Researchers from Brown University found that higher levels of fish intake compared to lower intake was associated with an increased risk of developing melanoma type skin cancer.

For their study, researchers analyzed data for people in the US in the NIH-AARP Diet and Health Study of whom the 491,367 adults were recruited between 1995 to 1996. The participants were on the average of 62 years old reported on dietary frequency of fried-fish, non-fried fish, and tuna over the past year and the portion sizes. Via cancer registries, the investigators calculated the incidence of new melanomas that developed over a median 15 years.

The researchers also accounted for certain data like BMI, physical activity levels, smoking, alchol intake, family history, UV exposure, etc.

They found that compared to eating 3.2 grams of fish daily, eating 42.8 grams lead to a 22% higher risk of developing melanoma. Additionally, median intake of 42.8 grams of fish had a 28% increased risk of developing abnormal cells in the outer layer of the skin, aka stage 0 melanoma, compared to those who ate 3.2 grams of fish per day.

Furthemore, those who had a median daily intake of tuna of 14.2 grams had a 20% higher risk of malignant melanoma and 17% higher risk of stage 0 melanoma, compared to people who ate 0.3 grams of tuna per day.

A median intake of 17.8 grams of non-fried fish per day led to an 18% higher risk of melanoma and a 25% increased risk of developing stage 0 melanoma, compared to eating 0.3 grams.

Oddly, there was no association of melanoma development with eating fried fish.

The authors speculated their results were due to contaminants found in fish. However, they did not determine the levels of the contaminants in the fish that were eaten nor in the participants.

Either way, their results should encourage people to stop eating fish and to support regulations that cut down the amount of pollution that goes in the water.

Their results were published in the journal Cancer Causes & Control.

Y Li et al. Fish intake and risk of melanoma in the NIH-AARP diet and health study. Cancer Causes & Control. DOI: 10.1007/s10552-022-01588-5