Almost everyone gets a tension headache from time to time, but migraine headaches are a different matter, and can be quite severe and seriously interfere with normal life. About 10% of people suffer from migraine, and despite a huge amount of research around the world, we still only have a limited picture of the overall cause or what triggers a single episode.
There have been many speculative articles and personal anecdotes in the popular media about a possible role of gluten in triggering migraine. So, I decided to explore this controversy by looking at some of the available research studies.
Gluten causes a wide range of symptoms in the nervous system
Gluten is the only known trigger for celiac disease, which typically involves inflammation of the intestine. It’s also becoming increasingly clear that celiac disease can also have a wide range of neurological effects in the brain and the rest of the body (Ref. 1, Ref. 2). This leads to three questions regarding a migraine-celiac link:
- Are celiacs more likely to have migraines than the general public?
- Are people with migraines more likely to have celiac disease?
- Does gluten cause migraines?
We are getting closer to answers, but some of the evidence is contradictory.
Are celiacs more likely to have migraines?
In a 2001 study of 86 Spanish children with celiac disease, 19% had migraine headaches (Ref. 3), which is substantially higher than the approximately 10% value found in the general public. Interestingly, all the patients were already on a gluten-free diet to treat their celiac disease.
A German study of older celiac patients (mean age of 51) found migraine in 28% of them (Ref. 4). Again, the patients were on a gluten-free diet. One possible complication was that all the patients were volunteers, so we can’t be certain that they represent the celiac population in general.
Finally, in an Israeli study of 111 pediatric celiac disease patients, 14 (12.6%) were found to have migraine, compared to 5.7% in a similar population of non-celiac control subjects (Ref. 2)
Are people with migraines more likely to have celiac disease?
In a 2003 Italian study of 90 migraine patients, 4 were found to also have celiac disease. This frequency (4.4%) was significantly higher than the frequency of celiac disease in a randomly-selected control group of people without migraine headache (0.4%) (Ref. 5). For comparison, the overall prevalence of celiac disease in the general population is thought to be approximately 1%.
In one Turkish study, 73 children with migraine were tested for anti-TG2 antibodies (a strong indicator of the presence of celiac disease) (Ref. 6). Four patients (5.5%) were antibody-positive, compared to 0.6% of a group of 147 control children. Surprisingly, no evidence for actual celiac disease was found after an intestinal biopsy. Perhaps the antibody test may have uncovered a mild or early stage of the disease?
In contrast, a 2011 study of 100 Iranian children found a prevalence of celiac disease of only 2%, which was no different from the prevalence found in 1,500 control children without migraine headache (Ref. 7).
Does gluten cause migraines?
Even if there might be a slight association between these two diseases, this does not mean that the trigger for celiac disease (gluten) is the same as the trigger for migraine. Many diseases show up in clusters: for example, many people have both diabetes and high blood pressure, but this does not mean that diabetes is caused by hypertension, or vice versa. Many patients with celiac disease also have other autoimmune diseases such as diabetes, but there is no clear evidence that one causes the other.
As mentioned previously, two studies in patients whose celiac disease was well-controlled by a gluten-free diet still had a relatively high frequency of migraine. This doesn’t support the idea that gluten is a trigger for migraine (Ref. 3, Ref. 4).
In contrast, in one small study (Ref. 5), four newly-diagnosed celiacs with migraine were followed for 6 months after moving to a gluten-free diet. In this case, one had complete relief from migraine, while the other three showed an improvement in their symptoms. This migraine relief was accompanied by an improvement in blood flow to the brain in a PET scan.
Likewise, in one preliminary study of 14 patients (Ref. 2), migraine was found to be completely or partially relieved after shifting to a gluten-free diet.
It should be stressed that none of these studies was designed to rigorously test the potential role of gluten, while ruling out other possible unrelated effects.
What about non-celiac gluten sensitivity?
“Non-celiac gluten sensitivity” is less well-defined than celiac disease, but we are gradually reaching a consensus on diagnosis of gluten sensitivity. This field is still in flux, but many researchers now believe that this is a distinct condition. Briefly, if wheat allergy has been ruled out, and celiac disease has been ruled out, and the individual has symptoms which appear to be relieved after moving to a gluten-free diet, then the person is considered to be “gluten sensitive”. Very little is known about this condition, but it will be interesting to see how prevalent migraine is in this group, and whether gluten plays a role.
Scientific and ethical challenges in studying the health effects of gluten
Comparing a “gluten-free diet” with a “normal diet” is not really a rigorous test, because there are are many differences in food composition between these two diets, not just the presence or absence gluten. A preferred trial might be one in which everyone starts out on a gluten-free diet, and then testing the effect of adding back a known amount of gluten (or a placebo). Ideally, neither the patient nor clinician should be aware of who was receiving the trigger substance (a placebo-controlled, double-blind trial). No such trial has been performed yet, so any weak association with gluten is still very tentative.
Ethical problems arise when performing clinical trials on celiacs, because deliberately administering gluten to a patient with celiac disease will almost certainly cause intestinal damage, and healing can be slow. In contrast, trials studying the effect of diet on people with gluten sensitivity or migraine should be easier to accomplish.
Conclusion: The current evidence suggesting that gluten causes migraine headache is very tentative
While the studies so far suggest that there may be an association between celiac disease and migraine, we still do not have enough data to draw a firm conclusion that one causes the other. In addition, the evidence for the benefits of an elimination diet are weak, at best.
Once they have been diagnosed, most celiacs, of course, go on a gluten-free diet (or should); so, if anything, if gluten were an important trigger for their migraine, then celiacs might actually have a lower incidence of migraine than the general public! There is certainly no evidence for this.
While there have been many speculative articles in newspapers and on the internet that gluten is a trigger for migraine, the actual research results so far are much more tentative, and it is too early to conclude that a gluten-free diet will be helpful. This field is still in its infancy, and much larger, well-controlled clinical trials will be required before we can draw firm conclusions.
Ref. 1: Hadjivassiliou, et al. Gluten sensitivity: from gut to brain. Lancet Neurol (2010) 9:318-330.
Ref. 2: Zelnik, et al. Range of neurological disorders in patients with celiac disease. Pediatrics (2004) 113:1672-1676.
Ref. 3: Roche-Herrero, et al. The prevalence of headache in a population of patients with coeliac disease. Rev Neurol (2001) 32:301-309.
Ref. 4: Burk, et al. Neurological symptoms in patients with biopsy proven celiac disease. Mov Disord (2009) 16:2358-2362.
Ref. 5: Gabrielli, et al. Association between migraine and Celiac disease: results from a preliminary case-control and therapeutic study. Am J Gastroenterol (2003) 98:625-629.
Ref. 6: Alehan, et al. Increased risk for coeliac disease in paediatric patients with migraine. Cephalagia (2008) 28:945-949.