The difference between soy lecithin & isoflavones

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Two particularly useful products derived from soybeans are soy lecithin and soy isoflavones. However, though both of these substances are extracted from the same plant, they have very different chemical characteristics and uses.

Chemical Makeup and Production

Soy lecithin is a fatty substance composed of phospholipids, phosphoric acid and fatty acids. It is a byproduct of the production of soybean oil, produced after the oil has been degummed -- had its fatty acids removed with the addition of a caustic substance. Isoflavones belong to a class of chemicals called polyphenols. The particular isoflavones found in soybeans are genistein and daidzein. Soy isoflavones are found in and extracted directly from the soybean itself.


Soy lecithin is used primarily as an emulsifier in several commercial food products, including chocolate bars, salad dressing and ice cream. It binds the components of food products together and keeps them from separating during long storage. It is also available in pill form as a natural supplement. Soy isoflavones are occasionally used by doctors as a method of oestrogen replacement.

Positive Health Effects

Soy lecithin contains choline. Choline is an important nutrient for human beings. It assists in the tissue growth and function of certain organs, such as the brain, liver and kidneys. Pregnant women often take choline for proper fetal development. Isoflavones, on the other hand, are solely a hormone replacement for women during menopause. They reduce the unwelcome symptoms that accompany menopause, such as hot flushes and mood changes.

Harmful Health Effects and Warnings

Soy lecithin can cause allergic reactions in those who are extremely allergic to soybeans. Soy-derived lecithin is also considered kosher in most Jewish traditions, however some Ashkenazi Jews will not consume lecithin during Passover. The soy isoflavone genistein can inhibit the formation of blood vessels.