FRIDAY, March 23 (HealthDay News) -- Although earlier studies had linked coffee to an increased risk for psoriasis, a large new study finds no such evidence.
Psoriasis is a common skin condition that causes skin redness and irritation. Most people with psoriasis have areas of thick, red skin with flaky, silver-white patches called scales.
"Our hypothesis was whether caffeine would lower the risk of psoriasis because there are hypotheses in the past that caffeine might be an anti-inflammatory," said lead author Dr. Abrar Qureshi, an assistant professor of dermatology at Harvard Medical School in Boston.
"However, we found there was no association between coffee intake and the risk of psoriasis," he said.
These findings agree with other studies that found no association between coffee and this skin condition, the researchers noted.
The reason that there has been an association of psoriasis with coffee may have to do with smoking and alcohol, which are known risk factors for psoriasis, Qureshi said. In the study, those who drank the most coffee also drank the most alcohol and smoked, he said.
"There have been reports that coffee increases the risk of psoriasis and that coffee helps quell psoriasis," he said. However, this study found no risk or benefit from coffee, Qureshi added.
The report was published in the March issue of the Archives of Dermatology.
For the study, Qureshi's team collected data on almost 83,000 women who took part in the Nurses' Health Study. In this large population, the researchers found no link between coffee or caffeine and developing psoriasis.
Dr. Doris Day, a dermatologist at Lenox Hill Hospital in New York City, said that this finding "makes perfect sense; it's what I would have suspected."
The real risk factor may be smoking, she said. "Smoking is toxic to every organ system and is especially toxic to the skin."
However, Day said that caffeine can be soothing to the skin and it is an ingredient in many skincare products, but it is not used for psoriasis, she said.
For more about psoriasis, visit the National Psoriasis Foundation.