Eating two portions of fish per week has been linked to an increased risk of skin cancer, a study suggests.
The NHS recommends that people should eat at least two portions of fish per week, including one of oily fish, with a portion weighing around 140g.
But now researchers in the US have warned that this amount may be putting people at risk of malignant melanoma, the most deadly form of skin cancer.
Other experts said fish was an important healthy food and there was no need to stop eating it.
What is melanoma?
Melanoma is caused by skin cells that begin to develop abnormally
The most common sign of melanoma is the appearance of a new mole or a change in an existing mole
Melanoma skin cancer is the 5th most common cancer in the UK
Around 16,000 new cases of melanoma are diagnosed each year
See a GP if you notice any change to your moles. They'll refer you to a specialist clinic or hospital if they think you have melanoma
The main treatment for melanoma is surgery, although treatment will depend on circumstances
Experts from Brown University in America, found that people whose typical daily intake of fish was 42.8g had a 22% higher risk of malignant melanoma than those whose typical daily fish intake was just 3.2g.
Those eating more fish also had a 28% increased risk of developing abnormal cells in the outer layer of the skin.
Their findings were based on a study of nearly half a million adults in the US.
They took into account factors that could influence the results, such as people’s weight, whether they smoked or drank alcohol, diet, family history of cancer and average UV radiation levels in their local area.
Overall, 5,034 people (1%) developed malignant melanoma during the study period and 3,284 (0.7%) developed stage 0 melanoma.
A breakdown of the results showed that total fish intake was linked to higher risks.
Meanwhile, people whose typical daily tuna intake was 14.2g had a 20% higher risk of malignant melanoma compared with those with a typical intake of 0.3g.
Eating 17.8g of non-fried fish per day was associated with an 18% higher risk of malignant melanoma and a 25% higher risk of stage 0 melanoma, compared with eating just 0.3g.
However, no significant link was found between eating fried fish and skin cancer.
Author Eunyoung Cho said previous studies had been inconsistent, adding: “Our findings have identified an association that requires further investigation."
The team encountered several limitations to their study that experts did not account for, including some established risk factors for melanoma, such as mole count, hair colour, history of severe sunburn and whether people sunbathed or wore sun cream.
Also, average daily fish intake was calculated at the beginning of the study and may not represent how much people eat over the course of their lives.
Dr Michael Jones, senior staff scientist in genetics and epidemiology at the Institute of Cancer Research, London, said: “The authors found a higher intake of non-fried fish and tuna was associated with melanoma. These results were statistically significant and therefore unlikely due to chance.
“A general healthy balanced diet should include fish and the results from this study do not change that recommendation.”