperative activity, or try it as a science fair project idea. Either way, it’s an incredibly fascinating way to demonstrate the energy science of waves.

Use a Slinky to demonstrate types of waves

A Slinky is more than just a toy—it’s also a terrific science manipulative! Use it to see waves in motion, both longitudinal and transverse.

Watch gravity beads prove Newton’s laws

You’ll need a loooooooong string of beads for this experiment. Make your own by taping dollar-store strings together, or buy a long bead garland . Pile them in a cup and get the beads going; it’s fascinating to watch inertia and gravity at work.

Learn more: Gravity Beads at Teach Beside Me

Spin marble tops to learn about inertia

Glue together marbles in a variety of pyramidal patterns to form tops, then form hypotheses about which will spin best. Afterwards, kids will have fun new toys to play with!

Learn more: Marble Tops at KidsActivities.com

Visualize the second law of motion with soda cans

Newton’s second law, concerning acceleration, force, and mass, can be a little hard to understand. This easy 4th grade science demo makes it a little easier to visualize.

More 4th Grade Science Projects and Activities

Use these cool science experiments to encourage a love of science, at home or in the classroom!

Measure a magnet’s attraction force

Fourth grade science students already know that magnets attract metal objects. In this experiment, they’ll measure to see how close a magnet needs to be to an object for the attraction to work. Mix things up with different sizes of magnets and objects of various weights.

Learn more: Magnet Measurements at Ashleigh’s Education Journey

See light refraction in action

This seems more like a magic trick, but we promise it’s science! Make colors seem to appear and disappear, change numbers into letters, and more.

Learn more: Light Refraction at Ronyes Tech

“Draw” on water with dry-erase marker

This is another one of those mind-blowing science demos that kids will want to try over and over again. Draw on a shallow bowl or plate with dry-erase markers , then slowly add water. The marker (which is insoluble in water) will float to the top!

Paint with sunscreen

Prove that sunscreen really does provide protection from harmful UV rays. Turn this into a full-blown experiment by trying different SPFs or comparing it to other creams or lotions without SPF.

Learn more: Paint With Sunscreen at Team Cartwright

Become human sundials

Choose a sunny day and grab some sidewalk chalk—your students are about to become sundials! They’ll practice measuring skills and learn about the movement of the sun across the sky.

Learn more: Human Sundial at Rhythms of Play

Mine for chocolate chips

If you’re learning about mineral resources, this quick hands-on activity is an interesting way to explore the effects of mining. Kids have two minutes to find as many chocolate chips as they can in a cookie. Will they smash it up and destroy it entirely? Pick them out one by one? This experiment can lead to intriguing discussions.

Learn more: Mining for Chocolate Chips at Sarah’s STEM Stuff

Assemble an edible DNA model

Use licorice sticks, four different-colored candies or fruits, and toothpicks to build an edible strand of DNA. Learn about chemical bonds and the helix shape, then eat your creation!

Learn more: Edible DNA Model at wikiHow

Layer an edible soil model

Digging in the dirt is fun, but it’s even more fun when you can eat the dirt when you’re finished! Create edible soil-layer models, complete with gummy worms, for a simple earth science project. ( Find more edible science projects here. )

Learn more: Edible Soil Layers at Super Teacher Blog

Turn a penny green

Experiment with simple chemical reactions as you turn pennies green using vinegar. (Don’t forget to tell students that the Statue of Liberty is green for this very same reason!)

Learn more: Penny Reactions at Buggy and Buddy

Use marshmallows to explore Boyle’s law

Seeing Boyle’s law (which relates pressure and volume of gasses) in action makes it a little easier to understand and remember. This simple 4th grade science experiment uses marshmallows to make a great visual.

Learn more: Boyle’s Law at Hojo’s Teaching Adventures

Form ocean currents

Learning about oceanography? Demonstrate how ocean currents form using warm and cold water (and a few plastic sea creatures for extra fun!).

Learn more: Ocean Currents at Life Over C’s

Understand the impact of non-renewable resources

This is a neat Earth Day activity . Discuss the differences between renewable and non-renewable resources, then have your class form “companies” to “mine” non-renewable resources. As they compete, they’ll see how quickly the resources are used. It’s a great tie-in to energy conservation discussions.

Learn more: Non-Renewable Resources at The Owl Teacher

Explore blood components

Use simple kitchen supplies to create a jar full of “blood” that includes plasma, platelets, red blood cells, and white blood cells. (You can even snack on the blood cells along the way!)

Learn more: Blood Model at Almost Supermom

Create cool colors with candy

Learn about diffusion in the sweetest way! Grab a bag of Skittles for this quick and easy 4th grade science project.

Wow them with glowing water

Your students will ooh and aah at the result of this exploratory way to show phosphors in action with a black light, different types of water, and a highlighter. The results of this experiment might surprise both you and your students!

Learn more: Glowing Water Experiment at Cool Science Experiments Headquarters

Keep the STEM excitement going with these 25 Fantastic Free 4th Grade Math Games .

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25 Fun and Easy Fourth Grade STEM Challenges (Free Printable!)

Hands-on fun that also helps them grow. Continue Reading

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4th Grade Plant Science Fair Projects

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Microwaves and Plants

Photo ©2007 Tim Patterson, Flickr You're probably wondering what kind of sc...

Phototropism: Why Do Plants Grow Toward Light?

For those elementary students interested in botany, this cool experiment fro...

Multicolored Flowers

Photo © 2008 Subramanian Kabilan, Flickr This science experiment, designed ...

The Effect of Acid Rain on Aquatic Life

Photo © 2005 Rick Smit, Flickr Like smoking, pollution has "second-hand" ef...

Oxygen in Plant Respiration

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Research Lays Groundwork for Future Fertilizers

A North Carolina State University research team that set out four years ago to create the fertilizer of the future — one that was more energy efficient, environmentally sustainable and profitable for farmers than today’s commercial fertilizers — has laid important groundwork to transform the production and use of fertilizer in the United States and beyond.

The interdisciplinary Fertilizer of the Future project team was awarded seed funding in 2020 from the university’s Game-Changing Research Incentive Program for Plant Sciences Initiative , or GRIP4PSI. GRIP4PSI’s goal was to kickstart the kind of problem-solving, interdisciplinary agricultural research that advocates who pushed for the North Carolina Plant Sciences Initiative were aiming for.

GRIP4PSI funding has leveraged new grants and industry partnerships for members of the Fertilizer of the Future team, and project leader Katharina Stapelmann , of the Department of Nuclear Engineering, said such advancements could prove key to pushing the vision forward.

Taking an interdisciplinary approach

At the outset of the Fertilizer of the Future project in 2020, Stapelmann’s 12-member team from nine departments and three NC State colleges envisioned using plasma technology, bacteria and fertigation to enhance crop production.

For her part, Stapelmann focused on treating water with plasma to produce nitrates that plants could use to fuel their growth. Plasma is a partly ionized gas that makes up most of the visible universe.

Meanwhile, Douglas Call , of the Department of Civil, Construction and Environmental Engineering, and Amy Grunden, of the Department of Plant and Microbial Biology, focused on increasing the amount of ammonium that a bacterium from the genus Geobacter could convert from nitrogen in the air.

Chadi Sayde , of the Department of Biological and Agricultural Engineering, led an effort to develop and test sensors for monitoring the water and nitrogen content of soil. Sensor development was a key to developing a precision fertigation system that would incorporate the bacteria-produced ammonium and the plasma-treated water, delivering nitrogen exactly when plants needed it.

Obstacles and accomplishments

In its early work, the team faced significant obstacles: among them, the COVID-19 pandemic and the challenge of coming up with a soil mixture that could be used in replicable experiments. And Stapelmann says that when the project’s funding ended in 2023, the researchers found that their nitrate sensors weren’t working as well as they wanted them to, the plasma device they were using to treat water needed upscaling, bacteria weren’t fixing as much ammonia as they’d believe they would, and time ran out on the funding before they could pursue fertigation studies.

