Soy Beans: What the Experts Say

Soy is one of the most versatile and pervasive foods in the American diet.1 Many people consume this ingredient every day without knowing it. Baked goods, sauces, and meat and meat substitutes are just a handful of these products.2 

Soybeans were first grown in Asia about 5,500 years ago but experienced a boon in production in the 1950s when they spread across the globe.1,3 Now, soy is a globally traded commodity, with about 80 percent of soybeans grown in the United States, Brazil, and Argentina.3,4 So, how did the humble soybean become the “king of beans” in the last 70 years?4 


Soy’s ubiquity can partially be attributed to its seed’s viability. This crop can be grown easily and cheaply in variable conditions, from tropical to temperate climates.3,4 Soybeans are also resilient, able to withstand temperatures as low as 45ºF and as high as 95ºF.5 Given this, their growth is expected to be largely unaffected by climate change, and there is research underway to develop “drought-smart” soybeans that could boost this resilience even further.6-9 On top of their viability and resilience, soybeans are quick to grow. In ideal conditions, the seeds can sprout just 4 to 7 days after they are planted!10

Soybeans are known for having an incredibly high density of proteins and fats, and the ideal method for separating these components depends on what which component is being extracted.1,10 Once the crop is harvested, soybeans are taken to a processing plant where they are cleaned, dried, cleaned again, cracked, and dehulled (i.e., the outer shell or coating of the seed is removed).11 These cracked beans are then heated and rolled into flakes. At this point, the oil, protein, and  meal are extracted from the flakes.

Oil. This byproduct is created by extracting the oil from the flakes. To do this, the flakes are put in a solvent wash, where the crude oil is separated from the solvent mixture.11 This liquid is then refined, bleached, and deodorized, resulting in the clear and odorless soybean oil that we use for edible and non-edible uses.

Protein. In order to isolate soybean proteins, the flakes—or even the whole bean—are steeped in water and ground into a whitish, protein-rich liquid.1

Meal. After removing oil from the flakes, soybean meal is created from the remaining defatted flakes, which are then toasted, dried, and ground for use as a protein source. This meal is used in livestock and pet feed, human food applications, and industrial uses.11


The versatile and varied uses of soybean oil, protein, and meal are what makes soy so widely consumed. In fact, soybean oil is the most commonly used edible oil in the United States (US), according to the US Department of Agriculture (USDA).12 This is due to several factors. Its mild taste makes it suitable to enhance and support the natural flavors of prepared foods.13 Perhaps most notably, soybean oil is an excellent binding agent,1 meaning it more effectively blends and binds ingredients and other substances that naturally separate from each other, which makes it the first choice of the general food industry.1,14 This ingredient is also widely used in vegetable oils, salad dressings, mayonnaise, gravy, and a variety of sauces, such as steak, Worcestershire, and, of course, soy sauce.2

The proteins and fats from soy can be used to make a variety of foods. These foods generally fall into two categories: fermented and unfermented. Unfermented foods include tofu, soy milk, edamame, soy nuts, and soy sprouts, while fermented soy products include miso, tempeh, natto, and soy sauce.15 You may notice that many of these foods are common meat substitutes. That’s because soy is one of a few plant-based foods that are a complete protein source (most complete protein sources are animal-based).16,17 While the fats found in meat are often of the “bad” (saturated) variety, soy’s fat content is largely of the “good” (poly- and mono-unsaturated) variety, which can decrease cholesterol and reduce the risk of heart disease.1

Soybean meal is another surprising source of soy in our diets. Because it is a cost-effective product that is widely available, it is often used as animal feed for livestock. This means that some of those animals’ byproducts, such as meat, eggs, and milk, are in an indirect source of soy in trace amounts in the human diet.


