How Do Isoflavones Work?

Natural plant compounds interact with estrogen receptors

Part of a class called phytoestrogens, isoflavones are naturally occurring plant compounds that can show some of the same characteristics as human hormones.

How do they work? Phytoestrogens like isoflavones, lignans, and coumestans are structurally similar to human estrogen. Often called selective estrogen receptor modulators, isoflavones are known to interact with estrogen receptors in humans (although they can also act quite differently than estrogen) to produce similar effects. This activity gives isoflavones the ability to ease the transition through menopause, reducing symptoms like hot flashes.

In addition, preliminary research suggests soy isoflavones may help keep arteries flexible and responsive. How? By stimulating receptors in the arterial walls to produce nitric oxide. Nitric oxide then signals the arteries to relax, improving their reactivity.

Isoflavones may also work in other areas of the body, such as helping to maintain healthy bones by interacting with cells. Bones are constantly being remodeled, or kept healthy, by two processes. One breaks down the bone, releasing minerals. The other then rebuilds the bone and replaces minerals. Before menopause, hormones help balance these two processes. During menopause, the process that breaks down bone occurs more often than the bone rebuilding process, due to rapid estrogen loss. Soy isoflavones help rebalance the two processes to help slow bone loss.

Another benefit of isoflavones: They are readily absorbed in the gut, and they’re almost completely metabolized and eliminated within 24 hours of consumption.

Though many different isoflavones exist, the primary types in soy are genistein, daidzein, and glycitein. In the glucoside form, genistein and daidzein are the isoflavones that provide the most noted benefits for people and the main isoflavones found in Novasoy® soy isoflavones.