Now, an observational analysis published online in the Journal of Neurology, Neurosurgery & Psychiatry on December 18 shows MS patients with food allergies had more relapses and an increase in active lesions.

Assessing Allergies in MS

To test the association between allergies and MS, a team of researchers analyzed 1,349 adults (344 men and 1,005 women) enrolled in the Comprehensive Longitudinal Investigation of Multiple Sclerosis at the Brigham and Women's Hospital (CLIMB) study.

Participants completed a self-administered questionnaire about environmental allergens such as pollen, grass, tree, dust, and pets; food allergies, including dairy, eggs, soy, shellfish, and nuts; and drug allergies. They also answered questions about the specific allergen and whether the allergy was confirmed by a physician.

Allergy symptoms were documented and included hives, itching, nasal congestion, rashes, watery or red eyes, tingling or itching in the mouth, swelling, trouble breathing, abdominal pain, diarrhea, nausea, vomiting, dizziness, or anaphylaxis.

Researchers then divided patients into one of four allergy groups: environmental, food, drugs, and no known allergies. They also rated the participants’ disease severity and conducted MRI scans to detect the presence and number of active lesions, or areas of inflammation in the brain.

Food Allergies Linked to More Relapses, Active Lesions

Participants with any type of allergy had a 1.22 times higher rate of relapse than the no-allergy group. Those with food allergies had a 1.4 times higher rate of relapse than those with no known allergies. They also were twice as likely to have active lesions on MRI.

In contrast, no significant differences were found between the no-allergy group and either the environmental or drug allergy groups.

Study Limitations

The researchers noted that the findings do not prove that allergies cause MS. The study relied on self-reported allergies unconfirmed by an allergy specialist, which are subjective. Furthermore, the questionnaire did not differentiate between true food allergy and adverse reactions to food such as indigestion. Also, the study did not provide any information regarding participants’ MS treatments.

Unknown Mechanism

"Food allergies could lead to an increase in MS inflammatory activity in adults through a variety of mechanisms," the researchers wrote, but the role of these mechanisms is not clear yet.

More research is needed to confirm the findings and understand the mechanisms behind the link, which could lead to new therapeutic and preventive strategies for MS.