Plant sterol

Phytosterols, which encompass plant sterols and stanols, are phytosteroids, similar to cholesterol, which occur in plants and vary only in carbon side chains and/or presence or absence of a double bond. Stanols are saturated sterols, having no double bonds in the sterol ring structure. More than 200 sterols and related compounds have been identified. Free phytosterols extracted from oils are insoluble in water, relatively insoluble in oil, and soluble in alcohols.

Phytosterol-enriched foods and dietary supplements have been marketed for decades. Despite well documented LDL cholesterol lowering effects, no scientifically proven evidence of any beneficial effect on cardiovascular disease (CVD) or overall mortality exists.

The molecule on the left is β-sitosterol. Nomenclature for steroid skeleton is on the right.

The richest naturally occurring sources of phytosterols are vegetable oils and products made from them. Sterols can be present in the free form and as fatty acid esters and glycolipids. The bound form is usually hydrolyzed in the small intestines by pancreatic enzymes. Some of the sterols are removed during the deodorization step of refining oils and fats, without, however, changing their relative composition. Sterols are therefore a useful tool in checking authenticity.

As common sources of phytosterols, vegetable oils have been developed as margarine products highlighting phytosterol content. Cereal products, vegetables, fruit and berries, which are not as rich in phytosterols, may also be significant sources of phytosterols due to their higher intakes.

The intake of naturally occurring phytosterols ranges between ~200-300 mg/day depending on eating habits. Specially designed vegetarian experimental diets have been produced yielding upwards of 700 mg/day. The most commonly occurring phytosterols in the human diet are β-sitosterol, campesterol and stigmasterol, which account for about 65%, 30% and 3% of diet contents, respectively. The most common plant stanols in the human diet are sitostanol and campestanol, which combined make up about 5% of dietary phytosterol.

...
Wikipedia