A review of 15 studies into the influence of soy proteins or isoflavones on male hormones has found no evidence of an estrogen-like effect.
Soy has garnered attention as a healthy source of protein, and has been linked to a multitude of health benefits, including protection from breast cancer, prostate cancer, menopausal symptoms and heart disease. But some studies have suggested that soy isoflavones could affect male testosterone levels, due to their similarity in chemical structure to estrogen, which means they bind to estrogen receptors and can exert estrogen-like effects.
The meta-analysis of data was carried out by researchers at the University of Minnesota who wrote: “Because of the increasing popularity of soy foods and the availability of isoflavone supplements, there is an important public health need to understand the impact of soy isoflavones on reproductive hormone levels in men.”
Low levels of testosterone in men can lead to depressed mood, loss of muscle mass, weight gain, erectile dysfunction and osteoporosis.
The study concluded: “These results suggest that consumption of soy foods or isoflavone supplements would not result in the adverse effects associated with lower [testosterone] levels.”