Exposure to even low levels of mercury through fish consumption can increase the risk of autoimmune disorders in women of childbearing age, latest research shows.
Autoimmune disorder is a medical condition where an over-stimulated immune system fails to recognise healthy tissues and attacks them. It is one of the ten leading causes of death among women across the world.
Type 1 diabetes, grave's disease, psoriasis, rheumatoid arthritis, multiple sclerosis and pernicious anaemia are some of the autoimmune diseases. The disorder can cause tiredness, joint pain, weight gain, rashes and muscle aches, depending up on the part that is affected by the disorder like joints, thyroid or skin. The exact reasons which lead to this occurrence are yet to be completely known.
"We don't have a very good sense of why people develop autoimmune disorders," lead author of the study Dr Emily Somers, from University of Michigan, said in a news release. "A large number of cases are not explained by genetics, so we believe studying environmental factors will help us understand why autoimmunity happens and how we may be able to intervene to improve health outcomes. In our study, exposure to mercury stood out as the main risk factor for autoimmunity."
Data for the study came from the National Health and Nutrition Examination Survey conducted between 1999 and 2004. The study mainly focused on women aged between 16 and 49.
Women with higher levels of mercury also had higher levels of autoantibodies, certain proteins released by the body's immune system when it fails to identify healthy tissues. These proteins may be signalling the risk of developing autoimmune diseases later in life, according to the authors.
"The presence of autoantibodies doesn't necessarily mean they will lead to an autoimmune disease," Somers said. "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.
"For women of childbearing age, who are at particular risk of developing this type of disease, it may be especially important to keep track of seafood consumption."
Humans mainly get exposed to mercury through the consumption of seafood. Almost all fish and shell fish contain mercury. So women who are pregnant, planning to become pregnant, lactating and small children are always recommended to limit their seafood intake, mainly Shark, Swordfish, King Mackerel, or Tilefish, to two servings a week.
Industries play a huge role in increasing the levels of mercury in the environment. On reaching the ocean, this mercury gets transformed to methylmercury and gets absorbed by fish.