Still, there was plenty of good news:

• Early on, the team published a well-cited paper in the journal Plasma Processes and Polymers. The report summarized how plasma technology is being used in agriculture and provided context to design plasma-based fertilization strategies in the future.
• Now-graduated biological and environmental engineering Ph.D. student Mark Poole developed a CRISPR gene-editing system for Geobacter that Call and Grunden’s team is now using to make changes to the strain to allow it to make even more ammonia. That team’s work is part of the larger, $6.6 million Biocatalyst Interactions with Gases Collaboration funded by the Novo Nordisk Foundation and headed by Sonja Salmon of the Wilson College of Textiles.
• Biological and agricultural engineering Ph.D. student Riley Lawson won a Fulbright Scholarship and will spend the next academic year in France working to develop an enzyme-based sensor system to detect ammonia, urea and nitrate in soils in real time.
• And Stapelmann has secured grant funding to continue basic research to explore related issues in plasma physics and developed a partnership with a company that wants to use water-treated plasma for fertilizer in contained growing environments.

Based on these and other project successes, Stapelmann believes the team’s original vision of a more sustainable, efficient system for fertilizing crops could one day be realized.

“When we started out, we all thought our technologies could be developed further, quicker,” she says. “I think with a little bit more time and more funding, we could still get there. We learned a lot during the project, and we now have a great team working across disciplines. I think that puts us in a better position to get more funding for parts of the project.”

More From N.C. Plant Sciences Initiative

Toward Better Plant Disease Prediction 

Engaging Youth in Agriculture, Both Near and Far 

Partnership Seeds Two Agricultural Sensor Projects 

• Research article
• Open access
• Published: 22 August 2024

A systematic review and meta-analysis of randomized trials of substituting soymilk for cow’s milk and intermediate cardiometabolic outcomes: understanding the impact of dairy alternatives in the transition to plant-based diets on cardiometabolic health

• M. N. Erlich 1 , 2 ,
• D. Ghidanac 1 , 2 ,
• S. Blanco Mejia 1 , 2 ,
• T. A. Khan 1 , 2 ,
• L. Chiavaroli 1 , 2 , 3 ,
• A. Zurbau 1 , 2 ,
• S. Ayoub-Charette 1 , 2 ,
• A. Almneni 4 ,
• M. Messina 5 ,
• L. A. Leiter 1 , 2 , 3 , 6 , 7 ,
• R. P. Bazinet 1 ,
• D. J. A. Jenkins 1 , 2 , 3 , 6 , 7 ,
• C. W. C. Kendall 1 , 2 , 8 &
• J. L. Sievenpiper 1 , 2 , 3 , 6 , 7  

BMC Medicine volume  22 , Article number:  336 ( 2024 ) Cite this article

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Dietary guidelines recommend a shift to plant-based diets. Fortified soymilk, a prototypical plant protein food used in the transition to plant-based diets, usually contains added sugars to match the sweetness of cow’s milk and is classified as an ultra-processed food. Whether soymilk can replace minimally processed cow’s milk without the adverse cardiometabolic effects attributed to added sugars and ultra-processed foods remains unclear. We conducted a systematic review and meta-analysis of randomized controlled trials, to assess the effect of substituting soymilk for cow’s milk and its modification by added sugars (sweetened versus unsweetened) on intermediate cardiometabolic outcomes.

MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched (through June 2024) for randomized controlled trials of ≥ 3 weeks in adults. Outcomes included established markers of blood lipids, glycemic control, blood pressure, inflammation, adiposity, renal disease, uric acid, and non-alcoholic fatty liver disease. Two independent reviewers extracted data and assessed risk of bias. The certainty of evidence was assessed using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). A sub-study of lactose versus sucrose outside of a dairy-like matrix was conducted to explore the role of sweetened soymilk which followed the same methodology.

Eligibility criteria were met by 17 trials ( n  = 504 adults with a range of health statuses), assessing the effect of a median daily dose of 500 mL of soymilk (22 g soy protein and 17.2 g or 6.9 g/250 mL added sugars) in substitution for 500 mL of cow’s milk (24 g milk protein and 24 g or 12 g/250 mL total sugars as lactose) on 19 intermediate outcomes. The substitution of soymilk for cow’s milk resulted in moderate reductions in non-HDL-C (mean difference, − 0.26 mmol/L [95% confidence interval, − 0.43 to − 0.10]), systolic blood pressure (− 8.00 mmHg [− 14.89 to − 1.11]), and diastolic blood pressure (− 4.74 mmHg [− 9.17 to − 0.31]); small important reductions in LDL-C (− 0.19 mmol/L [− 0.29 to − 0.09]) and c-reactive protein (CRP) (− 0.82 mg/L [− 1.26 to − 0.37]); and trivial increases in HDL-C (0.05 mmol/L [0.00 to 0.09]). No other outcomes showed differences. There was no meaningful effect modification by added sugars across outcomes. The certainty of evidence was high for LDL-C and non-HDL-C; moderate for systolic blood pressure, diastolic blood pressure, CRP, and HDL-C; and generally moderate-to-low for all other outcomes. We could not conduct the sub-study of the effect of lactose versus added sugars, as no eligible trials could be identified.

Conclusions

Current evidence provides a good indication that replacing cow’s milk with soymilk (including sweetened soymilk) does not adversely affect established cardiometabolic risk factors and may result in advantages for blood lipids, blood pressure, and inflammation in adults with a mix of health statuses. The classification of plant-based dairy alternatives such as soymilk as ultra-processed may be misleading as it relates to their cardiometabolic effects and may need to be reconsidered in the transition to plant-based diets.

Trial registration

ClinicalTrials.gov identifier, NCT05637866.

Peer Review reports

Major dietary guidelines recommend a shift to plant-based diets for public and planetary health [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ] , while recommending simultaneous reductions in ultra-processed foods [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The shift to plant-based diets has resulted in an explosion of dairy, meat, and egg alternatives with plant protein foods projected to reach almost 10% of the global protein market by 2030 [ 9 ]. Although these foods can aid in the transition to plant-based diets, food classification systems such as the World Health Organization (WHO)-endorsed NOVA classification system classify them as ultra-processed foods to be avoided [ 10 ].

Dairy alternatives are an important example of a food category at the crossroads of these competing recommendations. School milk programs provide > 150 million servings of cow’s milk to children worldwide [ 11 ]. These programs are in addition to the food service and procurement policies of public institutions such as schools, universities, hospitals, long-term care homes, and prisons. Many of these programs and policies do not allow for the free replacement of cow’s milk with nutrient-dense plant milks [ 12 , 13 ]. Although the Dietary Guidelines for Americans [ 1 ], Canada’s Food Guide [ 3 ], and several European food-based dietary guidelines [ 14 ] recognize fortified soymilk [ 1 ] as nutritionally equivalent to cow’s milk, school nutrition programs in the United States (US) [ 12 ] and Europe [ 13 ] only provide funding for cow’s milk. There is a bipartisan bill before the US congress to change this policy and provide funding for fortified soymilk [ 15 ]. A major barrier to the use of fortified soymilk is that it contains added sugars to match the sweetness of cow’s milk at a level which would disqualify it from meeting the Food and Drug Administration’s proposed definition of “healthy” [ 16 ] (although its total sugar content is usually ~ 60% less than that of cow’s milk given the higher sweetness intensity of sucrose vs lactose) [ 17 ] and is classified (irrespective of its sugar content) as an ultra-processed food to be avoided [ 10 , 18 ]. Cow’s milk, on the other hand, enjoys classification as a “healthy,” minimally processed food to be encouraged [ 10 , 18 ].

As industry innovates in response to the growing demand and policy makers develop public health nutrition policies and programs in response to the evolving dietary guidance for more plant-based diets, it is important to understand whether nutrient-dense ultra-processed plant protein foods can replace minimally processed dairy foods without the adverse cardiometabolic effects attributed to added sugars and ultra-processed foods. We conducted a systematic review and meta-analysis of randomized controlled trials of the effect of substituting soymilk for minimally processed cow’s milk and its modification by added sugars (sweetened versus unsweetened) on intermediate cardiometabolic outcomes as a basis for understanding the role of nutrient-dense ultra-processed plant protein foods in the transition to plant-based diets.

We followed the Cochrane Handbook for Systematic Reviews of Interventions to conduct this systematic review and meta-analysis and reported our results by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines [ 19 , 20 ] (Additional file 1 : Table 1). To explore whether added sugars mediate any effects observed in sweetened soymilk studies, we conducted an additional systematic review and meta-analysis sub-study. This separate investigation followed the same protocol and methodology as our main study. It focused on controlled trials examining the impact of lactose in isocaloric comparisons with fructose-containing sugars (such as sucrose, high-fructose corn syrup [HFCS], or fructose) when not included in a dairy-like matrix, on all outcomes in the main study. The protocol is registered at ClinicalTrials.gov (NCT05637866).

