New studies suggest that high salt intake can increase the risk of some autoimmune diseases, including multiples sclerosis. Salt not only raises the blood pressure but can trigger the body's immune system to attack itself.
Researchers explain that genetics are not involved in the significant rise of autoimmune disease: Environmental factors appear to have contributed to the trend.
The findings of the study were discovered when researchers directed their attention toward inflammatory cells. These cells are utilized by the body's immune system to guard against bacterial, viral, fungal and parasitic infections. Autoimmune diseases such as multiple sclerosis and Type 1 diabetes are cases in which inflammatory cells attack healthy cells.
When researchers detected that higher levels of inflammatory cells were found in people who consumed fast food, they took an interest in looking closer at the effects of salt on the immune system.
"The diet does affect the autoimmune system in ways that have not been previously recognized," said senior study author Dr. David Hafler, a professor of neurology and immunobiology at the Yale School of Medicine in New Haven, Conn.
Mice were used in the study, although animal studies do not always reflect the results of human trials. Results of the study showed how mice that were given a diet high in salt produced infection-fighting cells associated with autoimmune diseases.
The mice developed "autoimmune encephalomyelitis," a severe form of multiple sclerosis. High levels of salt appear to accelerate the creation of helper cells known as "T-cells" and escalates the immune response.
"We don't think salt is the whole story. It's a new, unexplored part of it, but there are hundreds of genetic variants involved in autoimmune disease and environmental factors, too," said Hafler.
More studies will offer a way to test if a diet in lower salt may be used to treat autoimmune disease in humans.
"They have now identified a biomarker, so you could treat people with a low-salt diet and then check for the marker in cells using cell cytometry, for example," said Dr. John L'shea, director of intramural research at the U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases, in Bethesda, Md.
Findings of the study were published in the March 6 issue of the journal Nature.