Isoflavones, however, are only found in legumes such as clover, soy, lentils, chick peas, and beans. Most American women will have modest levels of lignans and flavones in their blood and very low levels of isoflavones. Due to a much higher consumption of legumes in Asia, blood levels of the isoflavone phytoestrogens are 20-30 times greater than those of American women. Consequently, the challenge for American women is getting enough isoflavones. Soy is great.
Red clover is even better.
Let's take a closer look at isoflavones. Of the considerable range of isoflavones consumed by humans, only a small proportion are estrogenic. Soy is a good source of Daidzein and Genistein, but contains virtually no Biochanin and Formononetin. You would need to eat other legumes such as chick peas to obtain Formononetin and Biochanin. However, red clover is one of the few plants that conveniently delivers all four main estrogenic isoflavones present in the human diet.