What are the real effects of soy consumption in men? Find out if you can safely consume it or not and what are its advantages and disadvantages.

In recent years the consumption of soybeans and derivatives obtained from it has increased notably in many European countries, especially in our country. The reason must be found, above all, in that its consumption is being promoted in a notable and important way through various advertising campaigns, in which -for example- soy drink is sold as a suitable alternative to cow’s milk; becoming, therefore, an interesting option for people with lactose intolerance.

As you surely know, soy is a legume belonging precisely to the legume family (Fabaceae), scientifically known by the name of Glycine max.

Due to its multiple uses it is marketed throughout the world, thus becoming a popular food well known for centuries in countries such as China, Japan or Korea, and for some decades in the West as a result of the increase in products derived from it. It is, in fact, a food that has been cultivated for more than 3,000 years.

From a nutritional point of view, we are faced with a food with a high amount of vegetable proteins, omega 3 fatty acids, natural antioxidants, fiber, vitamins (especially vitamins of group B, highlighting the presence of vitamin B12, and vitamin K), and minerals (especially iron and magnesium). What’s more, its high content of essential amino acids is surprising.

Its main nutritional advantages are found in the fact that it is rich in protein, so that 100 grams of soy provide around 17 grams of protein. And although its consumption is advisable in many cases, and interesting benefits have been found regarding its consumption, its supposed not so positive effects make it a controversial food.

These supposed health effects leave us with a question as common as it is normal:  is soy safe for men? Can they consume it safely? And if so, how much?

What are the effects of soy consumption in men? Controversial results

Sperm reduction and sperm quality

A cross-sectional study, found in 2007 that the ingestion of soy and isoflavones reduced the concentration of sperm in men’s sperm.

According to the results obtained in this study, it was found that the inclusion of soy in the male diet affected those men who, prior to this consumption, maintained a normal or high sperm count in their sperm. It was even found that this effect was greater than the effects that obesity and excess weight had in obese men who also participated in the study.

However, other scientific studies carried out later have had conflicting results regarding soy consumption and sperm production. Furthermore, a meta-analysis, found that soy isoflavones in men did not alter either semen quality or hormone levels in the blood.

Erectile dysfunction

Scientific research found that a certain type of isoflavone found in soy, known by the name of daidzein, could negatively affect the erectile functions of the penis.

In this study it was found that the consumption of this isoflavone from youth could negatively affect the functioning of the penis in adulthood.

For example, rats consuming this isoflavone were found to have softer erections. However, testosterone was not significantly affected, nor did it affect the size of the penis or its normal growth.

But as the researchers themselves stated in the study’s publication, the studies in rats do not necessarily reflect the same results in humans.

It would help prevent prostate cancer

At some point that soy and its derivatives will help prevent cancer, in countries like Japan, thanks mainly to its isoflavone content. Thus, researchers concluded that the genistein present in soybeans would be of great help.

What’s more, preliminary research indicates that both soy protein and soy isoflavones may help slow the growth of PSA (prostate specific antigen) levels in men diagnosed with prostate cancer.

This would be due to the action of isoflavones as competition for estrogen receptors, especially in those mechanisms mainly involved so that prostate cancer does not progress.

Is it true that it lowers testosterone?

It is a quite controversial issue, and one that has made soy so much criticized in terms of the supposed safety of its consumption by men.

On the one hand, we must bear in mind that it is true that some scientific studies have associated the consumption of soy with the decrease in testosterone levels in men.  However, many of these studies confirm that a moderate consumption of soy in men has practically no effect on their testosterone.

For example, it is only necessary to relate the consumption of soy by Asian countries, large consumers of soy, in which it would be suggested that a high soy consumption would not affect sex hormones.

In this sense, a meta-analysis found that there was no evidence indicating that isoflavones or soy proteins increase estrogen or reduce testosterone, after analyzing the effect of consumption of derived products.

So, is soy consumption safe for men?

As many experts state, it is quite probable that most of the negative effects that soy causes on health (not only for men but also for women), is due to the presence of transgenic soy in many products derived from it.

In addition, it is always advisable to read the labels of the soy foods that we buy to ensure that it is an optimal source of soy protein, low in cholesterol, saturated fat and sugar.

On the other hand, as with any other food, excessive consumption is detrimental to health. But we must also bear in mind that few studies have actually shown that the consumption of high amounts of soy can have side effects in men.

Therefore, the recommendation is clear: always opt for products made from organically grown soybeans (in this way we make sure that we are not facing transgenic soybeans), and also not exceed their consumption. In this sense, between 1 to 2 servings of soy consumption is considered safe.


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