Data sources and search strategy

We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials databases through June 2024. The detailed search strategies for the main study and sub-study were based on validated search terms [ 21 ] (Additional file 1 : Tables 2 and 4). Manual searches of the reference lists of included studies supplemented the systematic search.

Study selection

The main study included randomized controlled trials in human adults with any health status. Included trials had a study duration of ≥ 3 weeks and investigated the effects of soymilk compared with cow’s milk in energy matched conditions on intermediate cardiometabolic outcomes (Additional file 1 : Table 3). Trials that included other comparators that were not cow’s milk or had no viable outcome data were excluded. No restrictions were placed on language. For the sub-study, we included controlled trials involving adults of all health statuses that had a study duration of ≥ 3 weeks and investigated the effects of added sugars compared with lactose on the same intermediate cardiometabolic outcomes (Additional file 1 : Table 5).

Data extraction

A minimum of two investigators (ME, DG, SBM, AA) independently extracted relevant data from eligible studies. Extracted data included study design, sample size, sample characteristics (age, body mass index [BMI], sex, health status), intervention characteristics (soymilk volume, total sugars content, soy protein dose), control characteristics (cow’s milk volume, total sugars content, milk protein dose, milk fat content), baseline outcome levels, background diet, follow-up duration, setting, funding sources, and outcome data. The authors were contacted for missing outcome data when it was indicated that a relevant outcome was measured but not reported. Graphically presented data were extracted from figures using Plot Digitizer [ 22 ].

Outcomes for the main study and sub-study included blood lipids (low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], non-high-density lipoprotein cholesterol [non-HDL-C], triglycerides, and apolipoprotein B [ApoB]), glycemic control (hemoglobin A1c [HbA1c], fasting plasma glucose, 2-h postprandial glucose, fasting insulin, and plasma glucose area under the curve [PG-AUC]), blood pressure (systolic blood pressure and diastolic blood pressure), inflammation (c-reactive protein [CRP]), adiposity (body weight, BMI, body fat, and waist circumference), kidney function and structure (creatinine, creatinine clearance, glomerular filtration rate [GFR], estimated glomerular filtration rate [eGFR], albuminuria, and albumin-creatinine ratio [ACR]), uric acid, and non-alcoholic fatty liver disease (NAFLD) (intrahepatocellular lipid [IHCL], alanine transaminase [ALT], aspartate aminotransferase [AST], and fatty liver index).

Mean differences (MDs) between the intervention and control arm and respective standard errors were extracted for each trial. If these were not provided, they were derived from available data using published formulas [ 19 ]. Mean pairwise difference in change-from-baseline values were preferred over end values. When median data was provided, they were converted to mean data with corresponding variances using methods developed by McGrath et al. [ 23 ]. When no variance data was available, the standard deviation of the MDs was borrowed from a trial similar in size, participants, and nature of intervention. All disagreements were reconciled by consensus or with a senior reviewer (JLS).

Risk of bias assessment

Included studies were assessed for the risk of bias independently and in duplicate by at least two investigators (ME, DG, SBM, AA) using the Cochrane Risk of Bias (ROB) 2 Tool [ 24 ]. The assessment was performed across six domains of bias (randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, selection of the reported result, and overall bias). Crossover studies were assessed for an additional domain of bias (risk of bias arising from period or carryover effects). The ROB for each domain was assessed as “low” (plausible bias unlikely to seriously alter the results), “high” (plausible bias that seriously weakens confidence in results), or “some concern” (plausible bias that raises some doubt about the results). Reviewer discrepancies were resolved by consensus or arbitration by a senior investigator (JLS).

Statistical analysis

STATA (version 17; StataCorp LP, College Station, TX) was used for all analyses for the main study and sub-study. The principal effect measures were the mean pair-wise differences in change from baseline (or alternatively, end differences) between the intervention arm providing the soymilk and the cow’s milk comparator/control arm in each trial (significance at P MD  < 0.05). Results are reported as MDs with 95% confidence intervals (95% CI). As one of our primary research questions relates to the role of added sugars as a mediator in any observed differences between soymilk and cow’s milk, we stratified results by the presence of added sugars in the soymilk (sweetened versus unsweetened) and assessed effect modification by this variable on pooled estimates. Data were pooled using the generic inverse variance method with DerSimonian and Laird random effect models [ 25 ]. Fixed effects were used when less than five trials were available for an outcome [ 26 ]. A paired analysis was applied for crossover designs and for within-individual correlation coefficient between treatment of 0.5 as described by Elbourne et al. [ 27 , 28 ].

Heterogeneity was assessed using the Cochran’s Q statistic and quantified using the I 2 statistic, where I 2  ≥ 50% and P Q  < 0.10 were used as evidence of substantial heterogeneity [ 19 ]. Potential sources of heterogeneity were explored using sensitivity analyses. Sensitivity analyses were done via two methods. We conducted an influence analysis by systematically removing one trial at a time and recalculating the overall effect estimate and heterogeneity. A trial was considered influential if its removal explained the substantial heterogeneity or altered the direction, magnitude, or significance of the summary estimate. To determine whether the overall summary estimates were robust to the use of an assumed correlation coefficient for crossover trials, we conducted a second sensitivity analysis by using correlation coefficients of 0.25 and 0.75. If ≥ 10 trials were available, meta-regression analyses were used to assess the significance of each subgroup categorically and when possible, continuously (significance at P  < 0.05). A priori subgroup analyses included soy protein dose, follow-up duration, baseline outcome levels, comparator, design, age, health status, funding, and risk of bias.

If ≥ 6 trials are available [ 29 ], dose–response analyses were performed using meta-regression to assess linear (by generalized least squares trend (GLST) estimation models) and non-linear spline curve modeling (by MKSPLINE procedure) dose–response gradients (significance at P  < 0.05).

If ≥ 10 studies were available, publication bias was assessed by inspection of contour-enhanced funnel plots and formal testing with Egger’s and Begg’s tests (significance at P  < 0.10) [ 30 , 31 , 32 ]. If evidence of publication bias was suspected, the Duval and Tweedie trim-and-fill method was performed to adjust for funnel plot asymmetry by imputing missing study data and assess for small-study effects [ 33 ].

Certainty of evidence

The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess the certainty of evidence. The GRADE Handbook and GRADEpro V.3.2 software were used [ 34 , 35 ]. A minimum of two investigators (ME, DG, SBM) independently performed GRADE assessments for each outcome [ 36 ]. Discrepancies were resolved by consensus or arbitration by the senior author (JLS). The overall certainty of evidence was graded as either high, moderate, low, or very low. Randomized trials are initially graded as high by default and then downgraded or upgraded based on prespecified criteria. Reasons for downgrading the evidence included study limitations (risk of bias assessed by the Cochrane ROB Tool), inconsistency of results (substantial unexplained interstudy heterogeneity, I 2  > 50% and P Q  < 0.10), indirectness of evidence (presence of factors that limit the generalizability of the results), imprecision (the 95% CI for effect estimates overlap with the MID for benefit or harm), and publication bias (evidence of small-study effects). The evidence was upgraded if a significant dose–response gradient was detected. We defined the importance of the magnitude of the pooled effect estimates using prespecified MIDs (Additional file 1 : Table 6) with GRADE guidance [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ] according to five levels: very large (≥ 10 MID); large (≥ 5 MID); moderate (≥ 2 MID); small important (≥ 1 MID); and trivial/unimportant (< 1 MID) effects.

Search results

Figure 1 in Appendix shows the flow of the literature for the main analysis. We identified 522 reports through database and manual searches. A total of 17 reports [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 ] met the inclusion criteria and contained data for LDL (10 trials, n  = 312), HDL-C (8 trials, n  = 271), non-HDL-C (7 trials, n  = 243), triglycerides (9 trials, n  = 278), HbA1c (1 trial, n  = 25), fasting plasma glucose (5 trials, n  = 147), 2-h plasma glucose (1 trial, n  = 28), fasting insulin (4 trials, n  = 119), systolic blood pressure (5 trials, n  = 158), diastolic blood pressure (5 trials, n  = 158), CRP (5 trials, n  = 147), body weight (6 trials, n  = 163), BMI (6 trials, n  = 173), body fat (1 trial, n  = 43), waist circumference (3 trials, n  = 90), creatinine (1 trial, n  = 25), eGFR (1 trial, n  = 25), ALT (1 trial, n  = 24), and AST (1 trial, n  = 24) involving 504 participants. No trials were available for ApoB, PG-AUC, creatinine clearance, eGFR, albuminuria, ACR, uric acid, IHCL, or fatty liver index.

