MONTREAL — Women who drank alcohol, especially those who consumed at least five beers per week, were at increased risk of developing psoriasis, based on an analysis of the Nurses' Health Study.
Compared with abstainers, women who drank alcohol (defined as consumption of at least 30 g, or roughly two drinks, per week) had a significantly increased risk of developing psoriasis, with a relative risk (RR) of 1.59, said Dr. Patrick Dominguez, who presented his findings at the annual meeting of the Society for Investigative Dermatology.
When type of alcohol was examined, however, only regular beer consumption of more than five drinks per week was a significant predictor (RR 1.83) for the development of psoriasis. “For any amount of light beer, wine, or liquor consumed, the relative risks were not significant.”
At study entry in 1989, women in the Nurses' Health Study were asked about their level of alcohol consumption in grams per week. According to the Centers for Disease Control and Prevention, a standard drink contains 13.7 g of alcohol and is defined as 12 ounces of regular beer, 8 ounces of malt liquor, 5 ounces of wine, or 1.5 ounces of 80-proof distilled spirits.
Over a 14-year period, biennial questionnaires were used to monitor both the amount as well as the type of alcohol consumed (regular beer, light beer, wine, or liquor), said Dr. Dominguez, who is a research fellow in the department of dermatology at Brigham and Women's Hospital in Boston.
In 2005, participants were asked if they had psoriasis. A total of 2,169 reported a diagnosis of psoriasis; 1,162 were prevalent cases and the remaining 1,007 were incident cases, said Dr. Dominguez, who declared no conflicts of interest. After excluding incident cases for which there was incomplete information on alcohol consumption, 955 participants with new onset psoriasis were included for analysis.
The abstainers and women who drank alcohol did not differ significantly in age. Abstainers had slightly higher body mass indices. Drinkers were more physically active, and a higher percentage of drinkers also reported current or past smoking.
“We also measured dietary folate, which may be a modifier for alcohol's effect in psoriasis, and folate intake was higher in the drinkers, but not significantly higher,” Dr. Dominguez said.
One possible explanation for the study's findings is that gluten, a nonalcoholic ingredient found in beer, might trigger the onset of psoriasis, he speculated.
“There are multiple case series in which patients with gluten sensitivity, or celiac disease, and psoriasis go on a gluten-free diet, and their psoriasis clears up,” he said in an interview. “Beer is the only alcoholic drink that contains gluten. Light beer has some gluten but much less.”