Several teams of scientists have simultaneously published data in the journal Nature suggesting a link.
Salt may activate a part of the immune system that can target the body.
Experts said the findings were very interesting and plausible, but were not a cure for people with MS.
The body's defence against infection can go horrible awry, turning on the body and leading to autoimmune diseases including Type 1 diabetes, rheumatoid arthritis and multiple sclerosis.
Genetics is thought to increase the risk of such diseases, but the world around us also has a major impact. One of the leading theories behind multiple sclerosis is a viral infection, but smoking and a lack of vitamin D may make the condition more likely.
Now researchers believe they have the first evidence that the amount of salt in our diet may also be contributing.