Additional file 1 : Fig. 1 shows the flow of literature for the sub-study. We identified 1010 reports through database and manual searches. After excluding 305 duplicates, a total of 705 reports were reviewed by title and abstract. No reports met the inclusion criteria and therefore no data was available for analysis.

Trial characteristics

Table 1 shows the characteristics of the included trials. The trials were conducted in a variety of locations, with most conducted in Iran (7/17 trials, 41%), followed by the US (3/17 trials, 18%), Italy (2/17 trials, 12%), Brazil (1/17 trials, 6%), Scotland (1/17 trials, 6%), Sweden (1/17 trials, 6%), Spain (1/17 trials, 6%), and Australia (1/17 trials, 6%). All trials took place in outpatient settings (17/17, 100%). The median trial size was 25 participants (range, 7–60 participants). The median age of the participants was 48.5 years (range, 20–70 years) and the median BMI was 27.9 kg/m 2 (range, 20–31.1 kg/m 2 ). The trials included participants with hypercholesterolemia (4/17 trials, 25%), overweight or obesity (4/17 trials, 25%), type 2 diabetes (2/17 trials, 12%), hypertension (1/17 trials, 6%), rheumatoid arthritis (1/17 trials, 6%), or were healthy (3/17 trials, 18%) or post-menopausal (2/17 trials, 12%). Both trials with crossover design (10/17 trials, 59%) and parallel design (7/17 trials, 41%) were included. The intervention included sweetened (11/17 trials, 65%) and unsweetened (6/17 trials, 35%) soymilk.

The median soymilk dose was 500 mL/day (range, 240–1000 mL/day) with a median soy protein of 22 g/day (range, 2.5–70 g/day) or 6.6 g/250 mL (range, 2.6–35 g/250 mL) and median total (added) sugars of 17.2 g/day (range, 4.0–32 g/day) or 6.9 g/250 mL (range, 1–16 g/250 mL) in the sweetened soymilk. The comparators included skim (0% milk fat) (2/17 trials, 12%), low-fat (1% milk fat) (4/17 trials, 24%), reduced fat (1.5–2.5% milk fat) (7/17 trials, 41%), and whole (3% milk fat) (1/17 trials, 6%) cow’s milk. Three trials did not report the milk fat content of cow’s milk used. The median cow’s milk dose was 500 mL/day (range, 236–1000 mL/day) with a median milk protein of 24 g/day (range, 3.3–70 g/day) or 8.3 g/250 mL (range, 3.4–35 g/250 mL) and median total (lactose) sugars of 24 g/day (range, 11.5–49.2 g/day) or 12 g/250 mL (range, 10.8–12.8 g/250 mL). The median study duration was 4 weeks (range, 4–16 weeks). The trials received funding from industry (1/17 trials, 6%), agency (8/17 trials, 47%), both industry and agency (4/16 trials, 25%), or they did not report the funding source (4/17 trials, 24%).

Additional file 1 : Fig. 2 shows the ROB assessments of the included trials. Two trials were assessed as having some concerns from period or carryover effects: Bricarello et al. [ 53 ] and Steele [ 67 ]. All other trials were judged as having an overall low risk of bias. There was no evidence of serious risk of bias across the included trials.

Markers of blood lipids

Figure 2 and Additional file 1 : Figs. 3–6 show the effect of substituting soymilk for cow’s milk on markers of blood lipids. The substitution resulted in a small important reduction in LDL-C (10 trials; MD: − 0.19 mmol/L; 95% CI: − 0.29 to − 0.09 mmol/L; P MD  < 0.001; no heterogeneity: I 2  = 0.0%; P Q  = 0.823), a trivial increase in HDL-C (8 trials; MD: 0.05 mmol/L; 95% CI: 0.00 to 0.09 mmol/L; P MD  = 0.036; no heterogeneity: I 2  = 0.0%; P Q  = 0.053), a moderate reduction in non-HDL-C (7 trials; MD: − 0.26 mmol/L; 95% CI: − 0.43 to − 0.10 mmol/L; P MD  = 0.002; no heterogeneity: I 2  = 0.0%; P Q  = 0.977), and no effect on triglycerides. There were no interactions by added sugars in soymilk for any blood lipid markers ( P  = 0.49–0.821).

Markers of glycemic control

Figure 2 and Additional file 1 : Figs. 7–10 show the effect of substituting soymilk for cow’s milk on markers of glycemic control. The substitution had no effect on HbA1c, fasting plasma glucose, 2-h plasma glucose, or fasting insulin. There was no interaction by added sugars in soymilk for fasting plasma glucose ( P  = 0.747) but there was an interaction for fasting insulin ( P  = 0.026), where a lack of effect remained in both groups with neither the sweetened soymilk (non-significant increasing effect) nor the unsweetened soymilk (non-significant decreasing effect) showing an effect on fasting insulin. We could not assess this interaction for HbA1c or 2-h plasma glucose, as there was only one trial available for each outcome.

Blood pressure

Figure 2 and Additional file 1 : Figs. 11 and 12 show the effect of substituting soymilk for cow’s milk on blood pressure. The substitution resulted in a moderate reduction in both systolic blood pressure (5 trials; MD: − 8.00 mmHg; 95% CI: − 14.89 to − 1.11 mmHg; P MD  = 0.023; substantial heterogeneity: I 2  = 86.89%; P Q  ≤ 0.001) and diastolic blood pressure (5 trials; MD: − 4.74 mmHg; 95% CI: − 9.17 to − 0.31 mmHg; P MD  = 0.036; substantial heterogeneity: I 2  = 77.3%; P Q  = 0.001). There were no interactions by added sugars in soymilk for blood pressure ( P  = 0.747 and 0.964).

Markers of inflammation

Figure 2 and Additional file 1 : Fig. 13 show the effect of substituting soymilk for cow’s milk on markers of inflammation. The substitution resulted in a small important reduction in CRP (5 trials; MD: − 0.81 mg/dL; 95% CI: − 1.26 to − 0.37 mg/dL; P MD  = < 0.001; no heterogeneity: I 2  = 0.0%; P Q  = 0.814). There was no interaction by added sugars in soymilk for CRP ( P  = 0.275).

Markers of adiposity

Figure 2 and Additional file 1 : Figs. 14–17 show the effect of substituting soymilk for cow’s milk on markers of adiposity. The substitution had no effect on body weight, BMI, body fat, or waist circumference. There were no interactions by added sugars in soymilk for any adiposity outcome ( P  = 0.664–0.733).

Markers of kidney function

Figure 2 and Additional file 1 : Figs. 18 and 19 show the effect of substituting soymilk for cow’s milk on markers of kidney function. The substitution had no effect on creatinine or eGFR. We could not assess the interaction by added sugars in soymilk for creatinine or eGFR, as there was only one trial available for each outcome which included soymilk without added sugars.

Markers of NAFLD

Figure 2 and Additional file 1 : Figs. 20 and 21 show the effect of substituting soymilk for cow’s milk on markers of NAFLD. The substitution had no effect on ALT or AST. We could not assess heterogeneity or the interaction by added sugars in soymilk for ALT or AST, as there was only one trial available for each outcome which included soymilk without added sugars.

Sensitivity analysis

Additional file 1 : Figs. 22–33 present the influence analyses across all outcomes. The removal of Bricarello et al. [ 53 ] or Steele [ 67 ] each resulted in loss of significant effect for HDL-C. The removal of Onning et al. [ 62 ] or Steele [ 67 ] each resulted in a partial explanation of heterogeneity for triglycerides. The removal of Hasanpour et al. [ 56 ] explained the heterogeneity for fasting insulin. The removal of Keshavarz et al. [ 57 ] or Miraghajani et al. [ 59 ] each resulted in a loss of significant effect for systolic blood pressure and the removal of Rivas et al. [ 63 ] resulted in a partial explanation of the heterogeneity for systolic blood pressure. The removal of Hasanpour et al. [ 56 ], Keshavarz et al. [ 57 ], Miraghajani et al. [ 59 ], or Rivas et al. [ 63 ] each resulted in a loss of significant effect for diastolic blood pressure and the removal of Rivas et al. [ 63 ] resulted in a partial explanation of heterogeneity for diastolic blood pressure. The removal of Mohammad-Shahi et al. [ 58 ] resulted in loss of significant effect for CRP.

