Beta-sitosterol is a type of chemical called a plant sterol. It's similar to cholesterol and is found in fruits, vegetables, nuts, and seeds.
Beta-sitosterol might help reduce cholesterol levels by limiting the amount of cholesterol that is able to enter the body. It can also help reduce swelling in the prostate and other tissues.
People most commonly use beta-sitosterol for lowering cholesterol levels and improving symptoms of an enlarged prostate (BPH). It's also used for heart disease, rheumatoid arthritis (RA), male-pattern baldness, and many other conditions.
In the US, foods that contain at least 650 mg of beta-sitosterol are allowed to state that they might reduce the risk for heart disease. Don't confuse beta-sitosterol with sitostanol, a similar plant substance.