Is it true that drinking soy milk can cause men’s breasts to enlarge?
The idea is all over social media, but the answer is almost certainly no. “It’s highly unlikely that drinking soy milk promotes breast growth in men,” says Donald Hensrud, associate professor of nutrition and preventive medicine at the Mayo Clinic College of Medicine. “I haven’t seen good evidence that soy milk has any feminizing effects on men.”
Concerns regarding soy’s effect on men probably arose because soybeans and other legumes contain isoflavones. These are phytoestrogens, or estrogen compounds structurally similar to human estrogen. However, “they have different biological properties than human estrogen and don’t promote harmful estrogen effects on the body,” Hensrud says. “In fact, they may be protective.”
Studies generally do not support the notion that drinking soy milk will cause men to grow breasts or experience any other feminizing effects. Studies also refute the notion that soy increases the risk of breast cancer in women.
“I haven’t seen any data that leads me to believe that drinking soy milk or eating soy products promotes feminization in men, meaning breast growth, or any similar adverse health effects, such as breast cancer, in women,” says David Jenkins, university professor in the departments of nutritional sciences and medicine, Temerty Faculty of Medicine, at the University of Toronto. “I recommend soy intake to my patients — both sexes. I don’t think it has any ill effects.” He added that no major health organization has warned of any dangers associated with soy consumption.
At least two early studies each described a single case of soy consumption linked to feminizing effects in men, among them enlarged breasts, erectile dysfunction, and decreased libido. But experts pointed out that the two subjects each consumed unusually high amounts of soy — in one instance, three quarts of soy milk a day — which is many times the intake in the average diet.
“That is a very large amount of soy milk on a consistent basis — most people don’t drink that much water daily,” Hensrud says. “These are two unusual cases, and they are not representative of the overall evidence on soy phytoestrogens.”
“Breast growth — gynecomastia — does occur occasionally in men and adolescent males,” he says, referring to other causes of gynecomastia in young men. “Most importantly, there is strong evidence that soy intake provides numerous health benefits with little risk.”
Many studies have also found that soy milk and other soy products may lower the risk of breast cancer, possibly accounting for the low incidence of breast cancer among Japanese women, whose traditional diets are heavy in soy. Soy intake also may lower the risk of breast cancer recurrence in women, according to studies.
Women who have estrogen-positive breast cancer may worry regarding soy, but Hensrud says data does not point to a greater risk. Other research indicates that breast cancer rates rise among Japanese women who reduce their soy consumption and adopt a Western diet.
Moreover, soy milk can have cardiovascular benefits by reducing blood pressure, inflammation, and low-density lipoprotein (the bad) cholesterol, according to studies. Additional research shows soy appears to reduce the risk of prostate cancer and might prevent memory loss associated with aging and cognitive impairment.
What else you should know
Soy milk is a processed food that may contain added sugar, flavorings, and other ingredients. Also, those who have a soy allergy should avoid it.
In addition to isoflavones, soy foods are rich in B vitamins, fiber, potassium, and magnesium. Also, unlike some plant proteins, soy protein contains all nine essential amino acids, making it a complete protein. Soy foods can be unfermented or fermented, the latter meaning it has been cultured with beneficial bacteria, yeast, or mold.
“Fermented soy milk may have even more health benefits, similar to other fermented foods,” Hensrud says.
Analysis
The debate around the effects of soy milk on men’s breasts has gained significant attention on social media platforms. However, experts like Donald Hensrud and David Jenkins emphasize that there is no substantial evidence to support the claim that soy milk promotes breast growth in men or feminizing effects. The presence of isoflavones in soy, which are phytoestrogens, may have led to concerns, but studies indicate that these compounds have different properties than human estrogen and are unlikely to cause harm. In fact, they may have protective effects.
While a few early studies reported cases of feminizing effects in men due to excessive soy consumption, these instances involved unusually high intake, far beyond what is typically consumed in a regular diet. Therefore, they cannot be considered representative of the overall evidence on soy phytoestrogens.
On the contrary, numerous studies highlight the potential health benefits of soy milk and soy products. They have been associated with a reduced risk of breast cancer, lower blood pressure, decreased inflammation, and improved cholesterol levels. Soy intake may also lower the risk of breast cancer recurrence and prostate cancer. The traditional Japanese diet, which includes a significant amount of soy, may contribute to the low incidence of breast cancer among Japanese women.
While concerns may arise for women with estrogen-positive breast cancer, data does not suggest an increased risk associated with soy consumption. In fact, breast cancer rates have been observed to rise among Japanese women who reduce their soy intake and adopt a Western diet.
It is important to note that soy milk, like any processed food, may contain added ingredients such as sugar and flavorings. Individuals with soy allergies should avoid it. However, soy foods, in their unfermented or fermented forms, offer additional nutritional benefits. They are rich in B vitamins, fiber, potassium, and magnesium. Moreover, soy protein is a complete protein, containing all nine essential amino acids. Fermented soy milk, similar to other fermented foods, may provide even more health benefits.
Overall, the evidence suggests that soy milk is a safe and nutritious option for both men and women, offering potential health advantages. It is crucial to rely on scientific research and the expertise of health professionals when evaluating claims and notions spread through social media and other platforms.