Additional file 1 : Table 8 shows the sensitivity analyses for the different correlation coefficients (0.25 and 0.75) used in paired analyses of crossover trials for all outcomes. The different correlation coefficients did not alter the direction, magnitude, or significance of the effect or evidence for heterogeneity, with the following exceptions: loss of significance for the effect of the substitution on HDL-C (8 trials; MD: 0.04 mmol/L; 95% CI: − 0.10 to 0.01 mmol/L; P MD  = 0.107; I 2  = 0.0%; P Q  = 0.670) with the use of 0.25 and (8 trials; MD: 0.05 mmol/L; 95% CI: − 0.10 to 0.01 mmol/L; P MD  = 0.089; I 2  = 0.0%; P Q  = 0.640) with the use of 0.75.

Subgroup analyses

Additional file 1 : Figs. 34–36 present the subgroup analyses and continuous meta-regression analyses for LDL-C. Subgroup analysis was not conducted for any other outcome as there were < 10 trials included. There was no significant effect modification by health status, BMI, age, comparator, baseline LDL-C, study design, follow-up duration, funding source, dose of soy protein, or risk of bias for LDL-C. However, there were tendencies towards a greater reduction in LDL-C by point estimates in groups with certain health statuses (hypercholesterolemic and overweight/obesity), a higher baseline LDL-C, and a higher soy protein dose (> 25 g/day).

Dose–response analyses

Additional file 1 : Figs. 37–42 present linear and non-linear dose–response analyses for LDL-C, HDL-C, non-HDL-C, triglycerides, body weight, and BMI. There was no dose–response seen for the effect of substituting soymilk for cow’s milk, with the exception of a positive linear dose–response for triglycerides ( P linear  = 0.038). We did not downgrade the certainty of evidence as the greater reduction in triglycerides seen at lower doses of soy protein was lost at higher doses. There were no dose–response analyses performed for the remaining outcomes because there were < 6 trials available for each.

Publication bias assessment

Additional file 1 : Fig. 43 presents the contour-enhanced funnel plot for assessment of publication bias for LDL-C. There was no asymmetry at the visual inspection and no evidence (Begg’s test = 0.721, Egger’s test = 0.856) of funnel plot asymmetry for LDL-C. No other publication bias analyses could be performed as there were < 10 trials available for each.

Adverse events and acceptability

Additional file 1 : Table 9 shows the reported adverse events and acceptability of study beverages. Adverse events were reported in nine trials. In one trial by Gardner et al. [ 55 ], one participant experienced a recurrence of a cancer; however, it was considered to be unrelated to the short-term consumption of the study milks. Three trials (Miraghajani et al., Hasanpour et al., and Mohammad-Shahi, et al.) [ 56 , 58 , 59 ] reported one to two withdrawals due to digestive difficulties related to soymilk consumption. Two trials (Sirtori et al. 1999 and 2002) [ 65 , 66 ] reported one or more participants with digestive difficulties related to cow’s milk consumption. Two trials (Nourieh et al. and Keshavarz et al.) [ 57 , 61 ] each reported two participant withdrawals related to digestive problems that were not specific to either study beverage. Of these, four trials indicated that most participants found the soymilk and cow’s milk acceptable and tolerable. One trial, by Onning et al. [ 62 ], incorporated a sensory evaluation of appearance, consistency, flavor, and overall impression, which showed declining scores for both types of milk over the 3-week test period.

GRADE assessment

Additional file 1 : Table 10 presents the GRADE assessment. The certainty of evidence for the effect of substituting soymilk for cow’s milk was high for LDL-C, non-HDL-C, fasting plasma glucose, and waist circumference. The certainty of evidence was moderate for HDL-C, triglycerides, fasting insulin, systolic blood pressure, diastolic blood pressure, CRP, body weight, and BMI owing to a downgrade for imprecision of the pooled effect estimates and was moderate for body fat owing to a downgrade for indirectness. The certainty of evidence was low for HbA1c, 2-h plasma glucose, creatinine, eGFR, ALT, and AST owing to downgrades for indirectness and imprecision.

We conducted a systematic review and meta-analysis of 17 trials that examined the effect of substituting soymilk (median dose of 22 g/day or 6.6 g/250 mL serving of soy protein per day and 17.2 g/day or 6.9 g/250 mL of total [added] sugars in the sweetened soymilk) for cow’s milk (median dose of 24 g/day or 8.3 g/250 mL of milk protein and 24 g/day or 12 g/250 mL of total sugars [lactose]) and its modification by added sugars (sweetened versus unsweetened soymilk) on 19 intermediate cardiometabolic outcomes over a median follow-up period of 4 weeks in adults of varying health status. The substitution of soymilk for cows’ milk led to moderate reductions in non-HDL-C (− 0.26 mmol/L or ~ − 7%) and systolic blood pressure (− 8.00 mmHg) and diastolic blood pressure (− 4.74 mmHg); small important reductions in LDL-C (− 0.19 mmol/L or ~ − 6%) and CRP (− 0.81 mg/L or ~ 22%); and a trivial increase in HDL-C (0.05 mmol/L or ~ 4%), with no adverse effects on other intermediate cardiometabolic outcomes. There was no meaningful interaction by added sugars in soymilk, with sweetened and unsweetened soymilk showing similar effects across outcomes. There was no dose–response relationship seen across the outcomes for which dose–response analyses were performed.

Findings in relation to the literature

Our findings agree with previous evidence syntheses of soy. Regulatory authorities such as the United States Food and Drug Administration (FDA) and Health Canada have conducted comprehensive evaluations of the randomized controlled trials of the effect of soy protein from different sources on total-C and LDL-C, resulting in approved health claims for soy protein (based on an intake of 25 g/day of soy protein irrespective of source) for cholesterol reduction [ 68 ] and coronary heart disease risk reduction [ 69 ]. Updated systematic reviews and meta-analyses of the 46 randomized controlled trials included in the re-evaluation of the FDA health claim [ 70 ] showed reductions in LDL-C of − 3.2% [ 71 ]. This reduction has been stable since the health claim was first approved in 1999 [ 72 ] and is smaller but consistent with our findings specifically for soymilk. No increase in HDL-C, however, was detected. Previous systematic reviews and meta-analyses of randomized controlled trials of soy protein and soy isoflavones have also shown significant but smaller reductions in systolic blood pressure (1.70 mmHg) and diastolic blood pressure (− 1.27 mmHg) [ 73 ] than was found in the current analysis. These reductions in LDL-C and blood pressure are further supported by reductions in clinical events with updated pooled analyses of prospective cohort studies showing that legumes including soy are associated with reduced incidence of total cardiovascular disease and coronary heart disease [ 74 ].

Systematic reviews and meta-analyses that specifically isolated the effect of soymilk (as a single food matrix) in its intended substitution for cow’s milk are lacking. Sohouli and coworkers [ 75 ] conducted a systematic review and meta-analysis of 18 randomized controlled trials in 665 individuals of varying health status that assessed the effect of soymilk in comparison with a mix of comparators on intermediate cardiometabolic outcomes but did not isolate its substitution with cow’s milk. This synthesis showed similar improvements in LDL-C (− 0.24 mmol/L), systolic blood pressure (− 7.38 mmHg), diastolic blood pressure (− 4.36 mmHg), and CRP (− 1.07, mg/L), while also showing reductions in waist circumference and TNF-α [ 75 ]. The substitution of legumes that includes soy for various animal protein sources and more specifically legumes/nuts (the only exposure available) for dairy in syntheses of prospective cohort studies has also shown reductions in incident total cardiovascular disease and all-cause mortality [ 76 ].

Indirect evidence from dietary patterns that contain soy foods including soymilk in substitution for different animal sources of protein including cow’s milk further supports our findings. Systematic reviews and meta-analyses of randomized trials of the Portfolio diet and vegetarian and vegan dietary patterns have shown additive reductions in LDL-C, non-HDL-C, blood pressure, and CRP when soy foods including soymilk are combined with other foods that target these same intermediate risk factors with displacement of different animal sources of protein including cow’s milk [ 77 , 78 ]. These reductions have also been shown to translate to reductions in clinical events with systematic reviews and meta-analyses of prospective cohort studies showing that adherence to these dietary patterns is associated with reductions in incident coronary heart disease, total cardiovascular disease, and all-cause mortality [ 79 , 80 , 81 ].

