Photo: Salt in pestle and mortar

Salt and MS - the research

There are lots of good health reasons why we should avoid eating too much salt. But does it play a role in MS? We dive into the research.

Is there a link between salt and MS?

When we talk about salt, we’re talking about a molecule called sodium chloride. Sodium plays a number of key roles in the body. For example, changing levels of sodium are essential for messages to be able to travel down nerve fibres.

And recent research has shown that high levels of sodium can affect immune cell signalling, increasing levels of inflammation in the body, both in mice and in people with MS.

With Western diets tending to be quite high in salt, researchers have been looking at whether salt could have an effect on the risk of developing MS, or influencing how quickly MS progresses.

Does salt affect the risk of developing MS?

In a large 2017 study, researchers reported the diets of nearly 100,000 nurses. The data showed the estimated amounts of salt people have has no influence on their risk of developing MS.

Another study looked at the diet of people with clinically isolated syndrome (CIS). Researchers directly measured the level of sodium in people’s urine, as it’s the sodium chloride in salt that’s important. They found the amount of salt people had did not affect the rate at which they developed full MS. It also didn’t influence how their MS developed, as measured by clinical outcomes and MRI.

Do high levels of salt make MS more active?

In 2013 researchers reported that very high levels of salt made symptoms worse in mice with an MS-like condition. They found that salt altered the mice’s immune systems, increasing the levels of a type of immune cell known to cause damage in MS.

One year later, scientists in Argentina linked salt intake to relapse rates. The team measured salt levels in the urine of people with relapsing MS over two years. They found that people with above average salt levels were more likely to have relapses than those with lower salt levels.

But more recent, large studies have found no association between salt intake and MS risk or MS activity.

Is there a link between salt and childhood MS?

Research published in 2016 found no links between salt intake and paediatric onset MS either. 174 children in the US with relapsing remitting MS or CIS were asked to record everything they ate. There was no association between the amount of salt they had and the time to relapse. This included those who had an excessive sodium intake.

Should people worried about MS eat less salt?

We know there’s a molecular link between salt and inflammation, but clinical trials haven’t shown that high levels of salt can affect your MS.

This suggests that people with MS should follow the same advice as everyone else. Guidelines on salt intake for adults and children can be found on the NHS Choices website.