Many plant foods contain phytoestrogens — compounds that are similar to the hormone estrogen.
Some people believe that eating foods high in phytoestrogens may impair fertility in men, while others claim these compounds are healthy.
This evidence-based review looks into the science.
What Are Phytoestrogens?
Phytoestrogens are a group of naturally occurring compounds found in numerous plant foods.
They have various functions in plants. Many have strong antioxidant properties and some may play a role in the plants’ defense against infections.
They’re called “phytoestrogens” because their chemical structure resembles the structure of the sex hormone estrogen. The prefix “phyto” refers to plants.
Estrogen levels are higher in women than men.
This hormone is responsible for women’s fertility as well as maintaining feminine body features, but it also plays an important role in men.
Phytoestrogens’ similarity to estrogen means they can interact with estrogen receptors in cells. These receptors mediate estrogen’s functions within the body.
However, the effects of phytoestrogens are much weaker than those of estrogen. Also, not all phytoestrogens work the same. Some block estrogen’s effects, while others mimic its effects.
Phytoestrogens are found in most plant-derived foods in varying amounts. They all belong to a large group of plant compounds known as polyphenols.
Some of the most studied phytoestrogens include:
Lignans: Found in many fiber-packed plant foods, such as seeds, grains, nuts, fruits and berries. Flaxseeds are an especially rich source (9, 10).
Isoflavones: These are the most widely studied phytoestrogens. They’re abundant in soybeans and other legumes, and also present in berries, grains, nuts and wine.
Resveratrol: Found in fruits, berries, red wine, chocolate and peanuts. It is believed to be responsible for some of the health benefits of red wine.
Quercetin: This is one of the most common and abundant antioxidant flavonoids, found in numerous fruits, vegetables and grains.
Knowledge of phytoestrogens is gradually expanding, and scientists are regularly discovering new types.
While some researchers are concerned that high doses of phytoestrogens may disrupt the body’s hormonal balance, most studies have associated them with health benefits.
Are Phytoestrogens Healthy or Harmful?
Most studies indicate that phytoestrogens may benefit health.
However, a few studies suggest that a high intake of isoflavones may cause problems under certain circumstances.
The following two sections discuss the possible benefits and drawbacks of phytoestrogens.