May 12, 2005 -- A drink a day may do your kidneys more good than harm, rather than the other way around.
Although some previous studies show that alcohol use may be harmful to the kidneys and increase the risk of kidney failure, a large new study indicates that the reverse might be true -- at least when alcohol is consumed in moderation.
If those results hold up to further scrutiny, researchers say preventing kidney failure may be yet another benefit of drinking alcohol in moderation, in addition to other recently discovered perks, such as reducing the risk of heart disease and stroke. Moderation is defined as no more than two alcoholic drinks per day for men and one drink per day for women. A "standard drink" is defined as 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of 80-proof distilled spirits.
A New Benefit for Drinking in Moderation?
The study followed more than 11,000 healthy men for 14 years and found that men who averaged at least seven drinks per week had a 30% lower risk of having elevated blood creatinine levels, a marker of kidney dysfunction, compared with men who had one or fewer drinks per week.
A similar protective effect of moderate alcohol use was found for another marker of kidney health known as the glomerular filtration rate (GFR), which measures the normal filtering capacity of the kidneys.
The results appear in the May 9 issue of the Archives of Internal Medicine.
Researchers say the findings are contrary to previous studies that have shown alcohol use may increase the risk of kidney failure due to alcohol's effect on increasing blood pressure. Uncontrolled blood pressure is a risk factor for kidney failure.
While high blood pressure was more common in the group of men who drank moderate amounts of alcohol, this group had a decreased risk of kidney disease.
A similar, smaller study in women showed no protective effect of alcohol use on the risk of kidney dysfunction. Two other studies that examined the link between alcohol use and kidney health showed an increased risk of kidney dysfunction and kidney failure.
Researchers say one possible explanation for alcohol's protective effect on the kidneys may be due to its effect on so-called "good" HDL cholesterol levels. Men with the highest amounts of alcohol intake had the highest HDL cholesterol compared with men who never drank. A low HDL cholesterol level is also known to increase the risk of kidney dysfunction and eventual kidney failure.
Many of the heart-healthy benefits of moderate drinking have been attributed to its ability to increase HDL cholesterol levels.
But researchers are quick to point out that their study only looked at the effects of alcohol use on kidney function and didn't evaluate any of the other potentially harmful effects of alcohol use.