Beta-sitosterol is one of several plant-derived sterols that is structurally similar to cholesterol. It is found in high concentrations in unrefined plant oils, seeds and nuts. It is also sold as a dietary supplement. It is thought that beta-sitosterol significantly inhibits cholesterol absorption in the gut, thereby reducing blood cholesterol levels. However, there is much debate over whether the effects of beta-sitosterol on cholesterol absorption produce clinically significant reductions in total blood cholesterol levels.
Cholesterol-Lowering
An analysis of 14 clinical studies in the May 2010 issue of the "Journal of the American Dietetic Association" reports that plant sterols do not significantly lower total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or triglyceride levels. A review of five studies in the May 2009 issue of "Diabetes Research and Clinical Practice" reports that plant sterols significantly reduced total and LDL cholesterol. A review of several studies in the October 2009 issue of the "Journal of the American College of Nutrition" concludes that plant sterols in combination with statin drugs lower total cholesterol and LDL levels. Overall the evidence is limited that beta-sitosterol lowers cholesterol levels in the general population, but its slight effects may be more apparent with combination therapies and in people with impaired lipid metabolism.
Benign Prostatic Hyperplasia
Benign prostatic hyperplasia is a condition that affects many men over the age of 50. It is characterized by symptoms of increased frequency and painful urination and is not considered precancerous. In a 2000 report from the "Cochrane Database of Systematic Reviews" the authors conclude from four different clinical trials that beta-sitosterols improve urinary symptoms and flow measures in men with benign prostatic hyperplasia.
Cancer
An article in the September 2000 issue of the "Journal of Nutrition" reports that beta-sitosterol and other plant-derived sterols may prevent certain cancers, such as those of the colon, prostrate and breast. The evidence for this conclusion is based on animal studies and laboratory experiments conducted in cancer cells. No studies as of December 2010 have confirmed the anticancer activities of beta-sitosterol in human populations.
References
- PubMed: The Comparative Efficacy of Plant Sterols and Stanols on Serum Lipids: A Systematic Review and Meta-Analysis
- PubMed: The Effect of Plant Sterols or Stanols on Lipid Parameters in Patients with Type 2 Diabetes: A Meta-Analysis
- PubMed: The Effect of Adding Plant Sterols or Stanols to Statin Therapy in Hypercholesterolemic Patients: Systematic Review and Meta-Analysis
- Beta-Sitosterols for Benign Prostatic Hyperplasia
- "Journal of Nutrition"; Phytosterols as Anticancer Dietary Components: Evidence and Mechanism of Action; Atif B. Awad and Carol S. Fink; September 2000
