A new study published by the University of Vermont in Burlington in the FASEB journal has specified that high salt intake is a major risk factor for Multiple Sclerosis, (MS), in people with a specific genetic combination.
Salt has been exposed as an epigenetic risk for MS and is likely to be a trigger for the disease in certain populations. The exact metabolic pathway had not been previously delineated although prior studies had differentiated salt and gender as a risk factor.
The researchers used a mouse model consisting of three genetically differentiated groups of mice and they consumed a diet high in salt or a diet with normal levels of salt. The researchers induced a disease called autoimmune encephalomyelitis, mimicking MS in humans.
“We hope to provide a comprehensive understanding of how and why environmental factors interact with individuals’ unique genetic makeup to influence autoimmune diseases such as MS,” said Dr. Dimitry N. Krementsov, from the University of Vermont in Burlington.
The research study revealed that the three genetic groups had a different expression of symptoms when exposed to salt. In one group, both males and females fed a high-salt diet showed worse symptoms of MS. In the second genetic group, only the females a high-salt diet showed worse symptoms of MS, while in the third group, high salt intake did not affect MS symptoms.
The scientists correlated the difference in immune response to a leaky blood brain barrier; allowing the immune cells to travel into the tissue of the central nervous system and attack the myelin sheath. Nerves lack the ability to conduct nerve impulses properly as the destruction of the myelin sheath also affects the action potential of the cell. Plaques build up along the nerve fiber and the classic symptoms of MS are expressed resulting in increased numbness, paralysis, loss of vision and difficulty with balance and walking.
“This report helps shed light on what can go wrong in individuals with genes that make one susceptible to autoimmune disease. It also helps us understand how much salt is just right for any given individual,” said Dr. Gerald Weissmann, editor-in-chief of The FASEB Journal.
Exacerbation of autoimmune neuroinflammation by dietary sodium is genetically controlled and sex specific, Dimitry N. Krementsov et al., The FASEB Journal, doi:10.1096/fj.15-272542, published August 2015, abstract.