Beta-sitosterol is one of a group of organic compounds found in plants that, alone and in combination with similar plant sterols, reduces blood levels of cholesterol.

The reduction of cholesterol levels appears to be because beta-sitosterol blocks absorption of cholesterol. It has also been effective in reducing symptoms of benign prostatic hyperplasia. Although molecules quite similar to beta-sitosterol inhibit cancer cells in test tubes, the relevance of this information for people remains unknown.