Some individuals report reactions to chocolate that are not classified as allergies. These reactions, including migraine headaches, may be exacerbated by genetics, lifestyle, medications and hormones.
Migraines, in particular, have long been associated with chocolate consumption, particularly among women. One study of 490 persons with migraines found that 19 percent reported they thought chocolate caused their headaches. Other research demonstrates a lack of relationship between chocolate and headache. Moffet, Swash and Scott studied a group of 25 migraine sufferers, giving them a chocolate sample and a placebo (carob) two weeks apart. The subjects completed questionnaires regarding their reactions within 48 hours of sample consumption. There was no difference in headache occurrence after either sample. In a second study, the researchers repeated the same procedure with 15 of the 25 subjects and again found no difference in reported headaches after either sample.
In a recent study, Pittsburgh State University researchers demonstrated a lack of relationship between chocolate and headache in a large sample of women with migraine or tension-type headaches. After following a vasoactive-amine elimination diet, 63 subjects ingested two 60g chocolate samples and two 60g carob samples in random order on four different occasions. Results indicated that chocolate was no more likely to trigger a headache than carob, even in subjects who strongly believed chocolate was a trigger food. The subjects also were unsuccessful at guessing which samples were chocolate during the trials. The researchers conducted a separate evaluation on 17 percent of the study's subjects who identified themselves as sensitive to chocolate as a headache trigger. Ingestion of chocolate samples did not result in headaches.
The reason that chocolate is frequently cited as a food trigger by migraine sufferers despite evidence to the contrary may lie in other aspects of chocolate. Women are three times more likely than men to suffer from migraines and women also crave chocolate more frequently than men, but this does not prove a cause-effect relationship. Sweet craving itself has been reported as a prodromal symptom of migraine, suggesting that chocolate craving and consumption may be a symptom rather than a cause of migraine. Other factors, including fluctuating estrogen levels associated with the onset of menses have been clearly associated with the onset of migraines.
* Bibliography of scientific journals referenced here available upon request.