People who regularly eat fish are more likely to develop cancer, according to a new study led by Brown University.
Scientists monitored 491,367 Americans aged between 50 and 71 over an average of 15 years.
They linked consumption of 42 grams a day to a 22 per cent increase in developing malignant melanoma, when compared to people who seldom eat fish. Individuals with a history of cancer were excluded.
Researchers found a positive association between large intakes of total fish, tuna and non-fried fish.
Lead author Eunyoung Cho speculated pollutants absorbed or ingested by the flesh could be to blame.
“We speculate that our findings could possibly be attributed to contaminants in fish, such as polychlorinated biphenyls, dioxins, arsenic and mercury,” she said.
She said previous studies have linked higher fish intake with increased contaminant levels within the body.
These, in turn, have been linked to increased risk of skin cancer.
Noting the study did not measure contaminant concentrations within their subjects, she said “further research is needed to confirm this relationship”.
Experts question aspects of fish study conclusion
Dr Michael Jones from London’s Institute of Cancer Research said the results were “statistically significant” but warned against drawing a conclusion from a single study.
He said the findings would need to be replicated in other countries, where contaminant levels may differ.
“A general healthy balanced diet should include fish and the results from this study do not change that recommendation,” he said.
Professor Gunter Kuhnle from the University of Reading said while the study “challenges the perceived wisdom of healthy fish”, consuming it has other nutritional benefits.
“A large body of research tells us that the recommended amount of fish consumption reduces the risk of cardiovascular disease and improves cognition for many people,” he said.
Professor Kuhnle was one of a number of experts who questioned whether the melanoma increase could be linked to lifestyle.
Some experts pointed to a potential link between fishing and sun exposure.
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