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What You Need to Know About Beta-Sitosterol


Updated July 02, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Beta-sitosterol is a substance found naturally in a number of foods, including soy, flaxseed, peanuts, olive oil, and many fruits and vegetables. Also available in dietary supplement form, beta-sitosterol is classified as a phytosterol (a class of compounds similar to cholesterol). Some scientific studies suggest that beta-sitosterol may offer certain health benefits.

Uses for Beta-Sitosterol

Beta-sitosterol is touted as a natural remedy for a variety of health conditions, including:

In addition, beta-sitosterol is purported to prevent heart disease and some forms of cancer (including prostate cancer and colon cancer). Proponents also suggest that beta-sitosterol can help stimulate the immune system, relieve pain, reduce inflammation, and enhance sexual function.

Benefits of Beta-Sitosterol

Here's a look at the science behind the potential health benefits of beta-sitosterol:

1) Benign Prostatic Hyperplasia

There's some evidence that beta-sitosterol may help treat benign prostatic hyperplasia (or BPH, a condition commonly referred to as "enlarged prostate"). Although BPH rarely causes symptoms in men under age 40, many older men experience BPH-related symptoms (including urination and bladder problems). BPH is not linked to increased risk for prostate cancer.

Beta-sitosterol appears to improve urological symptoms associated with BPH, according to a report published in BJU International in 1999. For the report, investigators analyzed four previously published clinical trials with a total of 519 men and a treatment period of four to 26 weeks. Although the report's authors concluded that short-term treatment with beta-sitosterol may help improve BPH symptoms, they caution that beta-sitosterol's effectiveness as a long-term BPH treatment is unknown.

There is a lack of more recent research on the effectiveness of beta-sitosterol in the treatment of BPH.

2) Cancer

Preliminary research suggests that beta-sitosterol may help fight colon cancer. In a 2010 laboratory study published in BMC Complementary and Alternative Medicine, for instance, scientists found that beta-sitosterol isolated from the Asclepias curassavica plant inhibited the growth of human colon cancer cells.

Some research indicates that beta-sitosterol may also fight breast cancer. For example, a 2003 laboratory study published in Oncology Reports found that beta-sitosterol induced apoptosis in breast cancer cells. Apoptosis, a type of programmed cell death, is key to halting the proliferation of cancer cells.

Furthermore, a 2008 laboratory study published in Molecular Nutrition and Food Research found that using beta-sitosterol in combination with the breast cancer drug tamoxifen may enhance the drug's effectiveness.

It's important to note that more research needs to be conducted before beta-sitosterol can be recommended for the treatment or prevention of any form of cancer.

Is Beta-Sitosterol Safe?

Beta-sitosterol is generally considered safe when consumed in recommended doses for up to six months. However, there's some concern that beta-sitosterol may contribute to harmful effects in people with certain chronic conditions (including diabetes, gallstones, and Alzheimer's disease). Therefore, it's critical to talk to your physician prior to using beta-sitosterol supplements.

Where to Find Beta-Sitosterol Supplements

Widely available for purchase online, beta-sitosterol supplements are sold in many natural-food stores and in stories specializing in dietary supplements.

Should You Use Beta-Sitosterol for Health Purposes?

Due to a lack of supporting research, beta-sitosterol cannot currently be recommended for treatment or prevention of any health problem. If you're considering the use of beta-sitosterol supplements, consult your doctor before starting your supplement regimen.

It's important to note that self-treating a chronic condition with beta-sitosterol and avoiding or delaying standard care may have serious health consequences.


Awad AB, Barta SL, Fink CS, Bradford PG. "beta-Sitosterol enhances tamoxifen effectiveness on breast cancer cells by affecting ceramide metabolism." Mol Nutr Food Res. 2008 Apr;52(4):419-26.

Awad AB, Chen YC, Fink CS, Hennessey T. "beta-Sitosterol inhibits HT-29 human colon cancer cell growth and alters membrane lipids." Anticancer Res. 1996 Sep-Oct;16(5A):2797-804.

Awad AB, Roy R, Fink CS. "Beta-sitosterol, a plant sterol, induces apoptosis and activates key caspases in MDA-MB-231 human breast cancer cells." Oncol Rep. 2003 Mar-Apr;10(2):497-500.

Baskar AA, Ignacimuthu S, Paulraj GM, Al Numair KS. "Chemopreventive potential of beta-Sitosterol in experimental colon cancer model--an in vitro and In vivo study." BMC Complement Altern Med. 2010 Jun 4;10:24.

Wilt TJ, MacDonald R, Ishani A. "beta-sitosterol for the treatment of benign prostatic hyperplasia: a systematic review." BJU Int. 1999 Jun;83(9):976-83.

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