Recently, drinking soy milk has become a trend, associated with beauty and preventing osteoporosis. But advocates are usually limited to women, and many people have asked me: Can men drink soy milk? I've heard that the isoflavones in soy milk can make men effeminate and even cause breast development. So, is it that men should drink milk, and women should drink soy milk?
Appropriate consumption of soy is beneficial and harmless for men
First, let's look at the reasoning behind why women are said to be suitable for drinking soy milk.
In fact, this is simply due to the isoflavones in soybeans. They have weak estrogenic activity. For menopausal women, they can partially compensate for the various problems caused by a drop in estrogen levels, such as decreased skin elasticity, accelerated loss of bone calcium, rapid heartbeat, facial flushing, and irritability.
Because the biological activity of phytoestrogens is only one-thousandth of that of estrogen, a cup of soy milk is not enough to cause a significant change in estrogen levels for young women. For young men, androgen levels are very high, and the phytoestrogens in a cup of soy milk cannot possibly reverse the hormonal balance, affect male sexual characteristics, or interfere with the normal development of boys. Conversely, when the intake of phytoestrogens is high, there is a slight inhibitory effect on androgens. Therefore, young men with high androgen levels may benefit from drinking some soy milk, as it can help alleviate problems caused by hormonal imbalance, such as acne.
Our country has a very long tradition of consuming soybeans. According to records from the Zhou Dynasty, soybeans were one of the ancient five grains, ranked before rice and wheat. This shows how important soybeans were in the diet at that time, with consumption far higher than it is now. Yet, were the men of that era not so valiant, strong, and heroic? We can imagine this from historical stories and the images of the Terracotta Army. The ancients said that soybeans "strengthen the spleen and benefit qi, and nourish qi and blood." For over two thousand years, there has never been a record of men developing poorly or becoming feminized from eating soybeans.
In fact, moderate consumption of soybeans is beneficial and harmless for men. A study published in the Journal of Nutrition in October 2007 showed that soy protein intake can reduce androgen receptor expression in the male prostate, which is completely consistent with multiple epidemiological studies showing that soy milk and soy products are beneficial for preventing prostate cancer in men.
The harm of milk and soy milk is related to the amount consumed
Conversely, excessive milk intake may increase the risk of prostate cancer. Studies have found a positive association between milk consumption and the risk of prostate cancer. This does not mean that drinking milk causes cancer, but that excessive milk (such as the equivalent of 3 glasses a day) may increase the risk of prostate cancer, just as eating too much meat can promote various cancers. At the same time, other studies have found that conjugated linoleic acid (CLA) in milk fat can inhibit various cancer cells in vitro and may have certain benefits for preventing breast cancer.
So, should we say the opposite: that drinking soy milk is beneficial for men, and drinking milk is beneficial for women? We cannot say that either. First, men and women have different constitutions. It is not true that what is beneficial for one man is equally good for all men. More importantly, the quantity of food has a huge impact on its health effects. A glass of milk is beneficial for nutritional balance, but that does not mean three glasses are equally beneficial; a glass of soy milk is good for preventing osteoporosis, but four glasses might have side effects—some doctors have found that many kidney stone patients have a history of drinking large amounts of soy milk.
The basic principle of toxicology is: the dose determines the toxicity. Food and medicine share the same origin, and every food has an optimal intake amount. When a food exceeds its reasonable intake, it can disrupt nutritional balance and even pose health risks. This is true for meat, milk, vegetables, and soy milk.
The Chinese Nutrition Society has already specified the reasonable intake of soybeans in the latest edition of the Dietary Guidelines—30 to 50 grams per day. At a ratio of 1 part beans to 10 parts water, 2 glasses of soy milk or 1 glass is equivalent to less than a small piece of tofu. At this amount, soy milk will not feminize Chinese men nor reduce their fertility.