Study: Fish consumption increases skin cancer risk
People who enjoy eating fish may have an increased risk of skin cancer. A large-scale study from the US has now revealed a possible connection.
A new study has identified a link between fish consumption and an increased risk of melanoma, a serious form of skin cancer.
Melanoma is widely considered the most dangerous form of skin cancer; it is the most invasive and carries the highest mortality risk. Melanoma is rare, and a large proportion of cases are caused by the sun.A British study found that 86% of melanomas are caused by ultraviolet radiation from the sun.
Furthermore, a person's risk of melanoma doubles if they have had more than five cases of sunburn. (But even a single severe case of sunburn during childhood or adolescence can double the risk.)
However, our diet may also play a role, as a recent analysis by a team from Brown University shows.
Skin cancer research
The study was published in the journal Cancer Causes and Control. It included 491,367 adults in the United States with an average age of 62.
Participants reported their consumption of fried fish, non-fried fish or seafood (such as lobster, crab, clams and shrimp) as well as tuna, including products packed in oil or water.
Using data from cancer registries, the researchers tracked the occurrence of new melanomas among participants over an average period of 15 years. They took into account sociodemographic factors as well as smoking, body mass index, physical activity, family history of cancer, and the average UV radiation levels in participants' regions.
They also took into account participants' daily consumption of alcohol, caffeine and calories.
During the study period, 1% of participants (5,034 individuals) developed a malignant melanoma. 0.7% (3,284) developed a stage 0 melanoma (also known as melanoma in situ), in which the cancer cells are still confined to the outermost layer of the skin and have not spread to the second layer.
The researchers found that consuming non-fried fish or tuna increases the risk of both forms of melanoma.
Almost all fish contain pollutants such as mercury
The study results show that consuming larger amounts of fish, including tuna and non-fried fish, appears to be associated with a higher risk of melanoma. People who consumed an average of 42.8 grams of fish per day had a 22% higher risk of malignant melanoma and a 28% higher risk of developing early-stage skin cancer, also known as melanoma in situ. These figures were based on a comparison with people who eat an average of 3.2 grams of fish per day.
The researchers found no significant association between fried fish and melanoma risk.
Mercury and fish
Study author Eunyoung Cho is a professor of dermatology and epidemiology at Brown University, an Ivy League research university in Rhode Island.
Cho suspects that the link between seafood consumption and cancer may be due to the presence of biocontaminants such as mercury.
«We speculate that our findings may be attributable to contaminants in fish such as polychlorinated biphenyls, dioxins, arsenic, and mercury«, said Cho in a statement. «Previous research has found that higher fish consumption is associated with higher concentrations of these pollutants in the body, and has identified a link between these pollutants and a higher risk of skin cancer.«
«Mercury consumption in the US comes primarily from fish«, said Cho. «So if mercury is linked to skin cancer, it stands to reason that fish consumption is linked to it as well.«
Today, almost all fish contain traces of mercury, and humans bear the primary responsibility for this.According to a report by the United Nations Environment Programme from 2018, human activities have increased the total concentration of mercury in the atmosphere by approximately 450% above natural levels.
High concentrations of mercury can damage the kidneys and liver, as well as the nervous, digestive, and immune systems. They can also be fatal.
Cho pointed out that the study examined neither mercury nor other pollutants. Therefore, «further studies are required to confirm this connection«.
A balanced diet has a positive effect not only on well-being but also on health. In contrast, a diet high in a certain amino acid is thought to promote depression; this amino acid is found primarily in animal-based foods.
