Soy is a nutritional powerhouse and a staple in many diets around the world. Half a cup of soybeans have over 15g of protein, 5g of fiber, half your daily iron, ton of antioxidants and phytochemicals and other health promoting nutrients.
Young soybeans, edamame, can be steamed and eaten as is. Soybeans are also used to make healthy foods like tofu, tempeh, soy milk and miso. More processed form of soy include soy meats and cheeses. It's best to stick with the least processed versions of soy, like any other food.
Go for organic soy products that are least processed like edamame, tofu, tempeh, soy milk and miso.
Benefits of soy
Consumption of soy has been shown to reduce cholesterol levels, reduce cardiovascular disease risk, lower inflammation, decrease risk for chronic diseases, lower risk for bone fracture and even lower risk for many cancers, especially breast cancer.
Is Soy Estrogenic?
There is a common fear about "estrogens" in soy and the feminizing effects that may have. It's important to realize soy does not have the mammalian estrogen - those are found in animal products, especially dairy. Soy contains phytoestrogens - plant version of estrogen. Phytoestrogens in soy have been shown to be ~1000 times weaker. They also preferentially bind to different receptors in our body than the actual estrogen does. Due to this, soy actually has anti-estrogenic effects in places where excess estrogen may not be good for health like breast tissue. Meta-analyses have been done looking at if soy consumption does have a link with feminization, high estrogen levels or low testosterone for men and women and no such link has been found.
If one is worried about high estrogen consumption and its effects, they should be eliminating dairy from their diet as dairy naturally (without any added hormones) has mammalian estrogen.
References:
Ramdath, DD et al. Beyond the Cholesterol-Lowering 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):e324.
Wu, AH et al. Epidemiology of soy exposure and breast cancer risk. Br J Cancer. 2008;98(1):9-14.
Okekunle AP, Gao J, Wu X, Feng R, Sun C. Higher dietary soy intake appears inversely related to breast cancer risk independent of estrogen receptor breast cancer phenotypes. Heliyon. 2020 Jul 2;6(7):e04228.
Zhang, FF et al. Dietary isoflavone intake and all-cause mortality in breast cancer survivors: The Breast Cancer Family Registry. Cancer. 2017:2070-2079.
Hwang, YW et al. Soy food consumption and risk of prostate cancer: a meta-analysis of observational studies. Nutr Cancer. 2009;61(5):598-606.
Wu SH, Shu XO, Chow WH, et al. Soy food intake and circulating levels of inflammatory markers in Chinese Women. J Acad Nutr Diet. 2012;112:996-1004.
Pipe EA, Gobert CP, Capes SE, Darlington GA, Lampe JW, Duncan AM. Soy protein reduces serum LDL cholesterol and the LDL cholesterol: HDL cholesterol and apolipoprotein B:apolipoprotein A-I ratios in adults with type 2 diabetes. J Nutr. 2009;139:1700-1706.
Li SS, Blanco Mejia S, Lytvyn L, et al. Effect of plant protein on blood lipids: A systematic review and meta-analysis of randomized controlled trials. J Am Heart Assoc. 2017;6:E1-E51.
Koh WP, Wu AH, Wang R, et al. Gender-specific associations between soy and risk of hip fracture in the Singapore Chinese Health Study. Am J Epidemiol. 2009;170:901-909.
Zhang X, Shu XO, Li H, et al. Prospective cohort study of soy food consumption and risk of bone fracture among postmenopausal women. Arch Intern Med. 2005;165:1890-1895.
Messina, M. Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence. Fertil Steril. 2010;93(7):2095-2104.
Hamilton-Reeves, JM. et al. Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. Fertil Steril. 2010;94(3):997-1007.
Hooper, L. et al. Effects of soy protein and isoflavones on circulating hormone concentrations in pre- and post-menopausal women: a systematic review and meta-analysis. Human Reproduction Update. 2009;15(4):423-440.
McCarty, MF. Isoflavones made simple - Genistein's agonist activity for the beta-type estrogen receptor mediates their health benefits. Medical Hypothesis. 2006;66:1093-1114.
Mostrom, M & Evans, TJ. Phytoestrogens. Reproductive and Developmental Toxicology. 2011
Maruyama, K. et al. Exposure to exogenous estrogen through intake of commercial milk produced from pregnant cows. Pediatrics International. 2010;52:33-38.