Equol

What is equol?

Equol is an isoflavonoid that exists as 2 enantiomers, R-equol and S-equol (R). It can be found in vegetables such as beans, cabbage and lettuce (R, R). It is also present in cow's milk, due to dairy cows being fed a diet rich in isoflavones (R). R-equol and S-equol can also be synthesised selectively, enabling their production on a large scale (R, R).

In humans, S-equol is produced from the metabolism of the soy isoflavone daidzein by microbes in the intestine (R, R), though less efficiently compared to other animals (R). In addition, only 25 to 30% of the Western population and 50 to 60% of the Asian population is able to metabolise equol from daidzein, probably because of the different compositions of bacteria in the gut (R, R) or differences in the diet (R, R).

Does equol get absorbed?

Equol has been shown to penetrate human skin in vitro. After a single application, about 11% was of the applied dose was detected in the epidermis and 0.3% in the dermis. Equol appears to be sequestered by keratinocytes in the epidermis, which release it slowly to the dermis over time (R).

What happens after equol is absorbed?

Equol is a phytoestrogen that has binding affinity for estrogen receptors. S-equol has low affinity for estrogen receptor α and binds estrogen receptor β with 20% the affinity of estradiol. R-equol, on the other hand, has weak affinities for both estrogen receptors α and β (R).