In the past several months, scientific research papers have been stressing us out with puzzlingly contradictory findings on the benefits vs risks of moderate alcohol consumption. But don't worry about coffee. The delicious, life-giving brew continues to have our backs.
Adding to the long list of health perks associated with drinking coffee, a new study in JAMA Dermatology reports that women who regularly guzzled caffeinated coffee beverages were less likely to have rosacea – a frustratingly persistent and difficult-to-treat inflammatory facial skin condition characterized by redness, flushing, enlarged blood vessels, and texture changes. Overall, the more coffee consumed, the better the protective effect, but participants who drank four or more servings per day showed the strongest correlation: a 23 percent reduction in the odds of rosacea compared to those who drank coffee less than once per month.
The authors of the investigation, led by Wen-Qing Li at Brown University, drew their data from a large, well-known cohort study (the NHS II) that collected dietary, lifestyle, and medical information from tens of thousands of female nurses between the 1990s and early 2000s in order to examine risk factors for major diseases. Past research had implicated that caffeine and coffee might be a trigger for rosacea, but the evidence to date had been inconsistent and none had been derived from sizable cohort studies that differentiated coffee and decaf coffee from other drinks. Alcohol, spicy foods, sunlight, hairspray, makeup, and stress are some of the more common established causes.
Thankfully, in the NHS II food surveys – sent out every four years during the follow-up – subjects were questioned about their habitats regarding intake of coffee, tea, carbonated drinks, and chocolate. And in 2005, 82,737 of the women in the cohort had responded to a query asking if and when they had ever been formally diagnosed with rosacea.
For their statistical analysis of this ideal dataset, Li and his colleagues included each subjects’ self-reported caffeinated intake information collected between 1991 and either the end follow-up in June 2005 or the year when rosacea was diagnosed. To reduce the chance of confounders as much as possible, the team adjusted their calculations for the influence of smoking, alcohol intake, BMI, physical activity level – other factors with strong links to rosacea. To ensure they were only looking at cases where coffee intake could have an effect on rosacea, individuals diagnosed before four years of dietary history were established were excluded.
Caffeine from other beverages or chocolate were not associated with reduced rosacea, nor was decaf coffee. Thus, the authors speculate that the unique combination of caffeine and other bioactive compounds found in only coffee may counteract the symptoms of rosacea through vasoconstrictive and anti-inflammatory mechanisms, though this will need to be examined with future research.
In an editorial published alongside the study, University of Pennsylvania and University of California, San Francisco dermatologists Mackenzie Wehner and Eleni Linos explain that despite a few inherent limitations (such as the fact that it is all women, mostly Caucasians), Li’s results are compelling.
“This is an observational study, not a randomized clinical trial (RCT), widely considered to be the gold standard in evaluating causal relationships. However, a randomized trial of long-term coffee drinking would be difficult to carry out – recruiting to the control group would be problematic for sure. Without an RCT we must rely on large, prospective cohort studies like this one as the next best option in evaluating these relationships,” they write.
“This study provides evidence that patients with rosacea need not avoid coffee, and it offers all of us 1 more reason to continue drinking coffee regularly. We will raise an insulated travel mug to that!”