May 14, 2009
Resveratrol is the compound behind red wines famous health benefits. And, despite its difficult pronunciation, consumers are finding this word on the tips of their tongues. There is definitely a growing awareness of the antioxidants found in grapes, says Matt Seale, sales and marketing, Muscadine Products Corporation, Wray, GA.
Although resveratrol was first isolated in 1940 from the roots of white hellebore, it piqued the interest of scientists when the health benefits of red wine came to light in the French Paradox, an observation that the French enjoyed lower rates of mortality from coronary heart disease despite their higher levels of saturated-fat intake and cigarette smoking.
Resveratrol, found in grapes, red wine, purple grape juice, peanuts and some berries, belongs to a class of polyphenolic compounds called stilbenes. Some plants produce resveratrol and other stilbenes in response to stress, injury, fungal infection or ultraviolet radiation. In grapes, resveratrol is only found in the skins, and the amount varies with the grape cultivar, its geographic origin and exposure to fungal infection. The amount of fermentation time a wine spends in touch with its skin also affects resveratrol content; thus, white and rosé wines contain less than red wines. Resveratrol appears to be well-absorbed when taken orally, but its bioavailability is relatively low due to its rapid metabolism and elimination.
Resveratrols disease fight
Exploring resveratrols potential health properties was a logical step, since both epidemiological and experimental studies had found a heart-health benefit with moderate red wine consumption. Laboratory experiments have since noted antioxidant, anti-inflammatory, anticancer, antiplatelet, cholesterol-lowering and mild estrogenic activities linked with resveratrol. Its important to note the lack of human research on resveratrol supplementation. Studies also suggest that even high dietary intakes of resveratrol may not result in human tissue levels high enough to see most of the protective effects demonstrated in cell-culture studies.
Ole Vagn, professor,University of Roskilde and scientific advisor to Fluxome Sciences A/S, Lyngby, Denmark, estimates dosage based on animal studies: Based on a single study on hamsters, an effect for humans will be observed using 1 gram resveratrol per day. Based on three rat studies, an effect for humans will be observed using 16 grams resveratrol per day. In a single mouse study, very high doses are used. One liter of red wine has on average 7 mg of trans-resveratrol.
Is resveratrol responsible for the heart-health benefits found in wine? It is too early to know for sure, but scientists have found that resveratrol effectively neutralizes free radicals and other oxidants and inhibits low-density lipoprotein oxidation in the test tube. It is a well-accepted theory that oxidative stress caused by free radicals plays a crucial role in the development of atherosclerosis. In addition, resveratrol appears to possess a range of other properties, including inhibition of platelet aggregation, antiarrhythmic and vasorelaxation actions, and inhibition of apoptotic cell death that protects from myocardial ischemic reperfusion injury, atherosclerosis and ventricular arrhythmias. More research needs to occur to fully understand the relationship between resveratrol and heart health. Resveratrol may offer protection against cancer. As a possible anticancer agent, it has been shown to inhibit or retard growth of various cancer cells in culture and implanted tumors in vivo. It also inhibits experimental tumorigenesis in a wide range of animal models. The National Cancer Institute, Bethesda, MD, reports that resveratrol exhibits activities in three major steps of carcinogenesis: anti-initiation activity, anti-promotion activity and anti-progression activity. A clinical trial exploring its effects on colon cancer patients is currently underway.
Another interesting area of research involves longevity. Dietary supplementation with resveratrol may produce effects similar to calorie restriction on metabolism and longevity in mice. In mice made obese with a high-fat diet, resveratrol provided an average of 15% longer lifespan compared with those that did not receive the supplement. Resveratrol also promoted an extension in the lifespan of yeast, worms, fruit flies and a vertebrate fish. Resveratrols effects on longevity in higher animals needs to be investigated to gain more knowledge in this area.
The wine pill
Resveratrol supplements, in doses of 10 to 50 mg, have grown popular among consumers. Most U.S. resveratrol supplements come from extracts of the root of Polygonum cuspidatum. Grape and wine extracts containing resveratrol and other polyphenols are also attracting attention. Seale notes the value of grape skin and seeds that were once discarded as compost in the vineyard. These grape extracts would be ideal to fortify a juice beverage with an antioxidant boost, he says. It could also be used in combination with other juices, such as blueberry, that can be tart. Resveratrol and grape supplements have particular appeal among teetotalers; they can enjoy the benefits of red wine sans alcohol. Trans-resveratrol is an antioxidant, so will by nature oxidize with the presence of air. In general, the matrix where trans-resveratrol is added will, to some extent, protect it from oxidation, says Sami Sassi, product manager, Fluxome. Whether the production or process will affect oxidation, much depends on the application itself... Granulation and microencapsulation together with premixes with other antioxidants can be applied, if required by the customer. Scientists are just scratching the surface in this field of research, but the future looks rosy for resveratrol.
Sharon Palmer is a registered dietitian with 16 years of experience in health-care and foodservice management. She writes on food and nutrition for newspapers, magazines, websites and books. Palmer makes her home in Southern California and can be reached at [email protected].
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