The general consensus among experts is that soy is a healthy food source, but research surrounding its nutritional benefits have been mixed.1,3,16,19-21 This is especially true regarding its effects on heart disease, menopause, diabetes, certain cancers, and brain function. Many studies on soy have had inconclusive results, but researchers concede this may be due to the wide variation in how soy is studied and the intricacy of its effects on the body.19 For example, study results can be affected by the type of study (e.g., humans vs. animals, controlled vs. uncontrolled), the outcomes being measured, and the type of soy being studied (e.g., whole soy vs. processed soy, fermented vs. unfermented, etc.). Though there are still uncertainties about soy’s health effects, results of recent population studies suggest that minimally processed soy has either a beneficial or neutral effect on various health conditions.1,3,19


WE KNOW … that soy is a nutrient-dense source of protein that can safely be consumed several times a week.1,3,19-21 It is also likely to provide some health benefits, especially when eaten as an alternative to red or processed meat.

WE DO NOT KNOW … whether soy can prevent heart disease.3,21 In 2000, the US Food and Drug Administration (FDA) backed claims that soy protects against heart disease but revoked that claim in 2017.23 Similarly, the American Heart Association’s 2006 diet and lifestyle recommendations and science advisory found minimal evidence that soy’s isoflavones have any cardiovascular benefits.24

WE KNOW … that soy may decrease breast cancer risk.3 Observational studies indicate that among Asian women, higher dietary intakes of soy during childhood and adolescence were associated with a lower risk of breast cancer later in life. However, the amount of soy in Western diets may be too low for this association to be observed.25,26

WE DO NOT KNOW … whether genetically modified (GMO) soy contains fewer nutrients and more herbicide residues than conventional or organic soy.1,27,28 More research is needed on the longitudinal effects of GMOs.

WE KNOW … that, generally speaking, the less processed soy is, the more vitamins, minerals, and beneficial compounds it may contain.29-31 Several peer-reviewed and published reviews have shown that minimally processed soy appears to provide more potent and superior health benefits compared to those highly processed.

WE DO NOT KNOW … the extent to which infant soy formula does or does not affect a baby’s sexual, immune, or brain development.29 Soy is naturally rich in isoflavones, a plant compound with a structure similar to that of estrogen.32 However, the effects of the potential surplus of this hormone in infancy is unknown, and human studies have found little to no difference in development between babies fed soy- or cow’s-milk-based formula.33–35


Soy is widely grown and consumed across the globe and is an ingredient in many of the foods we eat.1,13-15,20 Part of its pervasiveness can be traced back to the ubiquity of its three main byproducts: oil, protein, and meal. Though research surrounding the nutritional benefits of soy is murky, experts generally agree that it is a healthy and nutrient-dense food source. Furthermore, few of the more well-known concerns are backed by strong science and many of the studies were conducted on animals. While more is needed to conclusively pin down the health effects of soy, those looking to add it to their diets would benefit from picking minimally processed products over highly processed ones.

Editor’s note. Consult with a qualified healthcare professional to determine if incorporating soy products  into your diet is best for you.


