Young adults who have higher levels of mercury in their systems may face a 65 percent increased risk of developing type 2 diabetes later in life, a new study warns.
The findings -- which are the first to link mercury and diabetes in humans -- are alarming in terms of nutrition because eating fish and shellfish is the main source of mercury in people, the researchers added.
They noted that nearly all fish and shellfish contain traces of mercury, but they also contain lean protein and other important nutrients, such as magnesium and omega-3 polyunsaturated fatty acids, which could counter the effects of mercury.
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The study included nearly 3,900 men and women between the ages of 20 and 32 who were free of diabetes in 1987 and followed until 2005. Mercury levels in their toenails were measured, and they were tested for diabetes during the study period. The link between mercury levels and type 2 diabetes risk was established after the researchers controlled for a number of lifestyle and dietary factors.
Compared to other participants, the people with the highest levels of mercury had healthier lifestyles (lower levels of body fat, smaller waist sizes and higher levels of exercise) and also ate more fish.
The findings, published recently in the journal Diabetes Care, highlight the need for people to select seafood known to have low levels of mercury, said study leader Ka He, an epidemiologist at the Indiana University School of Public Health.
Types of seafood with lower levels of mercury include shrimp, salmon and catfish, while those with higher levels include swordfish and shark.
Although the study found an association between higher mercury levels and later development of type 2 diabetes, it did not prove a cause-and-effect relationship.