Soy Protein: Good Or Bad? - Nutrition - Healthline

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Evidence BasedWhat Is Soy Protein? All You Need to Know

Medically reviewed by Alissa Palladino, MS, RDN, LD, CPT — Written by Lauren Panoff, MPH, RD and Amy Goodson, MS, RD, CSSD, LD — Updated on November 26, 2025

Types of soy
Nutrients
Amino acids
Benefits
Drawbacks
Weight loss
Recipe ideas
FAQ
Takeaway

Soy protein is the primary protein found in soy products, including tofu, tempeh, soy milk, soy beans, and other soy-based alternatives to dairy and meat.

It can also be found in the form of soy protein powder, which you can use to supplement your workout routine or add more protein to your diet.

For people following a plant-based diet or those who avoid dairy, soy foods serve as a major source of protein, as well as essential vitamins and minerals.

Soy is, in fact, a nutrient powerhouse despite misconceptions and unfounded fears.

Just one thing

Try this today: Soy is an inexpensive, versatile source of protein, whether or not you follow a plant-based diet. It’s easy to make a tofu scramble by crumbling extra-firm tofu into a skillet and cooking with olive oil, chopped greens, veggies, and seasonings.

Types of soy foods

Soy comes in a wide variety of forms, each with varying nutritional value and health benefits.

Minimally processed soy

On one end of the spectrum are whole or minimally processed soy foods, such as tofu, tempeh, and whole soybeans, also known as edamame.

Soybeans or edamame: Edamame are young soybeans eaten fresh from their pods, whilst soy beans are the older version that make products such as tofu or soy milk.
Tempeh: This dense, nutty cake or patty involves partially cooking whole soybeans, then fermenting them with the mold Rhizopus oligosporus. It has a firmer texture than tofu.
Natto: This traditional Japanese breakfast dish consists of fermented soybeans inoculated with Bacillus subtilis var. natto. It’s commonly served over rice.
Miso: You can use this flavorful paste in a variety of soups and other recipes. It’s made from fermented soybeans and barley or rice malt, and production involves the use of Koji enzymes and beneficial microbes.

More processed soy

Soy milk is slightly more processed. To make soy milk, you cook soybeans in water, pulverize them, and press to remove the solids and fiber. Manufacturers may add other ingredients and nutrients.

Tofu is a popular plant-based protein that stems from condensed soy milk in a process that resembles cheesemaking. It’s shaped into spongy, solid white blocks of soy curds, available in silken, firm, and extra-firm textures.

On the most highly processed end of the spectrum, you’ll find soy protein powder or soy protein isolate. They’re an ingredient in certain packaged foods, such as protein bars.

Soy protein isolate powder comes from defatted soybean flakes washed in either alcohol or water to remove the sugars and fiber. They’re then dehydrated and powdered. Soy protein concentrate typically contains approximately 70% protein, while soy protein isolate typically contains around 90%.

»Learn more:Is Eating Soy Healthy or Unhealthy?

Nutrition facts of soy foods

The nutritional composition of soy foods varies depending on the type you’re consuming.

Overall, soy is a good source of protein and fiber, as well as vitamins and minerals like calcium, iron, magnesium, and zinc. It contains some unsaturated fat and is cholesterol-free.

This chart displays the nutritional information for one serving of tofu and soy protein isolate powder.

Firm calcium-set tofu,1/2 cup (126 grams)	Soy protein isolate powder, 1 ounce (28 grams)
Calories	181	95
Protein	22 grams	25 grams
Total fat	11 grams	1 gram
Carbs	3.5 grams	0 grams
Fiber	3 grams	0 grams
Calcium	66% of the Daily Value (DV)	4% of the DV
Iron	18% of the DV	23% of the DV
Magnesium	17% of the DV	3% of the DV
Phosphorus	19% of the DV	18% of the DV
Potassium	4% of the DV	less than 1% of the DV
Zinc	11% of the DV	10% of the DV

The quantities of these nutrients vary greatly based on the type of soy food.

