Young adults who have excessive levels of mercury in their bodies could be at much greater risk of developing type 2 diabetes later in life, according to a new study which is the first of its kind to associate mercury exposure with diabetes in humans.
Fish and particularly shellfish is the main source of mercury in our diet. However, these also contain lean proteins and other nutrients such as omega 3 and polyunsaturated fatty acids that are essential for good health .
For the study, researchers at the Indiana University School of Public Health followed nearly 3,900 people aged 20-31 between 1987 and 2005. The participants, all of whom were free of diabetes at baseline, had mercury levels in their toenails measured and were also tested for type 2 diabetes during the study period.
People with high mercury levels had lower BMIs (body mass index), smaller waist sizes and greater fitness levels – indicating healthier lifestyles.
But after controlling for dietary factors, such as intake of omega-3, the team found that they also had a 65% increased risk of type 2 diabetes.
Epidemiologist Ka He, lead author of the study, said the findings highlight the need for people to choose seafood known to have low levels of mercury, as this might help people gain the health benefits associated with fish and shellfish while avoiding the risk of disease.
Seafood with lower mercury levels includes shrimp, salmon and catfish, while higher levels are found in swordfish and shark.
Ka He said: “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.
“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.”
The study findings are published in the journal Diabetes Care.
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