No. Soy intake does not raise or lower a man’s testosterone levels.
Derived from soybeans, soy is a high-protein substance found in many foods, such as edamame, tofu, soy flour, and soy milk. It can also be found in some supplements.
Many people add soy to their diets for health benefits. Research has shown that soy can lower cholesterol. Soy can also alleviate hot flashes for some menopausal women.
However, there have been some concerns that soy might lower a man’s testosterone levels. This is because the active ingredients in soy – isoflavones – are phytoestrogens – plant-based compounds that behave much like estrogens.
Estrogens are hormones that are heavily involved in a woman’s reproductive system. Men’s bodies produce estrogens too, but at much lower amounts.
Still, some men worry that consuming phytoestrogens may reduce their testosterone levels. Low testosterone can be linked to diminished sex drive, erectile dysfunction, reduced muscle mass, depression, fatigue, and osteoporosis.
In 2010, a group of American researchers from the University of Minnesota and Loma Linda University in California analyzed 47 studies that examined the relationship between soy and men’s sex hormones, including testosterone.
The researchers concluded that soy intake did not significantly affect testosterone levels.
“These results suggest that consumption of soy foods and isoflavone supplements would not result in the adverse effects associated with lower [testosterone] levels,” they wrote.
Men who are concerned about soy and their reproductive hormones should talk to their doctor.
In addition, men should know that testosterone’s synthesis begins with cholesterol. But this type of cholesterol comes from internal bodily sources and is not the same as dietary cholesterol. Therefore, cholesterol-lowering drugs and dietary changes should not affect the production of testosterone.