Soya Consumption and Sex in Men

“Soya foods cause man boobs”

“Soya intake reduces sex drive in men”

“Soya intake reduces fertility in men”

These are just some of the myths circulating round the media targeted at men’s health.

Looking at the research closely is essential before making radical conclusions about your diet, and whether or not to include soy-based foods.

When reading an article, ask yourself “Was the research quoted carried out in humans?”  AND “Was the research approved by any scientific journal for publication?”

Always check the source of the research.  Also look at the nature of the “research” conducted (number of studies carried out, number of participants in any given/cited study: 8 participants in a “conclusive” study does not constitute a good, scientific study).

In this article, we cover some of the myths surrounding the intake of soya products and their influence on male sex hormones.



Studies done in male rats show that high doses of phytoestrogens* (refer to discussion on phytoestrogens below) given or injected in these rats (amount equivalent to 2l soya milk in humans) may impair the rat’s ability to produce offspring. BUT the same effect HAS NOT been found in male humans. Since many of the concerns related to soy come from studies in rats and mice, it is important to recognize that rodents metabolize soy isoflavones differently than humans, essentially making these studies irrelevant.

Interestingly, while individual cases of sex hormone changes in men eating EXTREMELY HIGH doses of soy have been reported, these effects were reversed when the doses of soy were reduced.

The journal “Fertility and Sterility” published a review article in 2010 which concluded that “neither isoflavones supplements nor isoflavones-rich soy (food) affect total or free testosterone levels” and that there is essentially no evidence from nine identified clinical studies that isoflavones exposure affects circulating oestrogen levels in men”.



Testosterone levels affect sexual desire, so anything that depletes these hormones in men can eventually zap their desire for sex. Thus concerns have been raised regarding soya intake and its effect on potentially lowering testosterone levels and thus reducing sexual desire.

Look at the research! The main bulk of research shows that soy consumption is highly unlikely to cause reproductive abnormalities in men.

2 large studies showed that men taking in regular doses of soya (from food or soya milk) show zero changes in testosterone levels; and no effects on testicular or ejaculate volume or sperm concentration, count or mobility.


PHYTO means “plant”

PHYTOESTROGENS are “plant oestrogens”

These fall under a broader category of substances in food called PHYTOCHEMICALS. PHYTOCHEMICALS = compounds in plants (fruits, vegetables and legumes including soy beans) that do not contribute nutrients, but do contain biologically active components that affect our bodies in healthful ways. Phytoestrogens, found most concentrated in soy foods, have been positively linked in extensive studies done globally, to lower incidences of certain cancers (including prostate cancer), heart health, relieving menopausal symptoms in women, and potentially lowering the risk of osteoporosis.

Soya is a rich and primary dietary source of the phytoestrogen class known as ISOFLAVONES, which are present in relatively large amounts in virtually all soy foods. Isoflavones are structurally similar to oestrogen and mimic its effect in the body.

Typical Phytoestrogen content in some soy foods:

FoodAmountPhytoestrogen content
Soybeans½ cup 40mg
Soy flour ¼ cup25mg
Tofu½ cup40mg
Soy milk1 cup40mg


SOY ISOFLAVONES have been shown repeatedly in extensive global research to have numerous beneficial effects on bone, brain, prostate and cardiovascular health in men. Concerns raised that consumption of these dietary oestrogens might cause abnormalities in sex drive, feminization in men, lower testosterone levels and semen quality, and adversely affect fertility in adult men, are completely unfounded. In fact studies investigating hormonal effects of soya consumption by men suggest NO EFFECTS on sexual function.

So men, eat your tofu, soya-based porridges – drink your soya milk! And enjoy the health benefits of soy consumption without fearing negative effects on your sex drive!

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