Eating too much sodium could make multiple sclerosis symptoms worse and increase the risk of further damage, according to a small study published in the Journal of Neurology Neurosurgery & Psychiatry.

“This is an intriguing, preliminary observation that suggests a high sodium diet does more than affect the cardiovascular system,” said Elliott Antman, M.D., president of the American Heart Association and cardiologist and professor of medicine at Brigham and Women’s Hospital in Boston, Massachusetts. “High sodium diets may be associated with a higher risk of autoimmune disorders.”

Multiple Sclerosis occurs when the body’s immune system attacks the body’s central nervous system, interfering with the transmission of nerve signals between the brain, spinal cord and the rest of the body, according to the National Multiple Sclerosis Society. Scientists believe it may be caused by environmental factors in people predisposed to respond, although the cause is unknown.

People with multiple sclerosis who consumed moderate to high amounts of sodium had about three more episodes of worsening symptoms. They were also four times more likely to have them than those consuming the least amount.

Researchers also found a link between sodium intake and the progression of the disease through neurological imaging. People who consumed high amounts of sodium were nearly 3.5 times as likely to show signs of deterioration.

To get the data, researchers evaluated sodium in urine samples of 70 people with the relapsing-remitting form of multiple sclerosis to assess sodium intake by assessing sodium excretion, and vitamin D in blood samples, as deficiencies have been linked to MS.

Urine samples were taken three different times over nine months and neurological health tracked between 2010 and 2012.

Researchers measured urinary sodium levels in a second group of 52 people with the same type of multiple sclerosis between June and July 2013. Similar results were obtained for this comparison group.

Sodium intake averaged more than 4,000 milligrams a day in both groups. Daily sodium intake was categorized as under 2,000 mg; 2,000-4,800 mg; and 4,800 mg or more. Men had higher sodium intake than women.

Researchers factored out possible influencers, such as smoking, age, gender, length of time after diagnosis, weight, treatment and circulating vitamin D.

Because it was an observational study, it was not powered to reach definite conclusions about cause and effect. Higher levels of sodium in the urine could reflect greater disease activity rather than the other way round, the authors point out.

The study results, coupled with some studies published previously, show that excess sodium contributes to tissue inflammation and may be implicated in other aspects of poor health, said Mark Creager, M.D., director of the Vascular Medicine Program at Brigham and Women’s Hospital and president-elect of the American Heart Association.

According to the American Heart Association, sodium increases blood pressure in some people because it holds excess fluid in the body, creating an added burden on the heart. Too much salt adversely affects the heart, kidneys and blood vessels.

High blood pressure contributes to heart disease and stroke, two of the top causes of death worldwide.

The current findings support further study into whether dietary sodium reduction could ease multiple sclerosis symptoms or slow its progress, according to researchers.

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