Phytosterols are a group of molecules found in plants that serve a similar function in plants that sterols, such as cholesterol, serve in animals, which is primarily the stabilizing of cell membranes and the production of hormones. There are three primary phytosterols: beta-sitosterol, campesterol and stigmasterol. Phytosterols have been studied both as a group and individually to learn about their contributions to health and well-being as well as for their potential adverse effects.
Cardiovascular Disease
Diets supplemented with phytosterols inhibited absorption of cholesterol from food but did not reduce LDL cholesterol levels in the blood, according to a study published in the 2010 "European Journal of Clinical Nutrition." In the study, 24 participants divided into two groups ate two different diets for four weeks comprising only foods provided by the researchers. One of the experimental diets was low in phytosterols, with 126mg per 2000 calories, and the other was higher in phytosterols, with 449mg per 2000 calories. The higher phytosterol diet resulted in 20 percent lower cholesterol absorption and 79 percent higher cholesterol excretion. LDL cholesterol levels were similar for the two diets. The researchers concluded that phytosterols have considerable potential for use in managing cholesterol absorption from foods.
Prostate Cancer
A study on the comparison between the effects of cholesterol and phytosterols, including beta-sitosterol, on prostate cancer cells was published in 2010 in "Cancer and Epidemiology." The two types of molecules have similar chemical structures, enabling phytosterols to compete for absorption with cholesterol. However, opposite effects on cancer cells were observed for the two compounds in the study. Cholesterol had a growth-promoting effect on cancer cells, whereas phytosterols had a significant growth-suppression effect and also promoted apoptosis---programmed cell death---in the prostate cancer cells. The researchers predict that further research into the mechanism of action of phytosterols could result in a viable place for these compounds as a tool in the prevention and management of prostate cancer.
Osteoarthritis
A phytosterol known as stigmasterol was found to have potent anti-inflammatory properties in a study published in 2010 in "Osteoarthritis Cartilage." Cartilage cells from a patient with osteoarthritis were exposed to stigmasterol for 48 hours and then evaluated for various aspects of inflammation. The researchers noted that levels of collagen, a protein used in the production and repair of tendons and ligaments, were significantly reduced. Also, a gene that influences how cells respond to certain stresses was inhibited in stigmasterol-treated cells. The researchers conclude that stigmasterol was effective at lowering inflammation and cellular breakdown associated with osteoarthritis in several different ways and note that this study offers encouraging results for the future of phytosterols in the prevention and management of osteoarthritis.
References
- PubMed: Stigmasterol: A Phytosterol With Potential Anti-Osteoarthritic Properties
- PubMed: Cholesterol and Phytosterols Differentially Regulate the Expression of Caveolin 1 and a Downstream Prostate Cell Growth-Suppressor Gene
- PubMed: The Effects of Phytosterols Present in Natural Food Matrices on Cholesterol Metabolism and LDL Cholesterol
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