Plant sterols, phytosterols, are cholesterol-like compounds that are found mostly in vegetable oils, nuts and legumes. There are about 44 sterols known to exist in plants. The most abundant phytosterols are, however, beta-sitosterol, campesterol, and stigmasterol.

Phytosterols have the same function as cholesterol in the body. Cholesterol is necessary component of cell membrane and required for the synthesis of sex hormones and vitamins. However, when cholesterol is high in the blood (serum) it is associated with heart diseases. Diet rich in phytosterols is known to reduce serum cholesterol. Several supplements provide various dosage levels of these important plant sterols.