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  3. National Center for Complementary and Integrated Health website. Soy. Updated Dec 2020. Accessed 26 May 2022.
  4. World Wildlife website. Soy overview.,of%20protein%20and%20vegetable%20oils. Accessed 27 May 2022.
  5. Jin Z, Zhuang Q, Wang J, et al. The combined and separate impacts of climate extremes on the current and future US rainfed maize and soybean production under elevated CO2. Glob Chang Biol. 2017;23(7):2687–2704.
  6. Coleman K, Whitmore AP, Hassall KL, et al. The potential for soybean to diversify the production of plant-based protein in the UK. Sci Total Environ. 2021;767:144903.
  7. Arya H, Singh MB, Bhalla PL. Towards developing drought-smart soybeans. Front Plant Sci. 2021;12:750664.
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  9. United Soybean Board website. Improving S.S. soy quality, resilience. 10 Sep 2020. Accessed 27 May 2022.
  10. North Carolina Soybean Producers Association website. The life of a soybean. Accessed 27 May 2022.
  11. National Oilseed Processors Association website. Soybean composition. 7 Jul 2015. Accessed 27 May 2022.
  12. United States Department of Agriculture website. Economic Research Services. Oil crops sector at a glance. Updated 1 Apr 2022. Accessed 27 May 2022.
  13. Ashbridge DD. Erickson DE (ed). Practical Handbook of Soybean Processing and Utilization. Urbana (Illinois): AOCS Press; 1995:1-8:
  14. Huffington Post website. The top 10 foods you didn’t know contain soy. 29 Sep 2016. Accessed 27 May 2022.
  15. Better Health Channel website. Soybeans and soy foods. 2021. Https:// Accessed 27 May 2022.
  16. Michelfelder AJ. Soy: a complete source of protein. Am Fam Physician. 2009;79(1):43–47.
  17. Brennan D. The difference between complete and incomplete proteins. 1 Jun 2021. WebMD website. Accessed 27 May 2022.
  18. Harvard T.H. Chan School of Public Health website. The nutrition source—protein.,diet%20with%20healthy%20protein%20foods. Accessed 27 May 2022.
  19. Harvard T.H.. Chan School of Public Health website. Straight talk about soy. Accessed 27 May 2022.
  20. Physicians Committee for Responsible Medicine website. Soy and health. Accessed 27 May 2022.
  21. American Heart Association website. 2Soy-rich foods like tofu may help lower heart disease risk. 3 Mar 2020. Accessed 27 May 2022.
  22. Ma L, Liu G, Ding M, et al. Isoflavone Intake and the risk of coronary heart disease in US men and women: results from 3 prospective cohort studies. Circulation. 2020;141(14):1127–1137.
  23. United States Food and Drug Administration website. Statement from Susan Mayne, Ph.D., on proposal to revoke health claim that soy protein reduces risk of heart disease. Updated 23 Feb 2018. Accessed 27 May 2022.
  24. Lichtenstein AH, Appel LJ, et al. American Heart Association Nutrition Committee. Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee [published correction appears in Circulation. 2006;114(23):e629] [published correction appears in Circulation. 2006;114(1):e27]. Circulation. 2006;114(1):
  25. Wu AH, Ziegler RG, Nomura AM, et al. Soy intake and risk of breast cancer in Asians and Asian Americans. Am J Clin Nutr. 1998;68(6 Suppl):1437S–1443S.
  26. Wei Y, Lv J, Guo Y, et al. Soy intake and breast cancer risk: a prospective study of 300,000 Chinese women and a dose-response meta-analysis. Eur J Epidemiol. 2020;35(6):567–578.
  27. Bøhn T, Cuhra M, Traavik T, et al. Compositional differences in soybeans on the market: glyphosate accumulates in Roundup Ready GM soybeans. Food Chem. 2014;153:207–215.
  28. Bawa AS, Anilakumar KR. Genetically modified foods: safety, risks and public concerns-a review. J Food Sci Technol. 2013;50(6):1035–1046.
  29. Petre A. Is eating soy healthy or unhealthy? 27 Aug 2020. Healthline website. Accessed 27 May 2022.
  30. Ramdath DD, Padhi EM, Sarfaraz S, et al. Beyond the cholesterol-cowering effect of soy protein: a review of the effects of dietary soy and its constituents on risk factors for cardiovascular disease. Nutrients. 2017;9(4):324.
  31. Tokede OA, Onabanjo TA, Yansane A, et al. Soya products and serum lipids: a meta-analysis of randomised controlled trials. Br J Nutr. 2015;114(6):831–843.
  32. Yellayi S, Naaz A, Szewczykowski MA, et al. The phytoestrogen genistein induces thymic and immune changes: a human health concern?. Proc Natl Acad Sci USA. 2002;99(11):7616-–621.
  33. Petre A. Is soy formula safe for your baby? 25 Feb 2020. Healthline website. Accessed 27 May 2022.
  34. Testa I, Salvatori C, Di Cara G, et al. Soy-based infant formula: are phyto-oestrogens still in doubt? Front Nutr. 2018;5:110.
  35. Gilchrist JM, Moore MB, Andres A, et al. Ultrasonographic patterns of reproductive organs in infants fed soy formula: comparisons to infants fed breast milk and milk formula. J Pediatr. 2010;156(2):215–220.    

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