health day reporter
The researchers followed more than 490,000 older Americans and found that the 20% who consumed the most fish had about a quarter higher risk of developing the disease over 15 years, compared to the 20% who consumed the least fish.
Still, experts stressed that the results only show a correlation and cannot blame the seafood.
An oncology dietitian who was not involved in the study emphasized the “big picture.”
Because of its benefits – including links to better heart and brain health – experts generally recommend people aim to eat two 4-ounce servings of fish a week, noted Bragagnini, who is also a spokesperson for the Academy of Nutrition and Dietetics.
Fish can be a “great alternative”, she said, for people looking to limit red and processed meats – which are linked to higher risks of certain cancers, including colon and rectal cancers.
It’s not clear, said lead researcher Eunyoung Cho. But one hypothesis is that it’s not the fish, but the contaminants – like mercury and PCBs – that can exist at relatively high levels in some fish.
Previous research has linked Mercury exposure to a higher risk of melanoma and other skin cancers, noted Cho, an associate professor at Warren Alpert Medical School at Brown University in Providence, RI
However, she says, the contaminants theory is just that. “This is the first study to show this association,” Cho said. “We need more research to replicate these results before we can make any dietary recommendations.”
The results, published on June 9 in the journal Cancer causes and control, are based on 491,000 Americans aged 50 to 71 who were followed for 15 years. At first, they completed questionnaires about diet, exercise, and smoking and alcohol consumption habits.
Over the study period, just over 5,000 participants were diagnosed with malignant melanoma, while nearly 3,300 developed melanoma in situ – where “precancerous” melanoma cells lie on the diaper upper layer of the skin but have not penetrated the deeper layers.
Cho’s team found that people in the top 20% fish eaters had a 22% higher risk of malignant melanoma and a 28% higher risk of melanoma in situ, compared to participants who ate the least amount of fish. fish. This top group typically slaughtered nearly 43 grams of fish per day.
These higher risks held when the researchers took into account other lifestyle habits, race, level of education and where people lived.
However, the study lacked details about people’s personal sun habits, said Dr. William Dahut, scientific director of the American Cancer Society. It’s unclear, he noted, whether fish lovers were more likely to have a “beach house” or spend time outdoors.
Dahut, who was not involved in the study, called it “interesting” and worthy of a deeper dive.
“But I wouldn’t tell people not to eat fish because of the risk of melanoma,” he said.
Dahut also pointed to a puzzling finding: People who reported eating more unfried fish or canned tuna had an increased risk of malignant melanoma. But those who ate a lot of fried fish actually had a reduced risk.
Both Cho and Bragagnini agreed that it is difficult to explain the discovery. It’s possible, Cho speculated, that the type of fish matters; she said future studies could examine whether certain varieties of fish are linked to a higher risk of melanoma.
For now, Bragagnini recommended focusing on overall diet, including eating plenty of plant foods like vegetables, fruits, beans, nuts and high-fiber grains. As for fish, she advised cooking or steaming it rather than frying it, which can deplete “good” fats.
When it comes to malignant melanoma, Dahut said the main prevention tactics remain the same: limiting exposure to ultraviolet rays — from the sun or tanning beds — and checking the skin for new growths or changes in skin tone. existing moles.
The American Cancer Society has advice on diet and lifestyle.
SOURCES: Eunyoung Cho, ScD, associate professor, dermatology, Warren Alpert Medical School of Brown University, Providence, RI; Amy Bragagnini, MS, RD, oncology dietician, Mercy Health Saint Mary’s Campus, Lacks Cancer Center, Grand Rapids, Michigan, and spokesperson, Academy of Nutrition and Dietetics, Chicago; William L. Dahut, MD, scientific director, American Cancer Society, Atlanta; Cancer causes and controlJune 9, 2022