Study finds fish linked to skin cancer risk, but you don’t have to give up seafood

  • Higher consumption of tuna and other unfried fish has been linked to an increased risk of melanoma, but more research is needed.
  • Experts say you don’t have to stop eating fish.
  • Instead, they suspect eating low-toxin fish might be better.

Higher consumption of tuna and other unfried fish was associated with an increased risk of melanoma, the most serious type of skin cancer, according to a new study.

The researchers suspect that this link may be due to toxins rather than the fish itself.

“We speculate that our findings could possibly be attributed to contaminants in fish, such as polychlorinated biphenyls, dioxins, arsenic and mercury,” said study author Eunyoung Cho, ScD, Professor fellow in dermatology and epidemiology at Brown University, in a news release. .

However, the researchers caution against making any changes to your fish intake, saying more research is needed to better understand the link observed in the study.

The study was published June 9 in the journal Cancer causes and control.

Although melanoma accounts for only a small fraction of skin cancers, it causes the vast majority of skin cancer deaths, according to the American Cancer Society (ACS).

To see if there was a link between melanoma risk and fish consumption, the authors of the new paper analyzed data from more than 490,000 adults who participated in the NIH-AARP Diet and Health Study of the National Cancer Institute between 1995 and 1996.

Participants reported the frequency and amount of fish they ate, including fried fish, unfried fish such as flounder and cod, and canned tuna.

The researchers obtained data from cancer registries to determine how many participants developed melanoma over the next 13 to 16 years.

They also tried to take into account other factors that could affect a person’s risk of melanoma, such as body mass index, level of physical activity, smoking status, family history of cancer, alcohol and calorie intake and participants’ average local ultraviolet (UV) radiation levels.

Researchers found that people who ate the most fish per day on average (42.8 grams) had a 22% higher risk of malignant melanoma than those with the lowest average daily intake (3, 2 grams).

They also had a 28% higher risk of developing abnormal cells only in the outer layer of the skin; this is called melanoma in situ.

A portion of cooked fish is around 85 grams, although this will vary depending on your weight. A standard can of tuna weighs 142 grams.

Additionally, people in the study who ate 14.2 grams of tuna a day on average had a 20% higher risk of malignant melanoma and a 17% higher risk of melanoma in situ compared to those who ate 0 .3 grams per day on average.

For those who ate an average of 17.8 grams per day of unfried fish, the risk of malignant melanoma was 18% higher than those who ate 0.3 grams per day. Their risk of melanoma in situ was also 25% higher.

The researchers found no link between eating fried fish and the risk of either type of melanoma. However, even the people who ate the most fried fish only averaged 7.1 grams a day.

Previous research on the link between fish consumption and melanoma risk has yielded mixed results, the researchers wrote. Some of these studies, however, were not as rigorous as the current one.

“This [new] The study is important because it is very large and is prospective in design, meaning that fish consumption was assessed before the development of cancer,” said Dr Cho.

However, there are several limitations to the new study, which should be addressed in future research.

For example, researchers estimated people’s UV exposure based on average levels of UV radiation where they lived. This does not take into account how long they have spent in the sun or if they have been exposed to the sun due to their work.

The researchers also did not have information on other melanoma risk factors like the number of moles people have, the color of their hair and skin, or their history of severe sunburn.

They also only measured food intake, physical activity and other behaviors at the start of the study, but these may have changed over time.

Also, this is an observational study, so it cannot prove that eating fish causes melanoma, only that there is a link between the two.

This does not mean that the results should be ignored.

Fish tissue can contain contaminants such as mercury and polychlorinated biphenyls (PCBs). Levels vary from place to place, but the concentration can increase as you move up the food chain, and larger predators tend to have higher levels.

Mercury, pcb and other toxins are also a potential health hazard to people who consume them.

A previous study of over 20,000 Swedish women found that dietary PCB exposure was associated with a four times higher risk of malignant melanoma compared to women who ate the lowest amount of fish.

The researchers in this study also estimated the consumption of omega-3 fatty acids. Women consuming the most of these healthy fats had an 80% lower risk of melanoma, even after the researchers took into account their dietary exposure to PCBs.

This lines up with another study, which found that people who ate higher amounts of fish had a lower risk of melanoma, and higher fruit and vegetable intake was also linked to a lower risk.

However, neither of these previous studies nor the new study measured the level of mercury, PCBs or other contaminants in participants’ blood.

This step would be necessary to distinguish the benefits of fish consumption from the harmful effects of toxins in fish tissue.

“Our study did not investigate the concentrations of these contaminants in participants’ bodies, and therefore further research is needed to confirm this relationship,” Cho said.

It’s too soon to change your fish intake based on this study, especially since fish and other seafood are an excellent source of protein, healthy fats, calcium and vitamin D.

But you can take steps to minimize your exposure to toxins.

“The good news is that there are an abundance of low-mercury seafood options to choose from,” said Whitney Linsenmeyer, PhD, RD, spokesperson for the Academy of Nutrition and Dietetics and professor. nutrition assistant at Saint Louis University.

These to understand anchovies, black bass, catfish, cod, plaice, herring, lobster, salmon, sardines, freshwater trout and whiting.

Certain groups are more vulnerable to mercury, which poses other better-studied health risks.

“The groups that should be most concerned about mercury levels in fish are pregnant or breastfeeding women, those who could become pregnant, and young children,” Dr. Linsenmeyer said.

She recommends that these people choose seafood with higher levels of essential fatty acids but lower levels of mercury, such as salmon, anchovies, sardines, Pacific oysters and freshwater trout.

The United States Food and Drug Administration has also advice on eating fish safely.

In addition, the Environmental Protection Agency and state and local agencies publish fish advisories. These warn the public to limit or avoid eating certain species of fish or shellfish due to contamination.

“[Advisories] can be especially helpful when eating fish that you caught yourself or got from a friend,” Linsenmeyer said.

And if you’re concerned about melanoma, remember that one of the best ways to reduce your risk of skin cancer is to follow ACS sun protection tips every time you go outside.

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