Fish contains a lot of omega-3 fatty acids and is therefore considered healthy. But now a study has come to the conclusion that eating too much fish can also make you sick.
Skin cancer is one of the most common types of cancer. In Germany alone, around 230,000 people contract it every year.1 The so-called black skin cancer (malignant melanoma) is usually responsible for a fatal course.2 Eating fish increases the risk of this serious form of skin cancer, according to a new study.
Course of Study
For their study, Brown University researchers used data from 491,367 people identified as part of the National Cancer Institute’s NIH-AARP Diet and Health Study. At the start of the data collection, the subjects, who were 62 years old on average and in good health at the time, reported how high their consumption of fish had been in the previous year. In this way, they informed the researchers how regularly they ate non-fried and deep-fried fish and how large their portions were.
Using information spanning a 15-year period, Brown University researchers analyzed the link between eating fish and developing skin cancer. They also took into account the socio-demographic factors and the body mass index of the participants. Physical activity, smoking, cancer in the family, daily consumption of alcohol, caffeine and calories as well as the average UV radiation in the environment of the participants were considered.
Link between fish consumption and skin cancer
During the study period, 5034 subjects developed skin cancer, more precisely: malignant melanoma. There were also 3,284 cases of melanoma in situ, the initial stage of malignant melanoma. The scientists’ analysis showed that high consumption of fish increases the risk of both forms of skin cancer.3
How Much Seared Fish and Tuna is Too Much?
For example, the risk of skin cancer increased significantly for study participants who ate an average of 14.2 grams of tuna per day compared to people who ate only 0.3 grams per day. They had a 17% higher risk of early-stage melanoma. The risk of developing malignant melanoma was even increased by 20%.
Those who ate an average of 17.8 grams of non-fried fish per day had a 25 percent higher risk of melanoma in situ than people who ate just 0.3 grams per day. The risk of black skin cancer increased by 18%.
While eating fried fish, scientists were unable to find any significant connection with skin cancer.
As stated in a Brown University statement, the study has some limitations.4 Some risk factors for skin cancer have not been taken into account. This included e.g. B. the amount of birthmarks, hair color, frequency of severe sunburn and the extent to which participants were exposed to the sun. The researchers were not even aware of the extent to which fish consumption could have changed over the course of the subjects’ lives. Since the data was also determined in survey form, i.e. via self-disclosure, the study can only make a statement about a connection between a diet with fish and skin cancer diseases. However, he could not prove a causal connection.
However, Eunyoung Cho, co-author of the study and associate professor of dermatology and epidemiology at Brown University, says the research is important “because it is very broad and prospective, which means that fish consumption was studied before cancer developed. “.
Bottom Line: Mercury from fish may increase skin cancer risk
Cho, who has been involved in previous research on the effect of the diet on skin cancer risk, believes that the mercury it contains poses no health hazard, rather than the fish itself.
“We suspect our findings may be due to pollutants in fish such as polychlorinated biphenyls, dioxins, arsenic and mercury,” said Cho. “Previous research has shown that increased consumption of fish is associated with higher concentrations of these substances in the body and has found a connection between them and a higher risk of skin cancer.” Since the current cancer study did not measure how many and which pollutants the subjects in the body, more studies are needed to substantiate causality.