Soy protein isolate packs a significant amount of protein per serving, as it is a processed and concentrated source of this nutrient.

Does soy food offer amino acids?

Most plant foods, with a few exceptions, including soy, are, in fact, inferior to animal proteins in that they do not contain all the essential amino acids necessary for building and repairing human tissues.

That said, you can still get all the amino acids you need by eating a variety of plant protein foods, but there is a difference in the protein quality of an individual plant food versus eating a balanced, varied diet with a bunch of different plant foods

All plants contain all nine essential amino acids, but some only offer very limited amounts. For instance, lysine only occurs in small amounts in most grains and cereals.

This simply means that you should incorporate other sources of lysine into your diet, such as soy, so that your body can synthesize all the protein it needs. To maintain your overall health, simply enjoy a diverse diet.

Soy foods not only contain all nine essential amino acids but also provide ample amounts of each, making them similar to animal proteins in this regard.

Health benefits of soy foods

Soy may support heart health, reduce cancer risk, and help regulate blood sugar levels. These benefits are largely attributed to soy’s health-promoting compounds, including phytosterols, lecithin, phytic acid, and isoflavones, as well as its nutritional profile.

May protect heart health

Soy foods appear to have positive effects on heart health. In one 2022 study, soy products were found to reduce the risk of cardiovascular disease in patients with type 2 diabetes by:

reducing LDL or “bad” cholesterol
reducing triglycerides, which are fats found in the blood that can increase the risk of hardening of the arteries
reducing C-reactive protein, a marker of inflammation in the body

May offer anticancer benefits

Numerous observational studies suggest that a high-soy diet may protect against cancer risk, outcomes, and even recurrence. Still, it’s essential to note that these benefits are primarily associated with whole and minimally processed soy foods, rather than supplemental soy protein isolate.

Another review found a statistically significant link between soy food intake and a lower risk of prostate cancer.

May support blood sugar regulation

Eating soy foods links to better blood sugar management, which is especially important for people who have — or are at risk of — diabetes.

Some research indicates that fermented soy foods may be particularly effective in helping minimize the effects of diabetes.

Fermented soy offers a range of benefits, including antioxidant and anti-inflammatory effects, as well as improved gut health.

Potential downsides of soy foods

Some people have concerns about soy, particularly regarding compounds called antinutrients and phytoestrogens. Others worry that soy foods are genetically modified.

Antinutrients

Soy contains phytates, which are plant compounds categorized as antinutrients, alongside lectins, oxalates, and tannins. Antinutrients can reduce the availability of minerals such as calcium, iron, and zinc.

However, phytates aren’t harmful unless your diet is severely imbalanced and you rely on soy protein as your main source of iron and zinc.

»Learn more:How to Reduce Antinutrients in Foods

Genetic modification

The majority of soy beans grown worldwide are genetically modified (GMO), meaning they have been genetically altered to be resistant to certain herbicides.

Some people have concerns about the unknown long-term health effects of GMO foods. Most current research on the health effects of GMOs is conflicting, and long-term studies are necessary. Some research suggests that greater acceptance of GMO foods is necessary for people to overcome unfounded fears and adequately feed a growing population.

Regardless, non-GMO soy products are available at most grocery stores. If you want to avoid GMO soy, you can opt for certified organic products, as this ensures they are free from genetically modified organisms.

May aid weight loss

Including soy protein in your diet may support weight loss. Studies indicate that high protein diets are an effective tool for weight loss.

One 2024 study found that having soy protein helped maintain a lower calorie intake. People did not lose weight during the trial; however, the lower calorie intake on the soy protein diet suggests that there could be a longer-term effect.

