Eating fish could increase your risk of skin cancer, study says

Is it time to go vegan now?

Emerging research shows eating fish twice a week could make consumers more likely to develop melanoma, a dangerous skin cancer.

While twice per week is the recommended amount of fish or shellfish to eat, scientists who studied people eating the advised two servings discovered those consumers were one-fifth more likely to develop melanoma.

Those who ate the recommended amount were compared to people who consumed much less, revealing the latter were at a lower risk of cancer.

The study, conducted by researchers at Brown University and published in the Cancer Causes & Control journal Thursday, tracked the 491,367 participants for 15 years, reporting over 5,000 malignant melanoma cases. In addition, more than 3,000 cases of melanoma in situ were reported, which means cancer cells were found in the top layer of the epidermis sometimes called “precancer.”

They confirmed a correlation between a higher weekly fish and seafood intake and the presence of cancer cells, concluding consumers were 22% more likely to develop malignant melanoma and 28% more likely to have melanoma in situ.

However, fried fish did not have that same association.

“Fried fish intake was inversely associated with risk of malignant melanoma,” authors wrote.

The study did not specify whether any of the seafood — which includes “flounder, cod, shrimp, clams, crabs, lobster and others” — used was examined while raw.

But Dr. Eunyoung Cho, a dermatologist and the lead study author, said the team’s results need further investigation.

“We speculate our findings could possibly be attributed to contaminants in fish, such as polychlorinated biphenyls, dioxins, arsenic and mercury,” she said. “Previous research has found higher fish intake is associated with higher levels of these contaminants within the body and has identified associations between these contaminants and a higher risk of skin cancer.”

Yet, the study did not investigate the presence or concentration of any contaminants in people’s bodies. They did, however, look at participants’ weight, diet, smoking behaviors and alcohol consumption, as well as their UV exposure in their geography, but did not consider mole counts, past sun exposure and burns, hair color or whether they had worn sunscreen.

Lighter, natural skin color, easily burned or freckled skin, blue and green eyes, blonde or red hair, a larger number of moles, family history of skin cancer and age all play a role in heightened skin cancer risk, according to the Center for Disease Control. While genetics are immutable, one action people can take is actively wearing sunscreen to reduce UV exposure.

While London’s Institute of Cancer Research’s Dr. Michael Jones was not involved with the study, he said the results aren’t that fishy — they are “unlikely due to chance,” despite more research being necessar.

“A general healthy balanced diet should include fish and the results from this study do not change that recommendation,” he said, adding that people who had an increased risk of skin cancer might have other unknown habits that contributed.

Meanwhile, another study emerged Wednesday that revealed consuming approximately 430 grams, or 15 ounces, of dairy was tied to a higher risk of prostate cancer in men compared to those who only consumed 20 grams, or less than an ounce.

The study, conducted by Loma Linda University Health in California, studied more than 28,000 men in the US who were, at first, cancer-free. Eight years later, a staggering 1,254 men had been diagnosed with cancer. 

Participants who consumed more dairy on average had a 62% higher risk of developing cancer than those who rarely consumed it, the researchers said in their study, which was published in the American Journal of Clinical Nutrition. Yet, the team said cheese and milk were not linked to prostate cancer.

The US Drug Administration advises adults to consume three cups of dairy per day in order to ingest the calcium and vitamin D the body needs, which includes milk, cheese, yogurt and even calcium-fortified foods and drinks.

In the study, the researchers found no link between cancer to any dairy-free sources of calcium, such as fortified cereals, nuts, seeds and vegetables, which could suggest calcium isn’t the culprit.

Study leader Dr. Gary Fraser, who is also the university’s internal medicine and cardiovascular disease expert, said dairy foods are “casually” related to cancer. He hypothesized that the sex hormones present could be the cause since three-quarters of milk comes from pregnant cows, he said, and prostate cancer is a “hormone-responsive cancer.”

The team also found there were “minimal” changes in risk of cancer between nonfat, reduced-fat or full-fat milk, and they found increased dairy consumption did not mean an equally increased risk of cancer.

“If you think you’re at higher than average risk, consider the alternatives of soy, oat, cashew, and other nondairy milks,” Dr. Fraser said, warning men at higher risk to “be cautious.”