Beta-sitosterol alone and in combination with similar plant sterols reduces blood levels of cholesterol.1 2 3 This appears to be because beta-sitosterol blocks absorption of cholesterol.4 It has also been effective in reducing symptoms of benign prostatic hyperplasia.5
Although molecules quite similar to beta-sitosterol inhibit cancer cells in test tubes, the relevance of this information for people remains unknown.6
Where is it found? Beta-sitosterol is one of several plant sterols (cholesterol is the main animal sterol) found in almost all plants. High levels are found in rice bran, wheat germ, corn oils, and soybeans. Peanuts and its products, such as peanut oil, peanut butter, and peanut flour, are good sources of plant sterols, particularly beta-sitosterol.7
Who is likely to be deficient? Because beta-sitosterol is not an essential nutrient, deficiencies do not occur.
How much is usually taken? Between 500 mg and 10 grams of beta-sitosterol per day have been used in clinical research to reduce elevated blood cholesterol levels. Between 60 (20 mg three times per day) and 130 mg per day have been used in trials reporting a reduction in prostatic hyperplasia-related symptoms.8 9
Are there any side effects or interactions? No significant side effects or interactions have yet been reported in studies on beta-sitosterol.
At the time of writing, there were no well-known drug interactions with beta-sitosterol.
1. Lees AM, Mok HYI, Lee RS, et al. Plant sterols as cholesterol-lowering agents: clinical trials in patients with hypercholesterolemia and studies of sterol balance. Atherosclerosis 1977;28:325�38.
2. Pelletier X, Belbraouet S, Mirabel D, et al. A diet moderately enriched in phytosterols lowers plasma cholesterol concentrations in normocholesterolemic humans. Ann Nutr Metab 1995;39:291�5.
3. Jones PJ, Raeini-Sarjaz M, Ntanios FY, et al. Modulation of plasma lipid levels and cholesterol kinetics by phytosterol versus phytostanol esters. J Lipid Res 2000;41:697�705.
4. Grundy SM, Ahrens EH Jr, Davignon J. The interaction of cholesterol absorption and cholesterol synthesis in man. J Lipid Res 1969;10:304�15 [review].
5. Berges RR, Windeler J, Trampisch HJ, et al. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Lancet 1995;345:1529�32.
6. Kiriakdis S, Stathi S, Jha HC, et al. Fatty acid esters of sitosterol 3�-glucoside from soybeans and tempeh (fermented soybeans) as antiproliferative substances. J Clin Biochem Nutr 1997;22:139�47.
7. Awad AB, Chan KC, Downie AC, Fink CS. Peanuts as a source of �-sitosterol, a sterol with anticancer properties. Nutr Cancer 2000;36:238�41.
8. Berges RR, Windeler J, Trampisch HJ, et al. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Lancet 1995;345:1529�32.
9. Klippel KF, Hiltl DM, Schipp B. A multicentric, placebo-controlled, double-blind clinical trial of �-sitosterol (phytosterol) for the treatment of benign prostatic hyperplasia. Br J Urol 1997;80:427�32.