The Dangers of Plant Sterols

Plant sterols, also known as phytosterols, are compounds that naturally occur in fruits, vegetables and seeds. Some food manufacturers supplement their products with plant sterols because of their purported benefit to heart health. However, as recently as 2005, plant sterol supplementation came under fire as a potential risk factor for certain heart conditions.

Definition

• Plant sterols share a similar structure with cholesterol. For this reason they replace a portion of the cholesterol in the bloodstream, thereby reducing the levels of total cholesterol and LDL ("bad" cholesterol). Somewhere between 200 and 400 mg of sterols are consumed daily through regular, healthy consumption of plant-based foods.

Supplementation

• Because sterols were found to reduce the levels of total and bad cholesterol, the U.S. Food and Drug Administration authorized labels for foods containing sterols to state that the compounds may reduce the risk of coronary heart disease. In turn, products from snack bars to yogurts to orange juice have included sterol supplementation of multiple times the naturally occurring quantities.

Atherosclerosis

• Atherosclerosis is a condition in which plaque builds up on artery walls. Arteries carry blood to the heart and to other parts of the body, and built-up plaque reduces the flow of blood. While high cholesterol can lead to atherosclerosis, and sterols can lower cholesterol, a study published in the medical journal "Atherosclerosis" in 2006 reported that the built-up plaque in some patients with atherosclerosis was partially composed of sterols. In other words, sterols may contribute to atherosclerosis.

Aortic Stenosis

• Aortic stenosis happens when the aortic valve does not fully open, reducing blood flow to the body, causing chest pain and potentially worse. A Finnish study published in 2008, entitled "Accumulation of cholesterol precursors and plant sterols in human stenotic aortic valves," concluded that sterols build up in the aortic valve, reducing blood flow and therefore increasing an aortic stenosis risk.

Findings

• The two medical studies above have not generated any conclusions on the general safety of sterols, only on the effects sterols have on blood cholesterol and the composition of arterial plaques. Cardiologist Dr. William Davis does not recommend avoiding all sources of sterols, but only warns against processed foods boasting sterol supplementation. Foods with natural levels of plant sterols include olive oil, garbanzo beans, bananas and carrots.