Can Phytoestrogens Adversely Impact A Man’s Health?

Phytoestrogens, otherwise known as plant-based estrogens, form a very puzzling part of nutrition. It’s very hard to tell whether these are good for health or not. In some research papers, they have been known to cause certain health problems, while on the other hand, other studies claim that they can fight certain cancers.

While the effects of phytoestrogens may seem conflicting, it is still very important to understand their role in your health, for they are key in maintaining appropriate hormonal levels all through your life.


Here’s an attempt at separating fact from fiction and looking at the positives and negatives of these mysterious plant estrogens.

What Are Phytoestrogens?

Phytoestrogens are naturally occurring compounds found in a large number of plant foods.


Phytoestrogens are naturally occurring compounds found in a large number of plant foods. They serve a variety of functions in plants like being a good provider of antioxidants and sometimes, even play a major role in the plants’ defense against infections.

Their chemical structure is similar to that of the human sex hormone estrogen, while the prefix “phyto” refers to plants. For this reason, they are called phytoestrogens.


Over the years, research has investigated and studied various phytoestrogens such as:

  • Lignans: These are found in fiber-packed plant foods like nuts, seeds, grains, berries, and fruits. Flaxseeds are a very good source of lignans.
  • Isoflavones: Commonly found in legumes like soybeans, berries, nuts, grains, and wine, these are the most widely studied phytoestrogens.
  • Resveratrol: This is found in berries, fruits, peanuts, and chocolate. It is also found in wine and is known to be responsible for some of the health benefits of red wine.
  • Quercetin: This is one of the most commonly found antioxidant flavonoids, and is present in most grains, fruits, and vegetables.

Phytoestrogens And Men

While a few phytoestrogens mimic the effects of estrogen, there are also some that are known to block these effects.


It is a well-known fact that estrogen levels are much higher in women than in men and that it is responsible for a woman’s fertility as well as contributing to the development of the feminine body features. However, this hormone also plays an important role in men.

Too little estrogen in men can increase the risk of osteoporosis and may even lead to bone fractures. On the other hand, higher than normal levels of estrogen may double a man’s risk of stroke, can make him more susceptible to coronary artery disease, and may even place him at a higher risk for prostate cancer, especially if there is low free testosterone in the blood levels.


The structural similarity between phytoestrogens and human estrogen means these plant-based compounds can interact with the estrogen cell receptors in the body. This would mean that phytoestrogens can help these cell receptors regulate the estrogen levels and functions within the body, thus keeping the hormone at optimum levels.

It is important to note, however, that the effects of phytoestrogens are much weaker than those of estrogen. In addition to this, not all phytoestrogens work the same way. So even though there quite a few phytoestrogens that mimic the effects of estrogen, there are also some that are known to block them.


The Health Benefits Of Phytoestrogens

Phytoestrogens are linked to health benefits like reduced blood pressure and lower levels of bad cholesterol.

The knowledge of phytoestrogens is slowly expanding, with scientists striving to discover new types. While many researchers are concerned that the body’s hormonal balance may be disrupted by high doses of phytoestrogens, most studies have associated them with numerous health benefits such as:

  • Reduced Blood Pressure: Quercetin and resveratrol supplements may bring down blood pressure levels.
  • Improved Blood Sugar Control: Flaxseed lignans, soy isoflavones, and resveratrol may benefit help regulate blood sugar levels.
  • Reduced Risk Of Prostate Cancer: It is suggested that isoflavone supplements may bring down the risk of prostate cancer, but there is no strong evidence to state the same.
  • Lower Cholesterol Levels: Soy isoflavone supplements may bring down total cholesterol levels and “bad” low-density lipoprotein (LDL) cholesterol.
  • Reduces Inflammation: Lignans and soy isoflavones may reduce levels of the inflammatory marker – C-reactive proteins (CRP), in postmenopausal women with high CRP levels.

The Adverse Effects Of Phytoestrogens

Phytoestrogens are sometimes believed to obstruct the body’s hormonal functions when consumed in high doses

Some scientists are concerned that a high intake of phytoestrogens may disrupt the body’s hormonal balance.

Many researchers have classified phytoestrogens as endocrine disruptors, or chemicals that may obstruct the body’s hormonal functions when consumed in sufficiently high doses.

A few studies suggest that a high consumption of isoflavones from soy-based infant formulas may hinder thyroid function when paired with poor iodine intake. They also indicate that isoflavones may further suppress the functions of the thyroid in those who suffer from hypothyroidism.

Most studies in healthy people, however, haven’t found any significant evidence of adverse health effects of isoflavones on thyroid function, or that of other common phytoestrogens on the general health of men.

Do Phytoestrogens Impair Male Fertility?

Most studies have failed to come up with concrete proof as to whether isoflavones are responsible for male infertility.

It has been a long debate whether excessive exposure to phytoestrogens can impair or reduce male fertility.

While a study in cheetahs showed that consuming large amounts of phytoestrogens resulted in impairing the fertility of the males, scientists have pointed out that these plant-based estrogens probably affect carnivores like cheetahs differently from how they would otherwise affect omnivores like humans.1

An analysis of 15 studies declared that soy isoflavones, be it in food or supplement form, do not interfere with the testosterone levels in men. Another study showed that consuming 40 grams of isoflavone supplements each day for two months did not affect men’s semen volume or quality.

There was, however, another study that showed that a high consumption of isoflavones-rich soy, was associated with a reduced sperm count, but the researchers failed to find evidence if the isoflavones themselves were responsible for this.

Most of the evidence leans in favor of isoflavones not being responsible for adversely affecting men’s fertility. Yet, we still know very little about the effects of other common phytoestrogens or about the long-term consumption of high-dose supplements in men.

The Bottom Line

The benefits of eating foods rich in phytoestrogens outweigh the possible health hazards by a large margin.

There is no strong evidence to show phytoestrogens being bad for men.

Phytoestrogens are widely found in many healthy plant foods, and the benefits of eating these foods outweigh the possible health hazards by a large margin. If you want to be cautious, limit your overall intake and consult with your dietitian or doctor before adding or completely excluding phytoestrogens from your diet.