Monday, November 22, 2010

Hope for wine allergy sufferers

It seems at every talk I give on wine’s contribution to healthy living, there is at least one person in the audience who asks about wine allergies. Maybe they can’t drink red (thereby missing out on a lot of the antioxidant polyphenols), or maybe not wine at all. Sulfites are often blamed, but they are naturally present in all wines, beyond what is commonly added for preservation, and actual sulfite allergies are comparatively rare. What’s more, sulfites are higher in white wine, while allergic reactions are more common to reds. The question of why so many people have reactions to wine has remained largely unanswered until now.

A study from the Department of Biochemistry and Molecular Biology, University of Southern Denmark, and the Agricultural Research Council, Research Unit for Table Grapes and Wine Growing in Turi, Italy has identified a class of molecules called glycoproteins as the culprit. These are ubiquitous biological compounds that are comprised of a sugar portion (glyco-) attached to a protein. Examples include several hormones, connective tissue structures, and even antibodies. These molecules are commonly ensconced in the cell membrane, where they may help to identify what type of cell they are part of. Immune surveillance can be very tuned in to these molecules and so they are fairly common allergens. The Danish-Italian study identified some 28 different glycoproteins in wine with similarities to known plant allergens.

Unfortunately, glycoproteins in wine are derived from the grapes themselves as well as the yeast required for fermentation. It is possible that different strains of yeast might explain the differences in reactions to different wines (for example, people who are able to drink European wines but not the same varietal from a domestic producer), but using different yeasts would change the character of the wine. But this isn’t to say that nothing can be done. Hopefully some clever winemaker will target the market segment of those who would like to drink wine but can’t, and figure out some fining method or other means to remove glycoproteins from wine without sacrificing character. Clearly there is a lot more to learn about glycoproteins and wine allergy, but at least we now have something to go on.

Palmisano G, Antonacci D, Larsen MR. Glycoproteinomic profile in wine: A sweet molecular renaissance. J Protenome Res 2010 Oct 1; [epub ahead of print]

Friday, November 12, 2010

Madeira for malaria?

Of all of the scourges of mankind, malaria ranks near the top of the list, affecting more people worldwide that the entire population of the U.S. It has been notoriously resistant to vaccines, in part because of the complex life cycle of the parasite, which spends part of its development in the mosquito and part inside the red blood cells of people. It is this latter part that raises an interesting possibility for treatment with the red wine compound resveratrol, as reported at a recent meeting of tropical medicine specialists.

You may be familiar with the antibiotic properties of resveratrol and other polyphenol molecules from red wine. These compounds come from the skins, where the grapes form them as part of their natural environmental defense. Plants, and especially ripening fruit, are vulnerable to bacteria, viruses and fungus just as animal are, and this explains the broad spectrum of antibiotic capabilities of resveratrol. Wine’s use as a means of purifying drinking water over the past few thousand years is likely based as much on this as its alcohol content. Parasites such as the malaria bug are more difficult to suppress, and so the activity of resveratrol was unexpected.

One reason for this is that resveratrol’s inhibition of malaria works indirectly, by altering the red blood cells that contain the bug. In order for the more sever manifestations of malaria to occur, the blood cells need to adhere to the lining of the blood vessels, which resveratrol prevents (this is actually related to how it helps prevent heart attacks). So the idea isn’t that resveratrol can eradicate the parasite, but rather to mitigate the more severe effects of it while treating with anti-malarial drugs.

Since malaria is most common in tropical climates and developing countries, any effect of wine consumption would be a difficult association to discover. The British, during the Raj turned to quinine and the now-classic gin & tonic rather than claret for the same practical reasons. It is a bit difficult to picture fine Bordeaux becoming the standard prophylaxis in sub-Saharan Africa, but it may well hold the key to minimizing a lot of suffering.