This month’s newsletter is brimming with holiday cheer! In this, the final issue of 2006, we explore the health benefits of a compound in red wine called resveratrol. In case you needed another excuse to bring out the red wine this holiday season, read on!
But before you reach for your corkscrew, please remember to complete our brief online survey. We value your feedback about our organization and we welcome your comments. Remember, as a thank you, those who complete the survey will be entered to win one of two gift certificates to Barnes & Noble! The survey can be reached via the following link, and it will be available through January 5th 2007. <http://www.surveymonkey.com/s.asp?A=166137623E88305>
Best wishes for a healthy and happy new year!
--The SITN Staff
Have Your Cake and Eat It Too: Resveratrol to the Rescue?
Scientists and the general public alike have noted that the French have lower rates of obesity and heart disease than Americans do, despite the notorious richness of French food. There are probably many reasons for these health differences, but this so-called “French paradox” has led to the intriguing speculation that the French might be benefiting from their cultural love-affair with wine. In fact, for many years, scientific and epidemiological studies have suggested that moderate consumption of wine, especially red wine, may have health benefits, including protection against cancer, heart disease, and Alzheimer’s disease. As the evidence continues to accumulate, scientists around the world are investigating how red wine might confer these health benefits.
Scientists have extracted a number of interesting chemical compounds from red wine. Red wine, like green tea, dark chocolate, and pomegranates, among other foods and beverages, is particularly rich in substances called polyphenols. Polyphenols come in many varieties, including flavonoids and tannins, which are associated with a number of beneficial properties, including acting as antioxidants. Antioxidants, including vitamins C, A, and E, are compounds that protect cells against reactive oxygen species, commonly known as free radicals, which can wreck havoc on the body. One polyphenol compound which is particularly enriched in red wine is called resveratrol. Resveratrol has received a lot of attention lately for its intriguing properties, including its ability to prolong health and longevity in organisms such as worms, flies and fish. Most recently, an exciting study published in the prestigious journal, Nature, reported that resveratrol can offset the effects of a high-fat, high-calorie diet in mice.
In this study, the researchers, based out of Harvard Medical School, compared three groups of mice: one ate a normal diet, another began a high-fat, high-calorie diet in middle age, while the third ate a high-fat, high-calorie diet supplemented with resveratrol. The researchers found that the mice who consumed resveratrol lived many months longer than their counterparts who consumed the high-fat, high-calorie diet without resveratrol. Interestingly, while resveratrol did not prevent the mice from gaining weight on the high-fat, high-calorie diet, it did prevent many of the symptoms associated with obesity, such as the early signs of diabetes (including insulin resistance). The resveratrol treated mice also had fewer fat deposits in their livers and healthier hearts.
Obesity has been shown to be a risk factor for developing heart disease and diabetes, both potentially life-threatening, and certainly life-altering, diseases. One of the exciting implications of this study is that resveratrol may prevent some of the unhealthy consequences of being overweight. If this finding can be extended to humans, it is easy to imagine how taking supplemental resveratrol could benefit people who eat a high fat, high calorie diet—which unfortunately includes the majority of people in the U.S.
It is important to note that the dose of resveratrol used in this study was quite high -- 24 milligrams per kilogram of body weight per day. This is not a practical amount for a human to consume by wine consumption alone. As an illustration, a 150-lb person would need to drink approximately 1000 bottles of red wine each day to get that dose. It is, therefore, unlikely that resveratrol consumption via red wine alone can explain the “French paradox”. The most realistic explanation for the “French paradox” is in fact more complicated, encompassing multiple diet and lifestyle factors.
Exactly how resveratrol is able to counteract the effects of obesity in mice remains unclear. The antioxidant activity of resveratrol may account for some of its protective effects, as antioxidants have been associated with health for decades. However, resveratrol’s antioxidant properties are not the whole story. Resveratrol is also known to activate a protein called SIRT1. SIRT1, and proteins like it, are of great interest to scientists, because they are thought to be responsible for the increased longevity associated with calorie restriction. Studies dating back to the 1930’s have shown that restricting caloric intake by simply decreasing the amount of food consumed (while maintaining adequate nutrition) can extend the lifespan and improve the health of rats. Although a long healthy life is appealing to all of us, subsisting on a severely reduced calorie diet, is not. Therefore, there has been, and continues to be, great interest in determining how calorie restriction promotes health. SIRT1 and related proteins are emerging as key players.
Although resveratrol is known to activate SIRT1, it is still unclear if resveratrol produces its health benefits by directly and exclusively activating SIRT1 in living organisms, such as in the mice discussed above. To determine if the health benefits of resveratrol are dependent on SIRT1, scientists will need to show that resveratrol fails to counteract the effects of obesity in mice genetically-engineered to lack SIRT1. If resveratrol is shown to function via SIRT1, it would suggest that resveratrol converges on the mechanism implicated in calorie restriction, and that at least in some respects, resveratrol triggers mice to respond physiologically as if they were on a calorically restricted diet, even as they chowed down indulgently.
These findings are very exciting but it is still too early to say whether resveratrol will have equivalent health benefits in humans. It is possible that in the future doctors will recommend taking resveratrol as a supplement much like we take vitamins now. However, it is important to remember that even vitamins, safe and beneficial in small doses, can be harmful and toxic at higher doses. While supplements containing resveratrol are currently on the market, it is not yet clear whether they are safe and effective in humans. And while it is theoretically possible for humans to consume resveratrol in supplement form in equivalent amounts to those consumed by the mice in this study, the safety of high doses of resveratrol in humans is unknown, especially over extended periods of time. Additionally, as with most dietary supplements, resveratrol is not regulated by the U.S. Food and Drug Administration so the quality and purity of the merchandise is uncertain.
Although it is intriguing to imagine a pill capable of protecting us from the unhealthy consequences of obesity, scientists still have a long way to go in terms of unraveling the complexities of resveratrol. As the new year approaches, with its invitation for making resolutions, the wisest goals are still a healthy lifestyle, including sufficient exercise, healthy food (including lots of polyphenol-rich fruits and veggies) washed down, if you wish, with a glass of red wine.
-- Geng Li and Kelly Dakin, Harvard Medical School
For More Information:
Primary Research Article: Resveratrol improves health and survival of mice on a high-calorie diet. Nature. 2006 Nov 16;444(7117):337-42.
Harvard Focus magazine interviews the Harvard authors of the study which found the protective effects of resveratrol in mice <http://focus.hms.harvard.edu/2006/111006/pathology.shtml>
More details about resveratrol: <http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/res_0224.shtml>
More details about calorie restriction: <http://www.biologyofhumanaging.com/Topics/CR_nt.htm>
