Stanols are substances that occur naturally in various plants. Their cholesterol-lowering effects were first observed in animals in the 1950s. Since then, a substantial amount of research suggests that plant stanols (usually modified into stanol esters) can help to lower cholesterol in individuals with normal or mildly to moderately elevated levels. Stanols are available in margarine spreads, salad dressings, and dietary supplement tablets.

Related substances called sterols or phytosterols (such as beta-sitosterol) and sterol esters appear to lower cholesterol in much the same manner as stanols.9,20,22,54,55,57-60

( Note: Use ofbeta-sitosterol for conditions other than high cholesterol is discussed in the beta-sitosterol article.)

Sterols are found in most plant foods. Stanols occur naturally in wood pulp, tall oil (a by-product of paper manufacturing), and soybean oil, and can also be manufactured from the sterols found in many foods. Stanol and sterol esters are manufactured by processing stanols or sterols with fatty acids from vegetable oils.3 Stanol/sterols and their esters are added to margarine spreads and salad dressings and are also available as dietary supplement tablets.