Daidzein is an isoflavone from soybeans and soy foods. People take it as a supplement, often with other soy isoflavones. Gut bacteria can turn daidzein into equol, a metabolite that drives many of its effects, but only some people carry the microbes that make this conversion reliably.
Daidzein supports bone maintenance and helps preserve cardiovascular function. It works through a mild estrogen-like activity. Because equol production depends on the gut microbiome, results differ from person to person.
A common daily dose runs between 20 and 50 mg. Many users take it with food, though absorption does not depend on a meal.