Numerous plants contain cholesterol-like compounds called sitosterols and their close relatives sitosterolins. A special mixture of these called beta-sitosterol is used for the treatment of benign prostatic hyperplasia (BPH).

Some conditions are luckier than others. For some mysterious reason, there seem to be more useful herbal treatments for BPH than almost any other disease. Beta-sitosterol joins saw palmetto, pygeum, nettle, and grass pollen as a moderately well-documented treatment for BPH.

Based on highly preliminary evidence, it has been suggested that sitosterols may also help strengthen the immune system.2 In particular, one study suggests that beta-sitosterol can help prevent the temporary immune weakness that typically occurs during recovery from endurance exercise, and can lead to a post-race infection.3