Polyphenols are a category of naturally-occurring compounds in plants, some of which are believed to have beneficial effects on health. Polyphenols act as antioxidants and may be useful in prevention of certain diseases, notably heart disease and some forms of cancer. Check with your doctor before using polyphenols to treat a medical condition.
Cocoa
Polyphenols in cocoa lowered cholesterol levels in high-risk participants of a study conducted at the Nutrition and Food Science Department of the University of Barcelona. Volunteers, average age 70, consumed 40 g of cocoa powder with 500 mL of skimmed milk each day for four weeks. Levels of high density lipoprotein, or HDL, the "good" form of cholesterol, increased by 2.67 mg/dL and oxidized low density lipoprotein, or LDL, the "bad" form of cholesterol decreased by 12 mg/dL. Researchers concluded that their study demonstrated a beneficial effect of cocoa polyphenols on cholesterol and lipid metabolism. The study was published in the May 2011 issue of the journal "Nutrition, Metabolism and Cardiovascular Diseases."
Atherosclerosis
Researchers at the Department of Food Science, Graduate School of Nutrition and Biosciences, The University of Tokushima, in a review of previously published research, noted that polyphenols suppress atherosclerotic plaque formation by decreasing white blood cell activity and inhibiting transport of oxidized LDL into white blood cells in the linings of arteries, processes that are associated with the beginning stages of atherosclerosis. Quercitin, a type of polyphenol, has also been shown to inhibit oxidaton of LDL cholesterol. The review study was published in the April 2011 issue of the journal "Bioscience, Biotechnology and Biochemistry."
Smokers
Resveratrol, a polyphenol antioxidant in red wine, may protect heart function but not blood vessel function in smokers, according to a study by the Toxicology Graduate Program of the University of Saskatchewan, Canada. In the laboratory animal study, 5 mg/kg body weight of resveratrol per day for 14 days increased strength of the left ventricle -- the heart chamber that pumps blood out to the body. However, it did not improve arterial blood flow, C-reactive protein -- a measure of inflammation -- or elevated white blood cell count, all signs of dysfunction in blood vessels. The study was published in the April 2011 issue of the journal "Food and Chemical Toxicology."
Questionable Effects
A study by scientists at the RIKILT-Institute of Food Safety and Division of Human Nutrition, Wageningen University, The Netherlands brought into question the antioxidant effects of polyphenol compounds in cardiovascular health. Polyphenol levels in your blood tend to be lower than levels of other antioxidants. Additionally, polyphenols undergo a lot of structural changes during the digestive process that lower their antioxidant activity. The researchers of the study, published in the May 2011 issue of the "Journal of Nutrition," concluded that, although cardiovascular benefits of polyphenols have been observed, they are not due to direct antioxidant activity of polyphenols.
References
- "Nutrition, Metabolism and Cardiovascular Disease"; Regular Consumption of Cocoa Powder with Milk Increases Hdl Cholesterol and Reduces Oxidized Ldl Levels in Subjects at High-risk of Cardiovascular Disease; N. Khan, et al.; May 2011
- "Bioscience, Biotechnology and Biochemistry"; Immunochemical Detection of Food -Derived Polyphenols in the Aorta"; Yoshichika Kawai; April 2011
- "Food and Chemical Toxicology"; Resveratrol Preserves Cardiac Function, but Does Not Prevent Endothelial Dysfunction or Pulmonary Inflammation After Environmental Tobacco Smoke Exposure; A.N. Al-dissi, et al.; April 2011
- "Journal of Nutrition"; The Biological Relevance of Direct Antioxidant Effects of Polyphenols for Cardiovascular Health in Humans is Not Established; P.C. Hollman, et al.; May 2011
- TheFreeDictionary.com: Polyphenols
