Some fish may contain relatively high levels of mercury. (Photo: EPA)
UNITED STATESThursday, February 12, 2015, 03:40 (GMT + 9)
Mercury exposure through consumption of certain fish, even at low levels generally considered safe, can cause autoimmune disorders, especially on childbearing age women, a study by the University of Michigan Health System suggests.
As many autoimmune cases cannot be explained by genetics, researches started to see which environmental and nutritional factors could intervene causing such disorders.
Pregnant women, nursing mothers and young children are usually recommended to include important fish consumption in their diets.
However, fish such as swordfish, king mackerel and tilefish contain high levels of mercury while shrimp, canned light tuna and salmon have lower levels.
The study establishes that the higher mercury exposure, the higher the rate of proteins called "autoantibodies". These proteins are produced when a defective immune system cannot distinguish healthy cells from the harmful ones, and its presence is considered an indicator and/or precursor of autoimmune disease.
"The presence of autoantibodies doesn't necessarily mean they will lead to an autoimmune disease," the study author, Emily Somers, notes. "However, we know that autoantibodies are significant predictors of future autoimmune disease, and may predate the symptoms and diagnosis of an autoimmune disease by years.”
Somers an associate professor in the departments of internal medicine in the division of rheumatology, environmental health sciences, and obstetrics & gynaecology at the University of Michigan Medical and Public Health Schools in Ann Arbor and her colleagues informed their findings in Environmental Health Perspectives journal.
Although the study found an association between mercury exposure and the possible development of autoimmune diseases, it does not establish that mercury directly causes the diseases.