It's not yet known whether an allergy can cause the MS in the first place, but researchers do know that sufferers experience a relapse soon after a reaction to food.
The common factor seems to be inflammation in the gut that is triggered by an allergic reaction, say researchers at the Brigham and Women's Hospital.
They discovered the connection when they surveyed 1,349 MS sufferers. Although they were asked to reveal any allergic reaction to food, environmental factors or drugs, only those with a food allergy suffered severe and frequent relapses.
This suggests that MS isn't an immune reaction but is more closely associated with the gut and inflammatory responses to foods.
The discovery ties in with case notes that have shown how sufferers seem to suffer relapses after an allergic reaction—but nobody had been sure it was a reaction only to food.