Campesterol is a phytochemical that is structurally similar to cholesterol. It is a type of sterol, known as a phytosterol, that is produced by plants. This type of compound inhibits the absorption of cholesterol in the intestines. Campesterol is one of the plant sterols that is added to foods to improve their ability to lower levels of total and LDL or ‘bad’ cholesterol.
There are over 40 phytosterols identified so far, with the most prominent being campesterol, beta sitosterol, and stigmasterol. These compounds are present in a variety of plant-based foods, often at low levels. Corn and canola oil have relatively high levels of campesterol.
The functions of phytosterols in plants are similar to that of cholesterol in animals. Their primary function is to help to stabilize the plants’ membranes. In humans, they are metabolized in a manner similar to cholesterol. Some of the cholesterol in the blood is bound to HDL or ‘good’ cholesterol and taken to the liver, where it is secreted into bile and removed from the system. Some of this can end up recycled back into the bloodstream.
When a plant sterol, such as campesterol, is present, it can compete with the cholesterol processing in the liver and end up being transported into the bloodstream instead of cholesterol. This can have the effect of lowering cholesterol levels. The presence of phytosterols in the blood appears to be beneficial and is thought to reduce the chance of developing cardiovascular disease.
Manufacturers started adding phytosterols to foods, like margarines, in the late 1990s. In addition to the plant sterols themselves, there are derivatives known as esters. Such compounds have a fatty acid linked to the sterol by an ester linkage. Another class of derivatives of phytosterols is stanols, in which the double-bond has been eliminated by the addition of hydrogen. Both plant sterols and stanols are added to foods to enhance their appeal to the health conscious.
It is thought that our ancestors ate large amounts of phytosterols. The typical Western diet is woefully deficient in them, however. The consumption of additional phytosterols and its derivatives in the diet can lower total and LDL cholesterol levels. The Food and Drug Administration (FDA) of the United States has allowed such functional foods to claim that they have cholesterol-lowering abilities when eaten as part of a heart-healthy diet.
There is some concern that, as phytosterols block the absorption of cholesterol, they may also block the absorption of additional important nutrients. For this reason, it may be wise to limit the intake of foods with enhanced phytosterols to those with elevated levels of cholesterol. Women who are pregnant or breastfeeding are advised against supplementing their diet with phytosterols, such as campesterol.