Potential mechanisms of action

The potential mechanism mediating the effects of soy remains unclear. Specific components within the soy food matrix, including soy protein and phytochemicals like isoflavones [ 82 ], have been implicated. The well-established lipid-lowering effect of soy [ 72 ] may be attributed to the 7S globulin fraction of soy protein, which exerts its primary action by upregulating LDL-C receptors predominantly within the liver, thereby augmenting the clearance of LDL-C from circulation [ 82 ]. The isoflavone, fiber, fatty acids, and anti-nutrient components may also exert some mediation [ 83 ]. The reduction in blood pressure has been most linked to the soy isoflavones [ 83 ]. There is evidence that soy isoflavones may modulate the renin–angiotensin–aldosterone system (RAAS), with the capacity to inhibit the production of angiotensin II and aldosterone, thereby contributing to the regulation of blood pressure [ 73 ]. Another blood pressure lowering mechanism may involve the ability of soy isoflavones to enhance endothelial function by mitigating oxidative stress and inflammation, consequently promoting the release of the relaxing factor nitric oxide (NO) [ 73 ]. This potential mechanism of isoflavones may also explain the reductions seen in inflammation.

Strengths and limitations

Our evidence synthesis had several strengths. First, we completed a comprehensive and reproducible systematic search and selection process of the available literature examining the effect of substituting soymilk for cow’s milk on intermediate cardiometabolic outcomes. Second, we synthesized the totality of available evidence from a large body of randomized controlled trials, which gives the greatest protection against systematic error. Third, we included an extensive and comprehensive list of outcomes to fully capture the impact of soymilk on cardiometabolic health. Fourth, we only included randomized controlled trials that compared soymilk to cow’s milk directly, to increase the specificity of our conclusion. Finally, we included a GRADE assessment to explore the certainty of available evidence.

There were also several limitations. First, we could not conduct the sub-study of the effect of lactose versus added sugars outside of a dairy-like matrix, as no eligible trials could be identified. Although this analysis is important for isolating the effect of added sugars as a mediator of any adverse effects, we did not observe any meaningful interaction by added sugars in soymilk. Second, there was serious imprecision in the pooled estimates across many of the outcomes with the 95% confidence intervals overlapping the MID in each case, with the exception of LDL-C, non-HDL-C, fasting plasma glucose, and waist circumference. The certainty of evidence for HDL-C, triglycerides, HbA1c, fasting plasma glucose, 2-h plasma glucose, fasting insulin, systolic blood pressure, diastolic blood pressure, CRP, body weight, BMI, body fat, creatinine, eGFR, ALT, and AST was downgraded for this reason. Third, there was evidence of indirectness related to insufficient trials for HbA1c, 2-h plasma glucose, creatinine, eGFR, ALT, and AST, which limits generalizability. Each outcome with data from only 1 trial was downgraded for this reason. Another source of indirectness could be the median follow-up duration of 4 weeks (range, 4–16 weeks). This time frame may be sufficient for observing certain effects, but other outcomes may require a longer period to manifest changes. Despite acknowledging this variation in response time among different outcomes, we did not further downgrade for this aspect of indirectness. Instead, we tailored our conclusions to reflect short-to-moderate term effects. Finally, although publication bias was not suspected, we were only able to make this assessment for LDL-C, as there were < 10 trials for all other outcomes.

Considering these strengths and limitations, we assessed the certainty of evidence as high for LDL-C and non-HDL-C; moderate for systolic blood pressure, diastolic blood pressure, CRP, and HDL-C; and moderate-to-low for all outcomes where significant effects were not observed.

Implications

This work has important implications for plant protein foods in the recommended shift to more plant-based diets. Major international dietary guidelines in the US [ 1 ], Canada [ 3 ], and Europe [ 4 , 5 , 6 ] recommend fortified soymilk as the only suitable replacement for cow’s milk. Our findings support this recommendation showing soymilk including sweetened soymilk (up to 7 g added sugars per 250 mL) does not have any adverse effects compared with cow’s milk across 19 intermediate cardiometabolic outcomes with benefits for lipids, blood pressure, and inflammation. This evidence suggests that it may be misleading as it relates to their cardiometabolic effects to classify fortified soymilk as an ultra-processed food to be avoided while classifying cow’s milk as a minimally processed food to be encouraged (based on the WHO-endorsed NOVA classification system [ 10 ]). It also suggests that it may be misleading not to allow fortified soymilk that is sweetened with small amounts of sugars to be classified as “healthy” (based on the FDA’s new proposed definition that only permits this claim on products with added sugars ≤ 2.5 g or 5% daily value (DV) per 250 mL serving [ 16 ]). The proposed FDA criteria would prevent this claim on soymilk products designed to be iso-sweet analogs of cow’s milk (in which 5 g or 10% daily value [DV] of added sugars from sucrose in soymilk is equivalent to the 12 g of lactose in cow’s milk per 250 mL serving, as sucrose is 1.4 sweeter than lactose [ 17 ]). To prevent confusion, policy makers may want to exempt fortified soymilk from classification as an ultra-processed food and allow added sugars up to 10% DV for the definition of “healthy,” as has been proposed by the FDA for sodium and saturated fat in dairy products (including soy-based dairy alternatives) to account for accepted processing and preservation methods [ 16 ]. These policy considerations would balance the need to limit nutrient-poor energy-dense foods with the need to promote nutrient-dense foods like fortified soymilk in the shift to healthy plant-based diets.

In conclusion, the evidence provides a good indication that substituting either sweetened or unsweetened soymilk for cow’s milk in adults with varying health statuses does not have the adverse effects on intermediate cardiometabolic outcomes attributed to added sugars and ultra-processed foods in the short-to-moderate term. There appear even to be advantages with small to moderate reductions in established markers of blood lipids (LDL-C, non-HDL-C) that are in line with approved health claims for cholesterol and coronary heart disease risk reduction, as well as small to moderate reductions in blood pressure and inflammation (CRP). Sources of uncertainty include imprecision and indirectness in several of the estimates. There remains a need for more well-powered randomized controlled trials of the effect of substituting soymilk for cow’s milk on less studied intermediate cardiometabolic outcomes, especially established markers of glycemic control, kidney structure and function, and NAFLD. There is also a need for trials comparing lactose versus added sugars outside of a dairy-like matrix to understand better the role of added sugars at different levels in substitution for lactose across outcomes. In the meantime, our findings support the use of fortified soymilk with up to 7 g added sugars per 250 mL as a suitable replacement for cow’s milk and suggest that its classification as ultra-processed and/or not healthy based on small amounts of added sugars may be misleading and need to be reconsidered to facilitate the recommended transition to plant-based diets.

Availability of data and materials

All data generated or analyzed during this study are included in this published article and its Additional file 1 : information files.

Abbreviations

Grading of Recommendations, Assessment, Development, and Evaluation

Non-high-density lipoprotein cholesterol

Low-density lipoprotein cholesterol

C-reactive protein

High-density lipoprotein cholesterol

World Health Organization

United States

Preferred Reporting Items for Systematic Reviews and Meta-Analysis

High-fructose corn syrup

Body mass index

Apolipoprotein B

Hemoglobin A1c

Plasma glucose area under the curve

Glomerular filtration rate

Estimated glomerular filtration rate

Albumin-creatinine ratio

Non-alcoholic fatty liver disease

Intrahepatocellular lipid

Alanine transaminase

Aspartate aminotransferase

Mean difference

Risk of bias

95% Confidence interval

Generalized least squares trend

Food and Drug Administration

Tumor necrosis factor alpha

Renin-angiotensin-aldosterone system

Nitric oxide

Daily value

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Acknowledgements

Aspects of this work were presented at the following conferences: Canadian Nutrition Society (CNS), Quebec City, Canada, May 4–6, 2023; 40th International Symposium on Diabetes and Nutrition, Pula, Croatia, June 15–18, 2023; and Nutrition 2023—American Society for Nutrition (ASN), Boston, USA, July 22–25, 2023.

