An intriguing new study has described a clear association between food allergies and disease activity in multiple sclerosis (MS) patients. The correlation adds weight to the growing hypothesis suggesting the inflammatory activity behind MS is modulated, to a degree, by a mechanism in the gut.

"Some multiple sclerosis patients with significant allergies would complain of frequent relapses associated with their allergic episodes," explains Tanuja Chitnis, senior author on the new research. "We felt that the most likely mechanism associated with allergy and its influence on MS would be related to inflammatory activity."

To better home in on this compelling correlation between allergies and MS disease activity, a team from Brigham and Women's Hospital looked at data from over 1300 patients enrolled in a longitudinal MS research project. The subjects were divided into four groups: those with no known allergies, and those with either food, environmental, or drug allergies.

The striking discovery was that subjects with food allergies displayed significantly increased signs of disease activity over all other groups. Disease activity was measured using a variety of factors including the number of flare-ups since initial diagnosis, and MRI scans tracking for gadolinium-enhancing lesions. Environmental and drug allergies seemed not to influence the disease's inflammatory activity in comparison to subjects with no known allergies, but the presence of a food allergy was significantly associated with more flare-ups and MRI-tracked lesions.

"It is interesting that this association was only found with food allergies and not other types of allergies, which might have been expected had this solely been an immune deviation issue," says Chitnis. "There has long been a hypothesis of the gut being related to the immune system, and this really points to a stronger association than previously understood."

This observational study of course suffers from many limitations. There is no clarity over whether a food allergy needs to be specifically triggered to enhance the MS-related effects. It seems to be implied that it is merely the presence of a food allergy that seems to accompany a higher degree of MS inflammatory activity. One of the hypotheses behind this correlation suggests a food allergy signals a major alteration in a person's gut bacteria, which could be modulating neuroinflammatory activity.

A fascinating study published last month revealed for the first time that certain immune cells found to originate in our gut may be influencing MS-related inflammation in the brain. Another study from 2017 found levels of specific gut bacteria seemed to correlate with the disease's activity in the brain.

It's incredibly early days for this research so there is a lot we simply still do not know. It is unclear exactly how our gut bacteria could be influencing MS activity in the brain. Maybe the correlation between MS activity and food allergies is simply a reflection of the same genes triggering both conditions? Chitnis and his team are confident these new findings will help broaden the scope of investigation into new treatments for this devastating disease.

"This research opens up a new way of thinking about the immune mechanisms in MS," Chitnis says.

The new study was published in the Journal of Neurology, Neurosurgery & Psychiatry.