High salt in diet may worsen multiple sclerosis symptoms

A study published in British Medical Journal shows a linkage between higher consumption of salt and multiple sclerosis (MS). Earlier researches had indicated the connection, but the new study gives a more concrete analysis.

Multiple sclerosis is a disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged, disrupting the ability of parts of the nervous system to communicate. Led by Mauricio F Farez of Department of Neurology, Raúl Carrea Institute for Neurological Research, Argentina, the researchers have recommended further investigation to prove beyond doubt the link between salt and MS.  

The researchers assessed the blood and urine samples of 70 people with the relapsing-remitting form of MS to check for levels of salt; a marker of inflammatory activity called creatinine; and vitamin D, low levels of which have been linked to the disease.

Their urine samples were analysed on three separate occasions over a period of nine months to monitor changes in dietary salt intake. Their neurological health was then tracked for two years, between 2010 and 2012. 

For comparison, urinary salt levels were measured in a second group of 52 people with the same type of MS between June and July 2013.

For both the groups, salt intake ranged from less than 2 g (low), 2-4.8 g (moderate) to 4.8 g or more (high) per day. After taking account of influential factors like smoking, age, gender, length of time after diagnosis, weight, treatment and circulating vitamin D, the analysis indicated a link between levels of dietary salt and worsening symptoms.

It was found that people on moderate to high intake in the first group had around three more episodes of worsening symptoms of MS as compared to those consuming low salt. People in the first group were almost four times as likely to have these episodes.

X-rays and scans of the subjects also showed that their disease had progressed further. Those whose dietary salt intake was high were almost 3.5 times as likely to have further progression.

The authors, however, pointed out that this is an observational study, and hence no definitive conclusions about cause and effect can be drawn.

But high salt intake is implicated in various aspects of poor health, they say. The study suggests further research into whether dietary salt reduction could ease MS symptoms or slow the progression of the disease.