A big research revealed Wednesday discovered a stunning hyperlink between fish consumption and growing melanoma, probably the most severe sort of pores and skin most cancers. But whereas the discovering raises questions on attainable hyperlinks between weight-reduction plan and melanoma, the research’s lead creator and different specialists cautioned that it’s not a cause to keep away from consuming fish. It additionally doesn’t change a very powerful recommendation for lowering melanoma threat: Limit your exposure to UV rays from the solar or tanning beds.
The new research, published in the journal Cancer Causes & Control, evaluated knowledge from greater than 490,000 adults within the United States between the ages of fifty and 71 who have been enrolled within the N.I.H.-A.A.R.P. Diet and Health Study. At the beginning of the research, members accomplished detailed questionnaires, together with details about their fish consumption, after which have been adopted for about 15 years to trace most cancers diagnoses among the many group. Compared with those that ate hardly any fish, the group that ate probably the most — on common 10 ounces, or about three servings, per week — had 22 p.c extra circumstances of malignant melanoma, the researchers discovered.
It’s not clear why consuming fish would possibly have an effect on an individual’s threat of growing melanoma, stated Eunyoung Cho, an affiliate professor of dermatology at Brown University and the lead creator of the research. “We believe it’s not fish per se, but probably some contaminant in fish,” she stated. Other research have discovered that individuals who eat extra fish have larger ranges of heavy metals resembling mercury and arsenic within the physique. These similar contaminants are additionally related to a higher risk of skin cancer, she famous. However, her research didn’t measure contaminant ranges in members, and extra analysis is required to discover this hyperlink, she stated.
“I wouldn’t discourage people from having fish just because of our finding,” Dr. Cho stated. Eating fish is related to a decrease threat of heart problems and possibly even another cancers, she identified. The American Cancer Society recommends selecting fish, poultry and beans extra usually than pink meat, and the American Heart Association advises consuming two servings of fish per week for coronary heart well being. (One serving is three ounces of cooked fish, in line with the A.H.A., or about three-quarters of a cup of flaked fish.)
Other specialists have been equally cautious of their interpretation of the research’s findings. “This does not change dietary recommendations for fish intake as part of a heart-healthy, anti-inflammatory or broad cancer prevention diet,” Carrie Daniel-MacDougall, an affiliate professor of epidemiology on the University of Texas MD Anderson Cancer Center, wrote in an e-mail.
Dr. Daniel-MacDougall led an earlier evaluation, with a shorter follow-up time and fewer variables, of the identical N.I.H.-A.A.R.P. cohort included in the newest research. Her paper, published in 2011, additionally discovered a correlation between fish consumption and melanoma threat. However, the N.I.H.-A.A.R.P. research was initially designed to trace many kinds of cancers, and it didn’t measure necessary and well-known melanoma threat elements, like a historical past of sunburns or higher lifetime UV publicity, Dr. Daniel-MacDougall wrote. People with these threat elements could have spent extra time within the solar — maybe on the seaside or fishing — and should have additionally been extra more likely to take pleasure in seafood, she identified. Without extra data, it’s unimaginable to find out if it’s the fish, time within the solar or another issue driving the higher melanoma threat.
Dr. Sancy Leachman, director of the Melanoma Research Program at Oregon Health & Science University, stated the brand new research was well-designed and referred to as the findings “intriguing.” But, she stated, when “you crunch large data sets like this,” what you discover are correlations between elements, not proof that one causes one other. This sort of research is sweet for growing new hypotheses — that contaminants present in fish would possibly enhance the danger of melanoma, for instance — however they want rather more analysis to see in the event that they maintain up.
“Science evolves, and you can’t do everything overnight. That’s just part of the process,” Dr. Leachman stated.
Many research have recognized correlations between certain foods and types of cancer, however basically, when extra research are carried out and the outcomes are checked out as an entire, the results usually turn out to be smaller or disappear altogether. For melanoma particularly, restricted research have turned up some unusual and stunning correlations with sure meals. Eating extra citrus fruit has been related to a higher melanoma threat in some, but not all, research, for instance; and red and processed meat has been related to decrease threat of melanoma however a better threat of other cancers.
When it involves correlations between most cancers threat and particular meals, “don’t get overwhelmed by this incomplete data that is yet to be proven,” Dr. Leachman stated. “Hold on to the tried and true things: Eat well, sleep well, exercise well, all in the moderation,” she stated. “That gives you the most resilience you can possibly have against any kind of disease, including cancer.”
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And for melanoma particularly, “the most effective practices we have to prevent melanoma are limiting sun exposure — across the life span, starting in childhood — and skin cancer screening,” Dr. Daniel-MacDougall wrote.
Compared with the restricted knowledge on fish and different dietary elements, there’s much more proof to assist this recommendation, Dr. Leachman agreed. Having had 5 or extra sunburns doubles your lifetime risk of melanoma, and utilizing an indoor tanning mattress can enhance your threat by 75 percent, in line with the Skin Cancer Foundation.
Check your skin repeatedly for any spots that appear to be new, altering or uncommon, and see a physician if you happen to discover one thing regarding, Dr. Leachman stated. “If you see something that looks funny, don’t just blow it off,” she stated. “The earlier you can get it checked, the better off you’re going to be.”
Alice Callahan is a well being and science journalist primarily based in Oregon and a frequent contributor to The New York Times.