The study included 491,367 US adults aged around 62 who reported the frequency and portion sizes of their consumption of fried fish, non-fried fish, and tuna over the preceding year.

The NHS recommends two servings of fish per week for a healthy diet, including one portion of oily fish weighing around 140g (4.9oz).

However, U.S. researchers have cautioned that two weekly servings may increase the chance of developing malignant melanoma, the deadliest type of skin cancer.

People whose typical daily diet of fish was 42.8g (about 300g per week) had a 22 percent increased risk of malignant melanoma than those whose daily intake was only 3.2g.

Those who ate more fish were also 28 percent more likely to acquire abnormal cells in the outer layer of the skin, which is known as stage 0 melanoma or melanoma in situ and is also known as pre-cancerous cells.

The study included 491,367 US individuals aged approximately 62 who reported the frequency with which they consumed fried fish, non-fried fish, and tuna over the preceding year, as well as the portion sizes.

Using data gathered from cancer registries, researchers assessed the incidence of melanoma cases over 15 years.

In addition to weight, smoking, and drinking history, and whether or not there was a family history of cancer, they considered additional variables that could have influenced the results.

1% of individuals got malignant melanoma, while 0.7% of individuals developed stage 0 melanoma.

While no significant association was discovered between eating fried fish and skin cancer, consuming 17,8g of non-fried fish daily was related to an 18 percent increased risk of malignant melanoma and a 25 percent increased risk of stage 0 melanoma compared to consuming merely 0.3g.

People who consumed 14.2g versus 0.3g of tuna per day were likewise shown to have a 20 percent increased risk.

Author Eunyoung Cho stated, “We hypothesize that our findings may be attributable to pollutants in fish, including polychlorinated biphenyls, dioxins, arsenic, and mercury.”

Dr. Michael Jones, a senior staff scientist in genetics and epidemiology at the Institute of Cancer Research, stated that it is probable that persons who consume more non-fried fish or tuna have other lifestyle behaviors that raise their melanoma risk.

“The authors hypothesize that the association may be related to pollutants in fish, but they did not measure the levels of these contaminants in the subjects,” he said.

“It is important to note that eating two meals of fish per week…can be a way to include important nutrients such as omega-3 fatty acids in a balanced diet, and this study should not dissuade people from having fish in a healthy diet.”