Many fruits, vegetables and whole grains contain a chemical compound called sterols. Sterols are plant fat, similar to cholesterol in humans, and exist within plants in trace amounts. The human body requires a certain amount of cholesterol to aid in cellular growth and management. Plants use sterols in a similar manner for cell expansion, fertility and propagation. In recent years, sterols have been used as a supplement to aid in controlling cholesterol levels in humans.
The three major types of sterols in plants are sitosterol, stimasterol and campesterol. In the 1950s, research in plant biology led to the discovery of these compounds, and it was discerned that adding sitosterol to the feed of cholesterol-fed chickens aided in controlling the animals' cholesterol levels. By the 1980s, sterols were introduced into food products such as margarine and cooking oils.
Plant sterols, collectively referred to as phytosterols, occur naturally in raw foods, with fruits and vegetables exhibiting higher levels than whole grains and legumes. The role of sterols in cellular production and management includes processing unsaturated and saturated fats within the plant, which is then eliminated through plant respiration.
The sterols, when consumed by humans, work in conjunction with the circulatory and digestive system to process cholesterol. Phytosterols have a natural capacity for reducing and eliminating unneeded fat cells within the human circulatory system and directing them to the liver for disposal, thus lowering the level of bad cholesterol in the human body.
Phytosterols are, essentially, related to cholesterol, and when ingested by humans, work to block the absorption of cholesterol. This attribute makes sterols a viable food additive and supplement for those needing to control cholesterol levels. Sterols are found in brand name margarines, orange juice and soy snacks. Multivitamins and similar supplements have also been fortified with phytosterols.
The ingestion of foods high in sterol content, along with supplements, may aid those with slightly elevated levels of cholesterol. When cholesterol levels are significantly indicative of risk for heart disease, with levels at and over 240, prescription medication may be necessary, warns Dr. Tim Johnson in the article "Do Cholesterol Lowering Foods Really Work?" posted on Medical News Today.com. He also adds, "There is some evidence that these plant sterols can reduce the absorption of certain vitamins like vitamin A and E which may interfere with the prevention of heart disease often attributed to these vitamins."