Plant Sterols and Plant Stanols

Plant Sterols and Plant Stanols represent a group of compounds that are an essential constituent of cell membranes in animals and plants. Cholesterol is actually a sterol of human cells, whereas phytosterols are produced by plants.

The most common plant sterols are sitosterol, campesterol, and stigmasterol. Plant sterols, although structurally similar to cholesterol, are not synthesized by the human body and are very poorly absorbed. The specific plant sterols that are currently incorporated into foods and supplements are extracted from soybean oil. The plant sterols, currently incorporated into foods, are esterified to unsaturated fatty acids (creating sterol esters) to increase lipid solubility, thus allowing maximal incorporation into a limited amount of fat. Some plant sterols currently available are saturated, to form the stanol derivatives, which are also effective at lowering cholesterol.

How Do Plant Sterols and Stanols Help?

On a molecular level, sterols and stanols look a lot like cholesterol. So when they travel through your digestive tract, they get in the way. They can prevent real cholesterol from being absorbed into your bloodstream. Instead of clogging up your arteries, the cholesterol just goes out with the waste.

“Plant stanol esters help block the absorption of cholesterol,” Frechman tells WebMD. “Research shows that three servings a day can reduce cholesterol by 20 points.”

Experts have been studying the effects of food fortified with plant sterols for decades. One important study of people with high cholesterol found that less than an ounce of stanol-fortified margarine a day could lower “bad” LDL cholesterol by 14%. The results were published in The New England Journal of Medicine.

A more recent study from the University of California Davis Medical Center looked at the effects of sterol-fortified orange juice. Of 72 adults, half received regular orange juice and half the fortified OJ. After just two weeks, the people who drank the stanol-fortified juice had a 12.4% drop in their LDL cholesterol levels. The results were published in the journal Arteriosclerosis, Thrombosis, and Vascular Biology.

The FDA gave these products the status of a “health claim.” This means that experts widely agree on the cholesterol-lowering benefits of stanols and sterols. It also allows manufacturers to advertise the heart-healthy benefits on labels.