Is high fish consumption really linked to cancer risk?

“Melanoma is the fifth most common cancer in the United States, and the lifetime risk of developing melanoma is one in 38 for whites, one in 1,000 for blacks, and one in 167 for Hispanics.” ,​ Eunyoung Cho, the corresponding author, observed.

“Although fish consumption has increased in the United States and Europe in recent decades, the results of previous studies investigating associations between fish consumption and melanoma risk have been inconsistent. Our results identified an association that requires further investigation.

What does the data say?

The study was based on data from the NIH-AARP Diet and Health Study, which is a large, long-term study examining the relationship between diet and health involving 3.5 million US citizens. Brown’s researchers analyzed data from about 500,000 adults.

They found that people who ate around two servings of fish per week – a daily average of 42.8 grams – had a 22% higher risk of malignant melanoma compared to people who ate a daily average of just 3.2 grams. .

The researchers also found that people who ate two servings of fish a week had a 28% increased risk of developing abnormal cells in the outer layer of the skin only – known as stage 0 melanoma or melanoma. in situ – compared to the low consumption group.

The study found similar associations with specific types of fish. Participants with the highest intakes of tuna (about 14 grams per day) and unfried fish (about 18 grams per day) both had about a 20% higher risk of developing malignant melanoma compared to those with the lowest contributions.

But when the fish was fried, the association reversed. Those who ate the most fried fish (about 9 grams per day) had a lower risk of developing malignant melanoma than those who did not eat fried fish.

Should we rethink the advice to eat fish?

The UK’s National Health Service recommends people eat two servings of fish a week because of its association with health benefits, including cardiovascular health. With fish long considered a healthy protein and included in national dietary guidelines, what could possibly be behind these startling findings?

“We speculate that our findings could possibly be attributed to contaminants in fish, such as polychlorinated biphenyls, dioxins, arsenic and mercury,”suggested Eunyoung Cho.

“Previous research has shown that high fish consumption is associated with higher levels of these contaminants in the body and has identified associations between these contaminants and a higher risk of skin cancer. However, we note that our study did not investigate the levels of these contaminants in participants’ bodies and therefore further research is needed to confirm this relationship.

But before overturning the conventional wisdom that eating fish is an important part of a healthy diet, the European Food Information Council (EUFIC) has highlighted some issues that need to be considered. .

“As an observational study, this research is based on what the researcher observed, without any experimentation or manipulation of the research subjects. Such studies cannot prove a direct causal link – they only demonstrate associations,”EUFIC experts pointed out.

Other limitations of the research include the reliance on “food frequency” questionnaires which, although a validated way to assess diets, may mean that intake estimates in fish are inaccurate because they rely on people’s ability to calculate their own dietary intake.

It is important to note that EUFIC pointed out: “Any risk of ‘two servings of fish per week’ may be outweighed by the benefits: fish, especially fatty fish, has been linked to numerous health benefits.”

Fish consumption and melanoma risk in the NIH-AARP Diet and Health Study
Cander Causes and Control
Authors: Yufei Li, Linda M. Liao, Rashmi Sinha, Tongzhang Zheng, Terrence M. Vance, Abrar A. Qureshi and Eunyoung Cho

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