Numerous studies have found a link between drinking alcohol in moderation and living a longer life. The common interpretation is that the drink itself is behind the results, that either a balanced amount of alcohol or the polyphenols found in red wine provide health benefits.
But a new study asks whether it's the drinks or the person's medical history that's responsible. A team at the University of Texas found that past behavior versus current lifestyle decisions may help explain why moderate drinking is so beneficial later in life, compared to abstention or heavy drinking.
In research slated to be published in the November 2010 issue of Alcoholism: Clinical & Experimental Research, lead researcher Dr. Charles Holahan of the University of Texas at Austin and colleagues looked at outpatient data from 1,142 men and 682 women, aged 55 to 65 years, and followed them for 20 years, recording causes of death and other data. At the end they found that, compared to moderate drinkers, patients who abstained from alcohol had more than double the estimated mortality risk, while heavy drinkers and light drinkers had a 70 percent and a 23 percent higher mortality risk, respectively.
A large portion of the subjects who abstain from drinking admitted to prior problems with alcohol and/or poorer health habits. Lifetime moderate drinkers, they found, use alcohol less as a coping agent and more as a social lubricant. They also tend to exercise more often and had lower rates of obesity.
"Our findings are consistent with an interpretation that an important part of the survival effect for moderate drinking among older adults is explained by confounding factors associated with alcohol abstention," they say in the text. "Alcohol consumption of one or two drinks per day does not appear to increase the risk of cognitive impairment or decline in older adults."
But what of studies that find wine drinkers enjoy an extra benefit, presumably because of antioxidant compounds such as polyphenols found in red wine? The theory that polyphenols provide wine's benefits has led to a growing supplement industry, with shops selling resveratrol and other polyphenols in pill form.
A recent Dutch study looked at the chemical components found in grapes and found little to support claims that polyphenols such as resveratrol provide cardiovascular benefits when acting alone. "Grapes and wine contain high amounts of polyphenols, but the effects of these have hardly been investigated in isolation," write the researchers from Unilever Research and Development in the August issue of the Journal of Nutrition.
The research team examined 35 healthy males. The men ate low-fat diets and some took daily doses of capsules containing 800 mg of grape polyphenols. The others took a placebo.
Looking at blood flow, an indicator of heart health and overall longevity, the team found that the cardiovascular health of the men did not improve with either the antioxidant capsules or the substitute pills. The scientists write that the polyphenol treatment had "no major impact" on blood flow.
But they expressed doubt over whether their findings relate to wine drinking. "Please keep in mind that we tested only the effect of grape polyphenols provided as supplements," says lead author Linda A. J. van Mierlo. "Wine also contains other substances, such as alcohol."
It may be that the sum of components in wine is stronger than any part. But further research is needed on whether the answer is wine or lifestyle.