CLAIM:
Soy is a safe and healthy source of protein for men and does not cause gynecomastia (man boobs) or increase oestrogen levels. It can be consumed regularly without harming hormonal balance.
FACT:
Current scientific evidence and expert opinion show that soybean does not cause gynecomastia or increase oestrogen levels in men when consumed in normal amounts. Large studies consistently find no hormonal effects, while rare cases are linked only to excessive intake. Moderation and a balanced diet remain key.
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In a viral Instagram reel posted by popular influencer Ranveer Allahbadia, also known as BeerBiceps, who has over 5 million followers on Instagram, the discussion turns to a common concern around soy consumption and male health. In the reel, he is seen in conversation with Sr. Gastroenterologist and Hepatologist Dr Shubham Vatsya, where the two address whether soy can lead to hormonal changes or “man boobs.”
During the interaction, Dr Vatsya states that soy is a strong source of vegetarian protein and dismisses concerns linking it to gynecomastia. “Soya is a very good source of vegetarian protein. Soya does not cause man boobs. Soya does not increase oestrogen,” he says, adding that existing research supports its safe consumption in men. When Ranveer asks if soy can be consumed daily, the doctor responds, “You can go easily,” suggesting there is no harm in regular intake.
The reel has managed to gain massive traction, clocking over 1.3 million views, along with 31.4k likes and 14.2k shares, sparking widespread conversation around soy, hormones, and men’s health.
Research: Does soybean cause enlarged breasts in men?
Evidence indicates that while extremely high or unusual consumption may rarely be linked to adverse effects in isolated cases, typical dietary intake of soy does not increase oestrogen levels or cause gynecomastia (man boobs) in men.
A 2010 review of published clinical studies examining soy isoflavones and male health found no evidence of feminising effects. The analysis, based on a Medline literature review and cross-referenced data, reported that “neither isoflavone supplements nor isoflavone-rich soy affect total or free testosterone (T) levels.” It further noted that “there is essentially no evidence… that isoflavone exposure affects circulating estrogen levels in men.” Importantly, the review concluded that “isoflavones do not exert feminizing effects on men at intake levels equal to and even considerably higher than are typical for Asian males.”
Building on this, a 2021 updated and expanded meta-analysis of 41 studies involving over 1,700 men reinforced these findings. Researchers analysed the impact of soy protein and isoflavones on testosterone, oestrogen, and related hormones. The study found that “regardless of dose and study duration, neither soy protein nor isoflavone exposure affects TT, FT, E2 or E1 levels in men.” This strengthens the evidence that soy consumption does not disrupt hormonal balance in males.
However, isolated case reports do exist. A 2020 case study documented an 8-year-old boy who developed gynecomastia linked to excessive soy intake. The authors noted that “soy products… can contain high levels of phytoestrogens, which have been documented in limited case studies to contribute to abnormal development of breast tissue.” Notably, the condition completely resolved after soy was removed from the diet, suggesting a reversible and rare response rather than a general risk.
More recent research also helps clarify how soy behaves in the body. A 2025 systematic review and meta-analysis of 40 randomized trials found that soy isoflavones “had no statistically significant effect on any measure of estrogenicity.” The study concluded that these compounds likely act as selective modulators rather than mimicking human estrogen, stating that “soy isoflavones do not exhibit estrogenic effects… differing clinically from the hormone estrogen.”
What experts say?
Dietitian Rajeshwari Panda, HOD – Nutrition & Dietetics Department, Fortis Hospital, Mulund, says there is no strong scientific evidence to support the claim that soybeans cause gynecomastia.
She explains that gynecomastia is primarily linked to hormonal imbalance, particularly when the oestrogen-to-testosterone ratio is higher. “Gynaecomastia is typically caused by hormonal imbalance; when oestrogen is more than testosterone,” she says, adding that factors such as obesity, certain medications, alcohol use, and hormonal disorders are more established causes.
Panda notes that while soy contains phytoestrogens, they are far weaker than human oestrogen. “It does mimic human oestrogen, but it is not as strong - it is 100 to 1000 times less potent than human oestrogen,” she explains. Because of this, she says, soy cannot be directly blamed for causing gynecomastia based on current evidence.
She also points out that the rare cases linking soy to breast enlargement are usually associated with excessive intake, often through supplements or very high consumption. “Some case studies show this with high soy intake, but these are rare and not strong enough to be considered evidence-based,” she says.
On daily consumption, Panda advises moderation rather than elimination. While soy can be part of a healthy diet, overconsumption is not recommended. “If something is labelled as good, you cannot overconsume it; that becomes toxic,” she says, stressing the importance of dietary variety.
She recommends limiting intake to moderate amounts. “You can consume it like other foods, but in limited portions,” she says. For regular intake, she suggests small quantities of around 25 grams per day, or consuming soy products two to three times a week.
This story is done in collaboration with First Check, which is the health journalism vertical of DataLEADS
