Beta-sitosterol is a plant sterol similar in structure to cholesterol, found naturally in fruits, vegetables, beans (especially soy), nuts, and seeds. Phytosterols, (plant sterols) including beta-sitosterol, contain a complex of specific types of plant sterols known as sitosterolins, stigmasterol and campesterol. Beta-sitosterol actually inhibits intestinal absorption of dietary cholesterol by competing for the limited space for cholesterol during intestinal uptake. It also affects an enzyme that results in the reduction of cholesterol rich lipoprotein, LDL. This can lower the LDL blood levels. Most of the early research focused on its use in lowering cholesterol in heart disease. Nowadays, it is also used for its ability to improve the symptoms related to benign prostatic hyperplasia (BPH), and several studies have been published to support its use for this.