Women who drink five or more regular beers a week are at a higher risk for developing psoriasis, researchers said.
But women who drink similar quantities of wine, liquor and light beer do not appear to be any more susceptible than nondrinkers, suggesting something unique to regular beer, such as high levels of gluten, might be to blame, according to Dr. Abrar A. Qureshi of Brigham and Women's Hospital in Boston and colleagues.
Among more than 100,000 women studied from 1991 to 2005, the risk for developing psoriasis was 76 percent higher for those who reported drinking at least five non-light beers per week compared with nondrinkers, the researchers reported online in Archives of Dermatology.
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The researchers adjusted for a variety of other risk factors, including age, obesity, smoking, physical activity and dietary patterns. Drinking habits were assessed at the start of the study, and were compared with subsequent development of psoriasis during follow-up.
Based on the observation that drinking was generally a risk factor for psoriasis, the researchers went on to determine whether certain types of alcohol were associated with a greater risk. There was no increase in risk linked to red wine, white wine, liquor or light beer in any quantity.
The results were based on participants' self-reports of a physician diagnosis of psoriasis. When the analysis was restricted to psoriasis cases confirmed with the Psoriasis Screening Tool, the association was even stronger.
The researchers could not rule out the possibility that these associations were a statistical aberration, but they pointed out that gluten protein has previously been associated with psoriasis risk.
"Beer is one of the few nondistilled alcoholic beverages that use a starch source for fermentation, which is commonly barley," Qureshi and colleagues wrote.
"Starch sources such as barley contain gluten, which has been shown to be associated with psoriasis," they noted, citing a study showing that psoriasis patients had high titers of antibodies that might reflect a "latent-gluten sensitivity."
Light beer also contains gluten, but its brewing uses smaller quantities of grain compared with regular beer, the researchers noted.
"It remains unknown whether gluten contributes to new-onset psoriasis," Qureshi and colleagues reported.
Nonetheless, they suggested that women with other risk factors for psoriasis might do well to avoid drinking more than the occasional regular beer.