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.
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%.
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 | ||
| 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.
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.
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.
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.
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.
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.
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.
Benefits of soy protein include:
- protecting heart health
- helping manage blood sugar
- aiding in weight loss
- offering anticancer benefits
Some people may believe that soy causes a rise in estrogen, contributing to conditions such as breast cancer.
No, soy actually has antinflammatory effects on the body.
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.