The research, led by Indiana University School of Public Health-Bloomington epidemiologist Ka He, is the first to establish the link between mercury and diabetes in humans.
The main source of mercury in humans comes from the consumption of fish and shellfish, nearly all of which contain traces of mercury.
Fish and shellfish also contain lean protein and other nutrients, such as magnesium and omega-3 polyunsaturated fatty acids, that make them important to a healthy diet.
They also ate more fish, which is a possible marker of healthy diet or higher social economic status.
More From This Section
The study, which involved 3,875 men and women, established the link between mercury levels and type 2 diabetes risk after controlling for lifestyle and other dietary factors such as magnesium and omega-3 polyunsaturated fatty acids, which could counter the effects of the mercury.
"It is likely that the overall health impact of fish consumption may reflect the interactions of nutrients and contaminants in fish. Thus, studying any of these nutrients and contaminants such as mercury should consider confounding from other components in fish," the authors wrote.
"In the current study, the association between mercury exposure and diabetes incidence was substantially strengthened after controlling for intake of LCn-3PUFAs (omega-3) and magnesium," they said.