»MORE:Science-Backed Tips to Lose Weight Fast and Sustainably

How to enjoy soy protein

Soy is incredibly versatile and easy to add to your diet. Some easy ways to prepare it include:

Drain a block of extra-firm tofu, then pat it dry. Cut into cubes, season, and roast in the oven for a quick snack, salad topper, or stir-fry ingredient.
Crumble a block of extra-firm tofu and cook it on the stove with veggies for a vegan scrambled egg substitute.
Slice a block of extra-firm tube and grill or fry it to use in sandwiches.
Add a slice of silken tofu to smoothies for an extra boost of protein.
Crumble a block of tempeh for crockpot chilis, stews, or plant-based sloppy joes.
Use prepackaged tempeh “bacon” to make a plant-based BLT.
Cook edamame and season with salt for a side dish.
Add miso to soups or homemade salad dressings.
Replace dairy milk with fortified soy milk in baked goods, soups, smoothies, sauces, and breakfast cereals.
Add a scoop of soy protein powder to your pre- or post-workout smoothies.

Frequently asked questions

What is special about soy protein?

Benefits of soy protein include:

protecting heart health
helping manage blood sugar
aiding in weight loss
offering anticancer benefits

Why do people say to avoid soy?

Some people may believe that soy causes a rise in estrogen, contributing to conditions such as breast cancer.

Is soy a highly inflammatory food?

No, soy actually has antinflammatory effects on the body.

Takeaway

Soy is a good source of protein, fiber, and a variety of essential vitamins and minerals. It also contains health-promoting compounds, such as isoflavones.

Though you may have heard concerns about soy’s GMO status or phytoestrogen content, most scientific evidence suggests that there’s no need to avoid soy products.

In fact, eating soy protein — especially whole and minimally processed foods like edamame, tofu, and tempeh — may offer numerous benefits for heart health, blood sugar management, weight loss, and even cancer risk and recurrence.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Goodman RE, et al. (2023). Twenty-eight years of GM Food and feed without harm: why not accept them?https://www.tandfonline.com/doi/full/10.1080/21645698.2024.2305944
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Hashimoto Y, et al. (2023). Fermented soybean foods and diabetes.https://pmc.ncbi.nlm.nih.gov/articles/PMC10688128/
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Hui X, et al. (2024). Understanding the societal dilemma of genetically modified food consumption: a stimulus-organism-response investigation.https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2024.1364052/full
Lim JJ, et al. (2022). Does a higher protein diet promote satiety and weight loss independent of carbohydrate content? An 8-week low-energy diet (LED) intervention.https://www.mdpi.com/2072-6643/14/3/538
López-Moreno M, et al. (2022). Antinutrients: Lectins, goitrogens, phytates and oxalates, friends or foe?https://www.sciencedirect.com/science/article/pii/S1756464622000081
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Rajaie SH, et al. (2025). The impact of soy products and isoflavones on male reproductive hormones: A systematic review and dose–response meta-analysis of randomized controlled trials.https://iadns.onlinelibrary.wiley.com/doi/10.1002/fft2.70090
Saeed F, et al. (2022). Miso: A traditional nutritious & health‐endorsing fermented product.https://pmc.ncbi.nlm.nih.gov/articles/PMC9731531/
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Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

Our team of licensed nutritionists and dietitians strive to be objective, unbiased, honest and to present both sides of the argument.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

Medically reviewed by Alissa Palladino, MS, RDN, LD, CPT — Written by Lauren Panoff, MPH, RD and Amy Goodson, MS, RD, CSSD, LD — Updated on November 26, 2025

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Nutrition

Nutrition

Just one thing

Types of soy foods

Minimally processed soy

More processed soy

Nutrition facts of soy foods

Does soy food offer amino acids?

Health benefits of soy foods

May protect heart health

May offer anticancer benefits

May support blood sugar regulation

Potential downsides of soy foods

Antinutrients

Genetic modification

May aid weight loss

How to enjoy soy protein

Frequently asked questions

What is special about soy protein?

Why do people say to avoid soy?

Is soy a highly inflammatory food?

Takeaway

How we reviewed this article:

Evidence Based

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