Benefits of Beta-Sitosterol
Beta-sitosterol is a plant sterol, a compound similar to cholesterol. It is not absorbed much from the digestive system to the rest of the body, so it works mostly within the digestive system. It works by blocking the absorption of cholesterol from the intestine. Cholesterol in the intestine comes from two sources: food and the liver. The liver secretes cholesterol into the intestines in the form of bile, and some of this cholesterol is reabsorbed back into the body. Because beta-sitosterol decreases the absorption of cholesterol in the intestine, it can decrease cholesterol levels in the body, even if you do not eat much cholesterol, because of the cholesterol from the liver.
Beta-sitosterol may work for an enlarged prostate by inhibiting an enzyme called 5-alpha-reductase, blocking the conversion of testosterone into DHT (dihydrotestosterone), thereby decreasing the amount of DHT in the body. Since DHT is important for enlargement of the prostate, this may be how beta-sitosterol works for BPH. In fact, several prescription prostate medications work in a similar way. Since these prescription medications are also effective for hair loss (particularly male pattern baldness), it is possible that beta-sitosterol may also work for hair loss, although no adequate research has shown this to be the case.
Beta-sitosterol is probably safe for children when consumed in small amounts, such as in foods. It is not known if it is safe in higher amounts. Since beta-sitosterol functional foods, like margarines or spreads with beta-sitosterol, are more expensive than their "regular" counterparts, and since there are no documented health benefits for such products in children, it is probably not worth the money to use these products in most children.