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Is Soy Protein Good or Bad for You?

Soybeans have become a very popular option today since it can be made into a variety of products such as soy milk, tempeh, tofu, and other types of dairy and meat alternatives. Soybean can also be turned into soy protein powder. For vegans, vegetarians, and people who are allergic to or avoid having dairy products, these soy products are serving as the primary source of protein. Nevertheless, there are many controversies associated with soy. While many people believe soy to be a nutritional powerhouse, others believe it to be harmful to health. Let’s take a look at whether soy protein is good or bad for you based on the nutritional facts of soy protein, its health benefits and drawbacks.

Is Soy Protein Good or Bad for You?

Is Soy Protein Good or Bad for You?

Nutritional Facts of Soy Protein

Soy protein is typically found in the form of soy protein isolate powder. This is made from defatted soybean flakes that have been cleaned in water or alcohol for removing the dietary fiber and sugars. Following the washing, they are then dehydrated and then turned into a powder. This soy protein isolate powder contains minimal fat and no cholesterol.

Soy protein powder is used for making infant soy formula as well as a variety of dairy and meat alternatives.

The nutritional content of one cup (28 grams or one ounce) of soy protein isolate powder.(1)

  • Total Calories: 95
  • Protein: 23 grams
  • Fat: 1 gram
  • Carbohydrates: 2 grams
  • Iron: 25% of Daily Value (DV)
  • Fiber: 1.6 grams
  • Phosphorus: 22% of DV
  • Manganese: 21% of DV
  • Copper: 22% of DV

Soy protein isolate powder is a concentrated form of protein. It is also known to contain phytates, which decreases mineral absorption.

Health Benefits of Soy Protein

Adding soy protein to your diet can provide many health benefits. For example, soy-based foods are known to have a positive effect on your heart health. Soy protein is known to also reduce the level of total cholesterol and bad LDL cholesterol in the body, along with triglyceride levels as well.

There also have been some observational studies that have associated a high soy intake to a reduced risk of breast cancer.(2) On the other hand, a study has also linked soy intake to an increase in cell production in the breasts of premenopausal women, thus increasing the risk of breast cancer.(3)

So even though studies have shown mixed results on whether soy protein powder can help reduce the risk of certain cancers, many studies have effectively found that soy protein can be beneficial in many aspects of your health.

What are the Drawbacks of Taking Soy Protein?

While there are many proponents of soy protein, there are also others who have concerns about soy. As mentioned earlier, soy protein contains a compound known as phytates, which is known to be an antinutrient. Phytates decrease the availability of zinc and iron in soy protein.(4)

However, phytates do not necessarily harm your health, unless your diet is drastically imbalanced, and you solely rely on soy protein as your primary source of zinc and iron. Additionally, there is also some concern that high soy intake might affect thyroid function in the body. This is because of the presence of isoflavones in soy that function as goitrogens. Goitrogens are known to interfere with thyroid function as well as the production of hormones by the thyroid gland. Nevertheless, studies have found that soy has almost no to very mild effect on thyroid function in humans.(5)

Some people also avoid soy protein due to the phytoestrogen content in soy. They fear that phytoestrogens can cause an imbalance in the natural hormone levels of the body.

While soy is a major source of phytoestrogens, which are chemical compounds that are found naturally in plants and have similar properties as estrogen, but in the manufacturing process of soy protein powder, a substantial portion of the phytoestrogen content is removed in the washing process with alcohol and water.

So overall, there is relatively weak evidence to support any of the potential drawbacks associated with eating soy protein. This is why it is safe to assume that people can continue to eat soy with no issues.


Soy protein is a powerhouse of protein, and it has many nutritional benefits for your body. Not only does soy help in muscle building, but it may also lower the risk of cancer, help you lose weight, boost your heart health, and lower the levels of bad cholesterol and triglycerides. Soy is considered to be safe for most people, and due to a lack of any substantial evidence regarding the drawbacks of soy protein, you can continue consuming soy without any worries.


  1. Butteiger, D.N., Cope, M., Liu, P., Mukherjea, R., Volpi, E., Rasmussen, B.B. and Krul, E.S., 2013. A soy, whey and caseinate blend extends postprandial skeletal muscle protein synthesis in rats. Clinical nutrition, 32(4), pp.585-591.
  2. Nishio, K., Niwa, Y., Toyoshima, H., Tamakoshi, K., Kondo, T., Yatsuya, H., Yamamoto, A., Suzuki, S., Tokudome, S., Lin, Y. and Wakai, K., 2007. Consumption of soy foods and the risk of breast cancer: findings from the Japan Collaborative Cohort (JACC) Study. Cancer Causes & Control, 18(8), pp.801-808.
  3. McMichael-Phillips, D.F., Harding, C., Morton, M., Roberts, S.A., Howell, A., Potten, C.S. and Bundred, N.J., 1998. Effects of soy-protein supplementation on epithelial proliferation in the histologically normal human breast. The American journal of clinical nutrition, 68(6), pp.1431S-1435S.
  4. Hurrell, R.F., Juillerat, M.A., Reddy, M.B., Lynch, S.R., Dassenko, S.A. and Cook, J.D., 1992. Soy protein, phytate, and iron absorption in humans. The American journal of clinical nutrition, 56(3), pp.573-578.
  5. Messina, M. and Redmond, G., 2006. Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature. Thyroid, 16(3), pp.249-258.

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:February 5, 2020

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