A study has found that patients with multiple sclerosis who have food allergies had more relapses and a higher likelihood of gadolinium-enhancing lesions than patients with no known allergy.
While the cause of multiple sclerosis (MS) remains unknown, published studies have shown that both genetic and environmental factors appear to contribute to disease risk and influence the course of MS. Established MS-associated risk factors include female sex, smoking, low vitamin D levels, infection with the Epstein–Barr virus, and obesity during adolescence. Furthermore, clinical research has identified several lifestyle and environmental factors that appear to trigger and exacerbate MS, some of which can affect the immune system.
A Comprehensive Analysis
Several epidemiological studies have investigated the connection between allergy and the risk and disease course of MS, but these investigations have yielded mixed results. For a study published in the Journal of Neurology, Neurosurgery & Psychiatry, Tanuja Chitnis, MD, and colleagues sought to clarify the possible association. They assessed more than 1,300 adults with clinical MS and MRI-confirmed disease activity who had a self-reported history of allergic conditions. Participants were a subset of patients who were enrolled in the Comprehensive Longitudinal Investigation of Multiple Sclerosis at Brigham and Women’s Hospital (CLIMB).
“Patients from the CLIMB study completed a one-time allergy-exposure questionnaire on food and drug allergies,” explains Dr. Chitnis. “We assessed the frequency of allergy, and subtyped patients by allergy type. Patients were categorized as environmental (pollen, grass, etc), food allergy, or drug allergy. Those with none of these allergies were classified into the no allergy group. We then assessed the MS relapse rates in the allergy groups and compared them with patients in the no allergy group.” Clinical and radiological variables and their associations with the different allergy groups were evaluated as part of the analysis. MS disease activity was assessed by evaluating the cumulative number of attacks over the disease course and by new gadolinium-enhancing lesions that were detected by MRI.
“Overall, we found that patients with MS who had food allergies had a 38% increase in allergies when compared with the no allergy group, even after we controlled for appropriate covariates,” Dr. Chitnis says. Patients with food allergy had a 1.3 times significantly higher rate for cumulative number of attacks when compared with patients with no allergies (Table). This observed effect remained significant even after adjusting for possible confounders like sex, age at symptom onset, and disease category.
In addition, Dr. Chitnis says patients with food allergies demonstrated a 2.5 times higher likelihood of having a gadolinium-enhancing lesion on their brain MRI. In this regard, the environmental allergy and drug allergy groups did not exhibit major differences when compared with the group that had no reported allergies.
Examining the Implications
The effects of allergy on the disease course of MS may have important biological and therapeutic implications. Dr. Chitnis suggests that the association between food allergy and MS disease activity highlights an important role for the gut, which has been shown to have an impact in immunity and inflammation. “Our findings point to a role of food allergy in the causation of new relapse activity in patients with MS,” she says. “Our findings indicate that food allergies may trigger or exacerbate immune mechanisms related to the gut, which in turn increase the risk of MS relapses.”
While the findings currently have limited clinical actionability, there is optimism about the potential translational significance of this research. This research opens a new way of thinking about the immune mechanisms in MS. “We are currently conducting studies to confirm findings from our investigation and to better understand the underlying biological mechanisms of MS by analyzing blood biomarkers of allergy,” says Dr. Chitnis. These insights could lead to new therapeutic and preventative strategies for MS, according to the study. In the meantime, Dr. Chitnis recommends clinicians counsel their patients with MS who have food allergies on preventing or reducing exposures to offending foods.