Red wine, green tea and epidemiological paradoxes

As they’re scanning data on populations and health, epidemiologists sometimes happen upon an association that they identify as a “paradox.” A classic example is research in the 1970s on Greenlanders, who had a very high comsumption of fats–and yet, paradoxically, also showed low rates of heart disease.

A high-fat diet was generally associated with a high rate of heart disease elsewhere in the world, so why not in Greenland? The secret, it turns out, was that prominent among the fats consumed by Greenlanders were marine fats–fish oil, with its omega-3 fatty acids. (You’ve read about steadily increasing interest in the cardiovascular health benefits of omega-3 fatty acids in several postings on this blog.)

Then there’s the “French paradox.” Again, epidemiological studies pointed to a population with a rather high rate of saturated fat consumption (think cheeses, pate, sauces)–and yet the incidence of cardiovascular disease was not so elevated. Although many causes for this paradox have been set forth, probably the most popular explanation focused on red wine, a typical accompaniment to those high-fat French meals, and the source of a number of intriguing compounds, including one called resveratrol.

Resveratrol has attracted much research scrutiny over the years, and has been linked to multiple health benefits, including anti-cancer and anti-inflammatory effects, blood sugar lowering properties, and cardioprotective effects. Other research has focused on the ability of resveratrol to extend the life span of several short-living species of animals. Widely publicized investigations from just the last few years have looked to genetics to help explain how resveratrol might exert a life-extending effect similar to extremely low-calorie diets (we’re talking about near starvation)–but without the extreme caloric deprivation.

And here’s still another “paradox” being mulled over by the epidemiologists: the “Asian paradox.” In a 2006 study, investigators at Yale’s School of Medicine reviewed more than 100 studies on the health benefits of green tea, finding lower rates of heart disease and cancer in Asia despite high rates of cigarette smoking. Their theory? The average of 1.2 liters of green tea consumed by Asians each day would seem to provide high levels of polyphenols and other antioxidants. These compounds may improve cardiovascular health in several ways, including preventing blood platelets from sticking together and countering the oxidation of LDL cholesterol (the “bad” cholesterol)–which, in turn, can reduce the build-up of plaque in arteries.

All of the above sounds like excellent detective work on the part of the epidemiologists, but there are certain cautions. So much is now known about the cardioprotective properties of fish oil that both the American Heart Association and its European counterpart now include it as a standard recommendation for lowering cardiovascular risk. Yet it’s probably fair to say that scientists’ understanding of resveratrol and green tea is not so far along, and therefore the assertion of health benefits must be more provisional, awaiting further investigation and refinement. Still, it’s pretty clear that the researchers are onto at least something, so we’re grateful to those who first wondered at the meaning of epidemiological “paradoxes” such as these!

Fish oil, resveratrol, and green tea extract are all available as dietary supplements. For more information on how they are used, see the NYBC entries:

Resveratrol

Green Tea

Fatty Acids (includes Fish Oils – Max DHA from Jarrow and Pro Omega from Nordic Naturals).

You’ll find hundreds of articles on these supplements, but here are two recent references of special interest:

Barger JL, Kayo T, Vann JM, Arias EB, Wang J, et al. (2008) A Low Dose of Dietary Resveratrol Partially Mimics Caloric Restriction and Retards Aging Parameters in Mice. PLoS ONE 3(6): e2264. doi:10.1371/journal.pone.0002264

Sumpio BE, Cordova AC, Berke-Schlessel DW, Qin F, Chen QH. Green tea, the “Asian paradox,” and cardiovascular disease. Journal of the American College of Surgeons 202: 813-825 (May 2006)

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