Wine Absent From Health Conference

December 2011
by Andrew Waterhouse
At this year’s fifth International Conference on Polyphenols and Health in Sitges, Spain, the words “antioxidant” and “wine” were hardly mentioned by the 700 participants from 47 different countries. This modern resurgence of interest in polyphenols was launched by the antioxidant hypothesis from the University of California, Davis, which proposed to explain the French Paradox, how wine could prevent cardiovascular disease, back in 1993. But today’s cutting-edge work has moved beyond the general concept of antioxidants, now finding exactly which biological pathways are affected, and instead of wine, the foods studied are olive oil, tea, juice and supplements, among others.

At the first meeting in Vichy, France, back in 2003, wine-related talks comprised a major part of the meeting, including talks addressing the epidemiology of wine, the chemistry and in-vitro and animal studies. But this year only one speaker addressed wine as a subject of the research, and among the 550 posters, less than 10 mentioned wine. It appears that in both Europe, where most of the research is conducted, as well as in the United States, there is very little new work on wine.

This is no accident. Since about 2000, the U.S. wine industry has pursued a policy of not funding health-related research, and the U.S. government has always avoided supporting any research that might show benefits to alcohol consumption. Europe seems to be adopting a similar approach. On the other hand, there were many talks addressing olive oil, chocolate and juices including grape juice, with strong industry funding in all these commodities. Welch’s funded a major and very impressive investigation into the metabolic fate of the phenolics of grape juice that is certain to inspire other scientists to proceed with confidence in studying the more applied health implications of grape juice.

Some very interesting reports included data showing that phenolics affect the metabolism of other nutrients and may reduce the tendency toward obesity. In today’s public health situation, this could be of great interest. It appears that other foods in the diet can affect how we digest phenolics. One study showed that human test subjects had more phenolics in their urine when consuming tomatoes with olive oil than without.

One aspect of the meeting that some may not find appealing was the prevalence of studies of these compounds in both urine and feces. Bacteria in the human gut turns out to be the major factor in digestion of polyphenols. The current rough estimates are that the phenolics we absorb into our blood arise 50%-90% in the colon, and not from direct absorption in the ileum. These molecules are highly transformed by colonic bacteria so that in the past these products were totally overlooked. There were many reports starting with an overview of how these bacteria are counted and categorized (new-generation total genomics analysis) to the effect of phenol consumption on gut microflora and, of course, how different bacteria can alter those phenols.

While wine-specific studies were nearly absent, the studies of phenolics that occur in wine still have some application to wine and grape consumers. The one wine-specific study presented orally was by Joseph Kanner, one of the antioxidant hypothesis authors. He showed that consumption of wine polyphenols when eating meat results in lower lipid oxidation in the stomach and lower levels of toxic aldehydes circulating in blood—a good reason to drink red wine with red meat!

A study of colonic polyps (precursors to colon cancer) showed that a grape seed preparation reduced the size and number of polyps in mice, and a separate study of grape seed extract showed sound biological mechanisms to explain its blood pressure-lowering effect. Overall, a useful understanding of the health impact of phenolics is now emerging.

Upon leaving the beautiful seaside Sitges, I was disappointed that a field of investigation launched by a wine study is now passing it by, by design. I wonder if the absence of such work will affect the public’s perception of the health benefits of wine. Epidemiology continues to show an association between wine consumption and better health, but without mechanistic explanations for the associations, a causal link cannot be drawn.

The next conference will be held in Buenos Aires during 2013, and for me the question is whether or not wine will be mentioned at all. The conference organizers want to encourage scientists from expanding South America to learn more about polyphenols, and of course to become regular attendees to this meeting, adding one more continent (four in all) to the scope of the conference. Perhaps the winemakers in Mendoza will support some health-related studies in anticipation of this meeting.

Dr. Andrew Waterhouse is a professor of enology at the University of California, Davis, leading studies of wine chemistry including phenolics and health. He is currently on sabbatical leave to learn about metabolomic analysis at Foundation Edmund Mach in all’Adige, Italy.

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