Plant Sterol Definition

Plant sterols are chemical compounds found in plants and are similar to cholesterol in their structure and function. Plant sterols were highly prevalent in early human diets that were heavily plant-based. They are currently the focus of cholesterol and cancer cell research, according to the Linus Pauling Institute. Although more research is needed about their health benefits, plant sterol products are marketed as cholesterol modulating supplements.

Absorption

• Plant sterols are consumed from plant-based foods. As they are processed by the digestive tract, plant sterols enter the intestinal lumen, an area of high nutrient absorption, and interact with digestive chemicals and enzymes. The plant sterols are transported into the liver, where they are processed into bile and aid in the digestive process.

Action

• Plant sterols inhibit the absorption of cholesterol while they are in the intestinal lumen. The body responds to decreased cholesterol absorption by making more cholesterol. However, the plant sterols inhibit cholesterol absorption in amounts that are high enough to result in lower LDL cholesterol levels, according to the Linus Pauling Institute.

Sources

• All plants contain plant sterols. High amounts of plant sterols are found in unrefined oils from plant sources. Wheat germ, peanuts, almonds and wheat bran have high levels of plant sterols. Oils high in plant sterols include sesame, corn, canola and olive. Additionally, several commercial spreads, salad dressings and dairy products have been enriched with plant sterols.

Additional Health Benefits

• Plant sterols may play a role in treating cancer. Cancer cells do not respond to cell death signals and continue to grow and multiply. Sitosterol, a type of plant sterol, has been shown to cause cell death in various forms of cultured cancer cells. Plant sterols may also decrease the inflammation producing action of immune system cells. Symptoms of benign prostatic hyperplasia have been reduced from plant sterol supplementation, according to the Linus Pauling Institute.

Supplemental Dosage

• Dosages for plant sterol supplementation range from 60 mg per day to 2,000 mg per day, according to the Linus Pauling Institute. The higher dosages are recommended on supplements marketed for lowering cholesterol. Plant sterols are better absorbed when taken with a meal containing fat. Supplemental plant sterols are often marketed as beta-sitosterol.

Safety and Side Effects

• Adverse reactions to plant sterols are rare but include diarrhea, nausea, indigestion and constipation. Individuals with sitosterolemia should avoid plant sterols, as they are unable to absorb the sterols in the intestinal tract. Pregnant and lactating women are also recommended to avoid plant sterol supplements and enriched foods, according to the Linus Pauling Institute. The Scientific committee on Foods of the European Union recommends that dosages not exceed 3,000 mg per day, as the effects of such high doses are unknown.