Phytosterols are plant-derived compounds structurally related to mammalian cell-derived cholesterol that function as essential constituents of plant cell membranes. Phytosterols are composed of 90% sterols and 10% stanols – and scientists maintain the plant ingredients lower cholesterol absorption in the small intestine by competing with it. Both classes of phytosterol are naturally occurring and can be found in a variety of medicinal plants and foods, including nuts, vegetable oils, seeds, and cereals.
Phytosterols act through multiple mechanisms of action, including inhibition of carcinogen production, cancer-cell growth, angiogenesis, invasion and metastasis, and through the promotion of apoptosis of cancer cells. In addition to altering cell-membrane structure and function, phytosterols promote apoptosis by lowering blood cholesterol levels.