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This work was supported by the United Soybean Board (the United States Department of Agriculture Soybean Checkoff Program [funding reference number, 2411–108-0101]) and the Canadian Institutes of Health Research (funding reference number, 129920) through the Canada-wide Human Nutrition Trialists’ Network (NTN). The Diet, Digestive tract, and Disease (3D) Centre, funded through the Canada Foundation for Innovation and the Ministry of Research and Innovation’s Ontario Research Fund, provided the infrastructure for the conduct of this work. ME was funded by a CIHR Canada Graduate Scholarship and Toronto 3D PhD Scholarship award. DG was funded by an Ontario Graduate Scholarship. TAK and AZ were funded by a Toronto 3D Postdoctoral Fellowship Award. LC was funded by a Toronto 3D New Investigator Award. SA-C was funded by a CIHR Canadian Graduate Scholarship. DJAJ was funded by the Government of Canada through the Canada Research Chair Endowment. None of the sponsors had any role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. But one of the co-authors, Mark Messina, who was involved in all aspects of the study except data collection or analysis, is the Director of Nutrition Science and Research at the Soy Nutrition Institute Global, an organization that receives partial funding from the principal funder, the United Soybean Board (USB).

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Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada

M. N. Erlich, D. Ghidanac, S. Blanco Mejia, T. A. Khan, L. Chiavaroli, A. Zurbau, S. Ayoub-Charette, L. A. Leiter, R. P. Bazinet, D. J. A. Jenkins, C. W. C. Kendall & J. L. Sievenpiper

Toronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael’s Hospital, Toronto, ON, Canada

M. N. Erlich, D. Ghidanac, S. Blanco Mejia, T. A. Khan, L. Chiavaroli, A. Zurbau, S. Ayoub-Charette, L. A. Leiter, D. J. A. Jenkins, C. W. C. Kendall & J. L. Sievenpiper

Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, ON, Canada

L. Chiavaroli, L. A. Leiter, D. J. A. Jenkins & J. L. Sievenpiper

Royal College of Surgeons in Ireland, Dublin, Ireland

Soy Nutrition Institute Global, Washington, DC, USA

Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada

L. A. Leiter, D. J. A. Jenkins & J. L. Sievenpiper

Division of Endocrinology and Metabolism, Department of Medicine, St. Michael’s Hospital, Toronto, ON, Canada

College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada

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The authors’ responsibilities were as follows: JLS designed the research (conception, development of overall research plan, and study oversight); ME and DG acquired the data; ME, SBM, TAK, and SAC performed the data analysis; JLS, ME, DG, SBM, AA, TAK, and LC interpreted the data; JLS and ME drafted the manuscript, have primary responsibility for the final content, and take responsibility for the integrity of the data and accuracy of the data analysis; JLS, MNE, DG, SBM, TAK, LC, AZ, SAC, AA, MM, LAL, RPB, CWCK, and DJD contributed to the project conception and critical revision of the manuscript for important intellectual content and read and approved the final version of the manuscript. The corresponding author attests that all listed authors meet the authorship criteria and that no others meeting the criteria have been omitted. All authors read and approved the final manuscript.

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Correspondence to J. L. Sievenpiper .

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Competing interests.

TAK reports receiving grants from Institute for the Advancement of Food and Nutrition Sciences (IAFNS, formerly ILSI North America) and National Honey Board (USDA Checkoff program). He has received honorariums from Advancement of Food and Nutrition Sciences (IAFNS), the International Food Information Council (IFIC), the Calorie Control Council (CCC), the International Sweeteners Association (ISA), and AmCham Dubai. He has received funding from the Toronto 3D Knowledge Synthesis and Clinical Trials foundation. LC has received research support from the Canadian Institutes of health Research (CIHR), Protein Industries Canada (a Government of Canada Global Innovation Clusters), The United Soybean Board (USDA soy “Checkoff” program), and the Alberta Pulse Growers Association. AZ is a part-time research associate at INQUIS Clinical Research, Ltd., a contract research organization. She has received consulting fees from Glycemic Index Foundation Inc. SA-C has received an honorarium from the International Food Information Council (IFIC) for a talk on artificial sweeteners, the gut microbiome, and the risk for diabetes. MM was employed by the Soy Nutrition Institute Global, an organization that receives funding from the United Soybean Board (USB) and from members involved in the soy industry. RPB has received industrial grants, including those matched by the Canadian government, and/or travel support or consulting fees largely related to work on brain fatty acid metabolism or nutrition from Arctic Nutrition, Bunge Ltd., Dairy Farmers of Canada, DSM, Fonterra Inc, Mead Johnson, Natures Crops International, Nestec Inc. Pharmavite, Sancero Inc., and Spore Wellness Inc. Moreover, Dr. Bazinet is on the executive of the International Society for the Study of Fatty Acids and Lipids and held a meeting on behalf of Fatty Acids and Cell Signaling, both of which rely on corporate sponsorship. Dr. Bazinet has given expert testimony in relation to supplements and the brain. DJAJ has received research grants from Saskatchewan & Alberta Pulse Growers Associations, the Agricultural Bioproducts Innovation Program through the Pulse Research Network, the Advanced Foods and Material Network, Loblaw Companies Ltd., Unilever Canada and Netherlands, Barilla, the Almond Board of California, Agriculture and Agri-food Canada, Pulse Canada, Kellogg’s Company, Canada, Quaker Oats, Canada, Procter & Gamble Technical Centre Ltd., Bayer Consumer Care, Springfield, NJ, Pepsi/Quaker, International Nut & Dried Fruit Council (INC), Soy Foods Association of North America, the Coca-Cola Company (investigator initiated, unrestricted grant), Solae, Haine Celestial, the Sanitarium Company, Orafti, the International Tree Nut Council Nutrition Research and Education Foundation, the Peanut Institute, Soy Nutrition Institute (SNI), the Canola and Flax Councils of Canada, the Calorie Control Council, the Canadian Institutes of Health Research (CIHR), the Canada Foundation for Innovation (CFI), and the Ontario Research Fund (ORF). He has received in-kind supplies for trials as a research support from the Almond board of California, Walnut Council of California, the Peanut Institute, Barilla, Unilever, Unico, Primo, Loblaw Companies, Quaker (Pepsico), Pristine Gourmet, Bunge Limited, Kellogg Canada, and WhiteWave Foods. He has been on the speaker’s panel, served on the scientific advisory board and/or received travel support and/or honoraria from Lawson Centre Nutrition Digital Series, Nutritional Fundamentals for Health (NFH)-Nutramedica, Saint Barnabas Medical Center, The University of Chicago, 2020 China Glycemic Index (GI) International Conference, Atlantic Pain Conference, Academy of Life Long Learning, the Almond Board of California, Canadian Agriculture Policy Institute, Loblaw Companies Ltd, the Griffin Hospital (for the development of the NuVal scoring system), the Coca-Cola Company, Epicure, Danone, Diet Quality Photo Navigation (DQPN), Better Therapeutics (FareWell), Verywell, True Health Initiative (THI), Heali AI Corp, Institute of Food Technologists (IFT), Soy Nutrition Institute (SNI), Herbalife Nutrition Institute (HNI), Saskatchewan & Alberta Pulse Growers Associations, Sanitarium Company, Orafti, the International Tree Nut Council Nutrition Research and Education Foundation, the Peanut Institute, Herbalife International, Pacific Health Laboratories, Barilla, Metagenics, Bayer Consumer Care, Unilever Canada and Netherlands, Solae, Kellogg, Quaker Oats, Procter & Gamble, Abbott Laboratories, Dean Foods, the California Strawberry Commission, Haine Celestial, PepsiCo, the Alpro Foundation, Pioneer Hi-Bred International, DuPont Nutrition and Health, Spherix Consulting and WhiteWave Foods, the Advanced Foods and Material Network, the Canola and Flax Councils of Canada, Agri-Culture and Agri-Food Canada, the Canadian Agri-Food Policy Institute, Pulse Canada, the Soy Foods Association of North America, the Nutrition Foundation of Italy (NFI), Nutra-Source Diagnostics, the McDougall Program, the Toronto Knowledge Translation Group (St. Michael’s Hospital), the Canadian College of Naturopathic Medicine, The Hospital for Sick Children, the Canadian Nutrition Society (CNS), the American Society of Nutrition (ASN), Arizona State University, Paolo Sorbini Foundation, and the Institute of Nutrition, Metabolism and Diabetes. He received an honorarium from the United States Department of Agriculture to present the 2013 W.O. Atwater Memorial Lecture. He received the 2013 Award for Excellence in Research from the International Nut and Dried Fruit Council. He received funding and travel support from the Canadian Society of Endocrinology and Metabolism to produce mini cases for the Canadian Diabetes Association (CDA). He is a member of the International Carbohydrate Quality Consortium (ICQC). His wife, Alexandra L Jenkins, is a director and partner of INQUIS Clinical Research for the Food Industry, his 2 daughters, Wendy Jenkins and Amy Jenkins, have published a vegetarian book that promotes the use of the foods described here, The Portfolio Diet for Cardiovascular Risk Reduction (Academic Press/Elsevier 2020 ISBN:978–0-12–810510-8), and his sister, Caroline Brydson, received funding through a grant from the St. Michael’s Hospital Foundation to develop a cookbook for one of his studies. He is also a vegan. CWCK has received grants or research support from the Advanced Food Materials Network, Agriculture and Agri-Foods Canada (AAFC), Almond Board of California, Barilla, Canadian Institutes of Health Research (CIHR), Canola Council of Canada, International Nut and Dried Fruit Council, International Tree Nut Council Research and Education Foundation, Loblaw Brands Ltd, the Peanut Institute, Pulse Canada, and Unilever. He has received in-kind research support from the Almond Board of California, Barilla, California Walnut Commission, Kellogg Canada, Loblaw Companies, Nutrartis, Quaker (PepsiCo), the Peanut Institute, Primo, Unico, Unilever, and WhiteWave Foods/Danone. He has received travel support and/or honoraria from the Barilla, California Walnut Commission, Canola Council of Canada, General Mills, International Nut and Dried Fruit Council, International Pasta Organization, Lantmannen, Loblaw Brands Ltd, Nutrition Foundation of Italy, Oldways Preservation Trust, Paramount Farms, the Peanut Institute, Pulse Canada, Sun-Maid, Tate & Lyle, Unilever, and White Wave Foods/Danone. He has served on the scientific advisory board for the International Tree Nut Council, International Pasta Organization, McCormick Science Institute, and Oldways Preservation Trust. He is a founding member of the International Carbohydrate Quality Consortium (ICQC), Executive Board Member of the Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD), is on the Clinical Practice Guidelines Expert Committee for Nutrition Therapy of the EASD, and is a Director of the Toronto 3D Knowledge Synthesis and Clinical Trials foundation. JLS has received research support from the Canadian Foundation for Innovation, Ontario Research Fund, Province of Ontario Ministry of Research and Innovation and Science, Canadian Institutes of health Research (CIHR), Diabetes Canada, American Society for Nutrition (ASN), National Honey Board (U.S. Department of Agriculture [USDA] honey “Checkoff” program), Institute for the Advancement of Food and Nutrition Sciences (IAFNS), Pulse Canada, Quaker Oats Center of Excellence, INC International Nut and Dried Fruit Council Foundation, The United Soybean Board (USDA soy “Checkoff” program), Protein Industries Canada (a Government of Canada Global Innovation Cluster), Almond Board of California, European Fruit Juice Association, The Tate and Lyle Nutritional Research Fund at the University of Toronto, The Glycemic Control and Cardiovascular Disease in Type 2 Diabetes Fund at the University of Toronto (a fund established by the Alberta Pulse Growers), The Plant Protein Fund at the University of Toronto (a fund which has received contributions from IFF among other donors), The Plant Milk Fund at the University of Toronto (a fund established by the Karuna Foundation through Vegan Grants), and The Nutrition Trialists Network Fund at the University of Toronto (a fund established by donations from the Calorie Control Council and Physicians Committee for Responsible Medicine). He has received food donations to support randomized controlled trials from the Almond Board of California, California Walnut Commission, Danone, Nutrartis, Soylent, and Dairy Farmers of Canada. He has received travel support, speaker fees and/or honoraria from Danone, FoodMinds LLC, Nestlé, Abbott, General Mills, Nutrition Communications, International Food Information Council (IFIC), Arab Beverages, International Sweeteners Association, Association Calorie Control Council, and Phynova. He has or has had ad hoc consulting arrangements with Perkins Coie LLP, Tate & Lyle, Ingredion, and Brightseed. He is on the Clinical Practice Guidelines Expert Committees of Diabetes Canada, European Association for the study of Diabetes (EASD), Canadian Cardiovascular Society (CCS), and Obesity Canada/Canadian Association of Bariatric Physicians and Surgeons. He serves as an unpaid member of the Board of Trustees of IAFNS. He is a Director at Large of the Canadian Nutrition Society (CNS), founding member of the International Carbohydrate Quality Consortium (ICQC), Executive Board Member of the Diabetes and Nutrition Study Group (DNSG) of the EASD, and Director of the Toronto 3D Knowledge Synthesis and Clinical Trials foundation. His spouse is an employee of AB InBev. All other authors declare that they have no competing interests.

