Broad Beans Versus Soybeans

Broad beans (Vicia faba) are also known as fava beans. They belong to the fabaceae family. Broad beans contain phytonutrients including the isoflavone group of molecules, although levels of total isoflavones (genistein and daidzein) are about one third of that in the soybean (total isoflavones in soybean seeds are ~60 mg per kg whereas in broad bean seeds they are they are ~25 mg per kg). Most of the lower isoflavone content of broad beans comes from the lower concentrations of daidzein (~40 mg per kg in soybeans compared to ~5 mg per kg in broad beans). Isoflavones are thought to play a role in deterring attack of host plants by pathogenic fungi. Broad beans also contain the plant sterol beta-sitosterol, which may contribute to their cholesterol lowering properties. The high fibre and high protein content of broad beans (as with all legumes) explains their ability to modulate plasma glucose levels favourably and may explain some of their health effects, including their ability to cause weight loss.

Kaufman, P. B., Duke, J. A., Brielmann, H., Boik, J. and Hoyt, J. E. 1997. A comparative survey of leguminous plants as sources of the isoflavones, genistein and daidzein: implications for human nutrition and health. The Journal of Alternative and Complementary Medicine. 3(1): 7-12