With allergy season on its way, those of us who have hay fever will be stocking up on tissues, eye-drops and medicines, ready to combat the sneezes and itchy eyes. Allergies like hay fever occur when the immune response in the body becomes hypersensitive to a certain substance or allergen. In the example of hay fever, the allergen is grass and tree pollen, while other common allergens include dust mites, insect bites or stings, certain medicines and some types of food such as nuts, shellfish and milk.
Multiple Sclerosis (MS) is caused by something going wrong in the immune system too. This time it’s when the immune systems starts to attack the protective layer around the body’s own nerve cells.
So, could this mean there is a connection between allergies and Multiple Sclerosis (MS)?
What the science says:
Just because both conditions are related to the immune system this doesn’t automatically mean there is a connection, and research to date has provided mixed evidence on whether there is an association between allergies and MS. Some past studies have found no link at all while others have shown that allergies could even protect against MS.
It’s fair to say that looking back at previous research into this topic can feel a little confusing, but a paper published online in the Journal of Neurology, Neurosurgery & Psychiatry in December 2018, aimed to shed some light on MS and allergies.
In a study of 1,349 adults with MS, participants completed a questionnaire on any allergies they had and they were then categorized into groups according to whether they had an environmental allergy, a food allergy, a drug allergy or no known allergy. This was then matched up to their clinical data including MRI scans showing disease activity (lesions), the number of relapses they had experienced, their disability levels and their MS Severity Score (a measure used to compare disease progression rates between patients).
The results are in…
There was no solid evidence to show that allergies in general were associated with MS relapses but the results did show that having any of the allergies was associated with a higher chance of having active disease, shown through analysis of participants’ last MRI scan.
When it came to food allergies specifically, the researchers found that the rate of disease flare-ups in participants who had a food allergy was 27 percent higher than participants with no known food allergy. Not only that but having a food allergy was also associated with having twice the chance of showing active disease at the last clinic visit when compared to those with no known allergy.
Figuring out the why…
The results of this research imply that there is a connection between food allergy and MS, and the potential cause for this comes back to the root of both MS and allergies: the immune system. The researchers from this study demonstrated that it was possible that food allergies might boost the damaging immune response that is already occurring in people with MS, thereby worsening the symptoms. The other theory the researchers proposed was that food allergies may be having an impact on the bacteria in the gut which could in turn be producing chemicals that affect the central nervous system and that somehow this leads to the worsening of MS.
…and the when
All this sounds very promising, but don’t rush to the doctor or nutritionist for allergy tests based on this research quite yet. This is what’s called an observational study which means that while a potential connection, or correlation, has been seen between MS and food allergies, we can’t yet be sure that one is actually causing the other. More research in this area will help clarify the connection.
So, for now, this research is something to keep an eye on. (Although if your eyes are sore from hay fever, a trip to the doctors or pharmacy might be in order anyway… and perhaps the local store for some more tissues… Gesundheit!)