Here’s some more (potentially) good news for coffee devotees: A new study finds that drinking four or more cups of coffee a day – a fairly hefty amount, by most counts – is linked to a reduced risk for melanoma, the most deadly form of skin cancer.
Melanoma is currently the fifth most common form of cancer in the U.S., and it’s the leading cause of skin cancer-related deaths. About 77,000 people are diagnosed with it each year, and 9,500 die of it each year. Though UV light – especially UVB rays – is the most powerful modifiable risk factor, there are other factors that raise or lower a person’s risk. The compounds in coffee have been shown to reduce skin cancer risk in lab studies, but in human studies, the results have been more variable, and the connection not so clear-cut.
To address the question in a large sample of people, researchers looked at data from over 447,000 participants, 50-71 years old, who were cancer-free at the beginning of the study. In the more than decade-long study period, just over 2,900 of the participants developed malignant melanoma, and over 1,900 developed another form of skin cancer, melanoma in situ. The researchers looked for correlations between diet and skin cancer development.
The found that among the most committed coffee drinkers – four cups a day – the risk of malignant melanoma fell by 20%. The connection applied only to caffeinated coffee and melanoma – it wasn’t there for decaffeinated coffee, or the other form of skin cancer included in the study, melanoma in-situ.
There are some good reasons that coffee may reduce skin cancer risk. In mice and in skin cell cultures, various components of coffee have been shown to affect a number of molecular pathways that can reduce risk for UV-related skin cancer. Among them, coffee compounds have been shown to suppress carcinogenesis (the formation of cancer), reduce inflammation, and reduce oxidative stress and DNA damage in cells.
Though the current study was a large one, the authors point out that previous studies have found less convincing results – one study found a link between coffee drinking and reduced skin cancer risk in women but not men. Another study found no connection to melanoma, but a connection to basal cell carcinoma. Other have provided similarly mixed results.
Still, given the biological pathways that coffee is known to affect, it’s very plausible that coffee may reduce risk of melanoma. But more research will be needed before we know for sure how the connection works. Coffee has been linked to a number of positive health effects – from reduced risk of death to reduced risk of certain cancers and diabetes to reduced risk of depression and Parkinson’s disease. Other studies, however, have found increased mortality in younger people who drink larger amounts of coffee; it’s studies like these that make researchers hesitant to give consumers the go-ahead to drink coffee ad libitum.
“The most important thing that individuals can do to reduce their risk of melanoma,” study author Erikka Loftfield tells me, “is to reduce sun and UV radiation exposure. While our results, and some from other recent studies, may be encouraging to coffee drinkers, they do not indicate that individuals should alter their coffee intake.”
There probably won’t ever be a definitive answer to the coffee question, because the answer probably varies from person to person. But the majority of research seems to say that for most people, coffee may do more good than harm. You probably shouldn’t pick up the habit if you’re not currently a coffee drinker, but if you’re already in the habit of a couple of cups a day, it probably won’t hurt, and in many ways, it may even help.
And for skin cancer risk, always wear sunscreen. That much, we do know.