Washington, DC: According to a major research of US students, eating more fish, including tuna and non-fried fish, appears to be connected with a higher risk of malignant melanoma.
The accompanying author, Eunyoung Cho, stated: “Melanoma is the sixth most frequent cancer in the United States, with a lifetime risk of one in 38 for white people, one in 1,000 for Black people, and one in 167 for Hispanic people. Although fish consumption has increased in the United States and Europe in recent decades, the findings of prior studies studying the relationship between fish consumption and melanoma risk have been inconsistent. Our findings have revealed a relationship that needs to be investigated further.”
Researchers from Brown University in the United States discovered that those with a median daily fish consumption of 42.8 grams had a 22% higher risk of malignant melanoma than those with a median daily fish intake of 3.2 grams. They also discovered that those with a median daily intake of 42.8 grams of fish had a 28% higher risk of having abnormal cells just in the outer layer of the skin, known as stage 0 melanoma or melanoma in situ, than those with a median daily intake of 3.2 grams of fish. A portion of fish equals about 140 grams of fried fish.
The scientists examined data from 491,367 adults recruited from across the United States for the NIH-AARP Diet and Health Study between 1995 and 1996 to assess the connection between fish intake and melanoma risk. Participants, who were on average 62 years old, indicated how often they ate fried fish, non-fried fish, and tuna in the preceding year, as well as their portion sizes.
Using data from cancer registries, the researchers determined the incidence of new melanomas that occurred over a median of 15 years.
They took into account sociodemographic characteristics, as well as participants’ BMI, physical activity levels, smoking history, daily intake of alcohol, caffeine, and calories, cancer family history, and average UV radiation levels in their local area. During the study period, 5,034 people (1.0 percent) acquired malignant melanoma, and 3,284 (0.7 percent) developed stage 0 melanoma.
The researchers discovered that eating more non-fried fish and tuna was linked to an elevated incidence of malignant melanoma and stage 0 melanoma. Those with a median daily tuna consumption of 14.2 grams had a 20% higher risk of malignant melanoma and a 17% higher risk of stage 0 melanoma than those with a median daily tuna intake of 0.3 grams. In comparison to a median consumption of 0.3 grams of non-fried fish per day, a median intake of 17.8 grams of non-fried fish per day was related to an 18% greater risk of malignant melanoma and a 25% higher risk of stage 0 melanoma. The researchers found no significant links between fried fish consumption and the risk of malignant melanoma or stage 0 melanoma.
According to Eunyoung Cho: “We hypothesize that our findings are due to pollutants in fish such as polychlorinated biphenyls, dioxins, arsenic, and mercury. Previous study has discovered that eating more fish is connected with higher levels of these contaminants in the body, as well as connections between these contaminants and an increased risk of skin cancer. However, because our study did not look at the quantities of these pollutants in the individuals’ bodies, more research is needed to validate this link.”
The researchers emphasize that the study’s observational nature precludes drawing inferences regarding a causal association between fish consumption and melanoma risk. They also did not account for some melanoma risk factors in their analysis, such as mole count, hair color, history of severe sunburn, and sun-related behaviors. Furthermore, because the average daily fish intake was estimated at the start of the trial, it may not be indicative of the participants’ lifelong diets.
Future research, according to the authors, is needed to investigate the components of fish that may contribute to the observed connection between fish intake and melanoma risk, as well as any molecular mechanisms underpinning this. They do not currently advocate any adjustments to fish-eating.