Plant sterols or stanols are synthesized only by the plants and they very similar in structure to human cholesterol. Stanols differ structurally from cholesterol by a methyl or ethyl group in their side chains that are not produced in the human body. These structural differences make them minimally absorbable by intestine. On the other hand, plant sterols generate an inhibition of cholesterol absorption.

Because many specialist claim that stanols can help reduce LDL cholesterol, manufacturers now begin fortify certain foods with these substances found in plants. The necessary amount of daily plant sterols for getting results is at least 2 grams. Fortified foods such as margarines and orange juices don't appear to affect levels of triglycerides or of "good" high-density lipoprotein (HDL) cholesterol. Nor do they interfere with the absorption of the fat-soluble vitamins (vitamins A, D, E and K) At the same time, studies concluded that the addition of plant sterols in foods helped further lower total cholesterol. Clinicians evaluated a nearly 10 percent reduction in low-density lipoprotein (LDL) cholesterol (LDL is called "bad" cholesterol).

Until then, long-term studies conformed absence of adverse effects in all individuals ingesting plant sterol esters. Therefore these products should be used for adult conditions requiring lowering of total and LDL cholesterol levels. However their use as a dietary addition in moderate to severely hypercholesterolemic children can be considered if the fat-soluble vitamin status is close monitored.

Recently, scientists at Washington University School of Medicine in St. Louis made a pill containing plant sterols. They suggests that this pill might be effective. and more safety.