Cholesterol is a sterol produced by humans and other mammals. Phytosterols, more commonly called plant sterols, are produced by the fatty parts of plants. The human intestine does not absorb plant sterols well, and they are recommended as a dietary means of reducing the levels of cholesterol in the blood, a major contributor to coronary heart disease and high blood pressure. Beans are a major dietary source of plant sterols.
Plant Sterol Effects
The physical structure of plant sterol resembles that of cholesterol. Plant sterols are known to absorb LDL (low density lipid) cholesterol. LDL cholesterol is the so-called "bad" cholesterol that collects in arteries and drives up blood pressure.
Plant Sterol Action
The human liver produces 20 to 25 percent of the body's daily need of cholesterol. Plant sterols lower the amount of cholesterol entering the blood stream through the small intestine. When this happens, the body draws on stored reserves of cholesterol. This decreases the level of cholesterol in the blood, reducing stress on the heart and lowering blood pressure.
Legumes, including garbanzos, lentils, limas, dried peas, soy beans, and white, red and black beans, are all recommended as among the better dietary sources of plant sterols. Peanuts, too, are a good source; peanuts are legumes, not nuts. Oleiferous plants, including nuts and seeds that yield oil, are the best sources of plant sterols.
Soybeans are the richest source of plant sterols in beans. High levels of sterols are found in cooking oil made from soybeans, in soy milk and in tofu, a curd made of soybeans.
Studies have led the European Union to assume that plant sterols in foods help prevent colon cancer. The Linus Pauling Institute at Oregon State University (OSU) reports that a few clinical studies suggest that eating foods with plant sterols decreases the risk of some cancers, but the studies are not conclusive. OSU researchers say studies also suggest that relatively low doses of plant sterols can improve the flow of urine obstructed by the enlargement of the prostate gland, but more studies are needed.