Wednesday, May 14, 2014
Recent reports that “red wine is not great for health after all” and that “no amount of alcohol is safe” are just plain wrong. This type of misguided reporting and misinterpretation of scientific studies is one of the reasons for my book Age Gets Better with Wine. How is it that the story is still so confused?
Kicking off the latest round of hype was a report issued bythe World Health Organization’s International Agency for Research on Cancer. Noting that the risk is dose-dependent, meaning that heavy drinking has a stronger correlation with some types of cancer, the authors of the report concluded that even moderate drinking carries some degree of risk. This was followed by release of a study in Italy that looked at dietary levels of resveratrol and incidence of diseases of aging. Since the most well-known source of resveratrol is red wine, the lack of a benefit from higher resveratrol consumption was reported as casting doubt on the benefits of red wine.
So here we go again: It is well-documented that people who consume red wine in moderation, on a daily basis, live longer, have lower rates of cancer and other diseases of aging, and have better mental function and higher quality of life as compared to nondrinkers. They are also healthier than heavy drinkers, so the relationship of wine consumption and disease risk is not a linear dose-response but a J-shaped curve. One reason why this is not recognized is what is called “self-reporting bias,” which means that heavy drinkers tend to under-report their true consumption and so are categorized as moderate drinkers. Another reason is that there are comparatively few true consumers of red wine in moderation and they are hard to isolate statistically. Most people tend to drink in more erratic patterns as compared to the more traditional habitual glass of wine with dinner. These types of things confound data but lumping this group in with all drinkers and declaring alcohol a carcinogen is sloppy science and wrongheaded.
The bigger problem with this report is that it looks only at cancer risk, not overall health and longevity. Even if we ignored the evidence that moderate wine drinkers actually have lower cancer risk and assumed it was a linear dose-response relationship, the major cause of mortality is heart disease. Since moderate drinkers have a larger benefit of reduced heart disease risk than potential increase in cancer, the net result is still clearly positive. Add to that the benefits of wine on Alzheimer’s, diabetes, osteoporosis, etc. etc. and you will see my point.
But the big C is a scary thing, and a major point of emphasis in the report is breast cancer. The widely held view, based on the many studies that have been done, is that a drink a day increases risk of breast cancer by 10%; 2 drinks, 20% and so on. Lifetime risk of breast cancer is around 12%, but the risk of a daily drink (if any) would not increase risk to 22%, but rather 10% of the 12%, so the net is just over 13% - hardly measureable by statistical standards. Add to that the self-reporting bias and it is easy to see why alarmist reporting is unjustified. And as I have pointed out many times before, in populations where women drink primarily red wine, the incidence of breast cancer is substantially lower.
Which brings us to the question of whether red wine really is different. A study 783 elderly men in the Chianti region of Italy attemptedto answer this question by measuring resveratrol metabolites in the urine, and looking for a relationship of resveratrol to observed rates of cancer and longevity. The reasoning was that red wine’s benefits are due to resveratrol, which also occurs in other foods, so total resveratrol from all dietary sources should correlate to improved health. However, the study found no such correlation.
I could have told them that before they started the study, because there is not much resveratrol in any naturally occurring food including wine, so it was never the primary reason for red wine’s benefits. Remember the whole reason for doing the study was to try to find what it is about wine that would explain why wine drinkers fare so well; but it always comes back to just drinking the wine.