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12916_2024_3524_moesm1_esm.docx.

Additional file 1: This file contains Additional file 1 material, including the PRISMA checklist, further details on the search process, and additional results.

Flow of literature on the effect of substituting soymilk for cow’s milk on intermediate cardiometabolic outcomes. Exclusion criteria: duplicate, abstract only (conference abstract), non-human (animal study), in vitro, review/position paper/commentary/letter, observational (observational study), no soymilk (intervention was not soymilk), children (participants < 18 years of age), no suitable comparator (comparator was not cow’s milk), isolated soy protein (an ISP powder was given to participants), acute (follow-up of < 3 weeks), combined intervention (effects of intervention and comparator could not be isolated), wrong endpoint (no data for outcomes of interest), alternative publication (repeated data from original publication)

A summary plot for the effect of substituting soymilk for cow’s milk on intermediate cardiometabolic outcomes. Analyses were conducted using generic, inverse variance random-effects models (at least 5 trials available), or fixed-effects models (fewer than 5 trials available). Between-study heterogeneity was assessed by the Cochrane Q statistic, where P Q  < 0.100 was considered statistically significant, and quantified by the I 2 statistic, where I 2  ≥ 50% was considered evidence of substantial heterogeneity. The GRADE of randomized controlled trials are rated as “high” certainty of evidence and can be downgraded by 5 domains and upgraded by 1 domain. The white squares represent no downgrades, the filled black squares indicate a single downgrade or upgrades for each outcome, and the black square with a white “2” indicates a double downgrade for each outcome. Because all included trials were randomized or nonrandomized controlled trials, the certainty of the evidence was graded as high for all outcomes by default and then downgraded or upgraded based on prespecified criteria. Criteria for downgrades included risk of bias (downgraded if most trials were considered to be at high ROB); inconsistency (downgraded if there was substantial unexplained heterogeneity: I 2  ≥ 50%; P Q  < 0.10); indirectness (downgraded if there were factors absent or present relating to the participants, interventions, or outcomes that limited the generalizability of the results); imprecision (downgraded if the 95% CI crossed the minimally important difference (MID) for harm or benefit); and publication bias (downgraded if there was evidence of publication bias based on the funnel plot asymmetry and/or significant Egger or Begg test ( P  < 0.10)), with confirmation by adjustment using the trim-and-fill analysis of Duval and Tweedie. The criteria for upgrades included a significant dose–response gradient. For the interpretation of the magnitude, we used the MIDs to assess the importance of magnitude of our point estimate using the effect size categories according to the new GRADE guidance. Then, we used the MIDs to assess the importance of the magnitude of our point estimates using the effect size categories according to the GRADE guidance as follows: a large effect (≥ 5 × MID); moderate effect (≥ 2 × MID); small important effect (≥ 1 × MID); and trivial/unimportant effect (< 1 MID). *HDL-C values reversed to show benefit. **LDL-C was not downgraded for imprecision, as the degree to which the upper 95% CI crosses the MID is not clinically meaningful. Additionally, the moderate change in non-HDL-C, with high certainty of evidence, substantiates the high certainty of the LDL-C results.

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Erlich, M.N., Ghidanac, D., Blanco Mejia, S. et al. A systematic review and meta-analysis of randomized trials of substituting soymilk for cow’s milk and intermediate cardiometabolic outcomes: understanding the impact of dairy alternatives in the transition to plant-based diets on cardiometabolic health. BMC Med 22 , 336 (2024). https://doi.org/10.1186/s12916-024-03524-7

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Received : 20 December 2023

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DOI : https://doi.org/10.1186/s12916-024-03524-7

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Animal/Plant Research Project (grade 4)

• Google Slides™

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Description

This resource has been developed for the newly updated Ontario Science curriculum. It involves gathering information about a plant or animal of choice. It aligns with the Life Systems - Habitats and Communities grade 4 curriculum and it follows the scientific research process. It has been created using a google slideshow that can be edited for your students needs.

Questions & Answers

Jenni's elementary teacher resources.

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