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SAN FRANCISCO -- Chocolate and other foods commonly thought to trigger migraine were found to have little relationship to headache onset when patients kept systematic track, according to several studies presented here.

Study participants used a web interface or smartphone app to record their food consumption and timing of headaches, allowing researchers to analyze patterns of association. One analysis looked at headache occurrence on weekdays versus weekends.

These findings were presented at the American Headache Society (AHS) annual meeting. The conference also featured an expert debate about whether people prone to migraine should always avoid potential triggers.

A wide range of factors are thought to trigger migraine headache. Some, such as stress, lack of sleep, and hormonal fluctuations, are supported by considerable evidence. Others, such as specific food items, are more anecdotal and research has yielded mixed results. Digital tools that make it easier for patients to record their experience can help shed light on suspected associations.

"We know that migraine and its triggers differ for every person," said AHS scientific program committee chair Peter Goadsby, MD, PhD, of King's College London. "These data will hopefully help healthcare providers when evaluating the lifestyle and experiential factors of an individual patient's life."

Chocolate and Other Triggers

Stephen Donoghue, PhD, of , formerly known as Curelator Headache, and colleagues presented a series of posters describing studies looking at the links between suspected triggers and migraine occurrence.

Patients with migraine used the Curelator Headache digital platform, available through a web interface or an iPhone app, to answer questions about more than 70 migraine-related factors. A total of 774 people tracked these factors and the occurrence of headaches daily for at least 90 days. More than 80% were women and the mean age was 43 years.

Just over half of the participants (53.7%) said that chocolate was a suspected trigger, with 27.0% saying it had a mild effect (1-3 on a 10-point scale), 14.6% rating it had a moderate effect (4-6), and 12.0% saying it was a strong factor (7-10); 46.3% said they did not suspect chocolate as a trigger.

Among the 606 participants who entered enough data for analysis, chocolate was found to be associated with an increased risk of headache attacks for 10 people (1.7%) and a decreased risk for 16 people (2.6%), with no association noted for the remaining 580 people (95.7%).

About one in five participants did not enter enough data, reported too little or insufficient variability in their chocolate consumption, or had too few or too many migraine attacks to allow for reliable analysis.

"Chocolate is certainly not a common trigger," the investigators concluded. "It is probable that the low levels of association for both increased and decreased attack risk are simply stochastic. Nevertheless, we cannot rule out that chocolate may be a trigger for some people and a protector for others -- but they would be the exception rather than the rule."

Results were generally similar for nitrates, used as a preservative for foods such as processed meats, and the food additive monosodium glutamate (MSG).

A total of 347 participants (47.5%) suspected nitrate as a migraine trigger, while 384 (52.5%) did not. Among the 370 people who entered enough data for analysis, nitrates were shown to be associated with increased headache risk for 10 people (2.7%), decreased risk for five people (1.4%), and no association was seen for 355 people (95.9%).

Likewise, 385 (52.6%) suspected MSG as a triggering factor, while 347 (47.4%) did not. Among the 227 people with analyzable data, MSG was found to be associated with increased risk for seven people (3.1%), decreased risk for two people (0.9%), and no association for 218 people (96.0%).

For both nitrates and MSG, more than half of study participants did not enter enough data or were not analyzable for various reasons.

For all three triggers, the researchers noted that there was no clear link between the degree of suspicion and the likelihood of identifying an association. Many people reported no consumption of chocolate, nitrates, or MSG, which the researchers suggested might indicate avoidance of a suspected trigger.

"Contrary to the widespread expectations of our users, the data reveals that foods containing chocolate, MSG, and nitrates are rarely associated with migraine attacks and surprisingly, for a minority of individuals, they may be associated with a lower risk of attack," N1-Headache founder and CEO Alec Mian, PhD, said in a company press release.

The investigators also looked at the association between type of day -- weekday or weekend -- and migraine occurrence. Among the 707 participants eligible for this analysis, 26 (3.7%) had an increased risk of headache attacks on non-work days, 10 (1.4%) had a decreased risk, and 623 (88.1%) had no identifiable association.

"The concept of 'weekend headache' is widely accepted among clinicians and patients, yet clinical trials to date have yielded conflicting results which neither confirm nor deny the presence of this headache pattern," the researchers concluded. "For almost all subjects in this study, the risk of migraine did not differ on work days compared to days off and holidays."

Triggers: To Avoid or Not to Avoid

During the debate on migraine triggers, Richard Lipton, MD, of Albert Einstein College of Medicine in New York City, took the "should avoid all triggers" position, noting that these can be highly variable across individuals.

His opponent, Paul Martin of Australian National University in Canberra, countered that there are so many purported migraine triggers, and they are so ubiquitous, that is futile to try to avoid them all at all times -- and trying to do so can actually increase anxiety. Instead, people with migraines should receive help to cope with triggers.

During a media briefing in advance of the meeting, Goadsby suggested a new way of thinking about migraine triggers.

"What we're learning by studying the premonitory phase that occurs in the days or hours before the attack, when the patient will feel tired or get a bit moody or crave sweet or savory things, is that the brain has actually started to have the attack," he told reporters. "Chocolate is an excellent example. When the brain drives you to take some chocolate and a day and a half later you get migraine, the association is absolutely correct, but the causality is different -- the mechanism has already started."

"What we're learning from the diary work is that while you can recommend general regularity, an individual needs to ask themselves whether what they're calling a trigger is actually the beginning of their attack. That releases them from the punishment of worrying about the trigger and gives them information about what is about to happen," Goadsby continued. "Obviously, if you feel you're in the premonitory phase that is not a night to go out, to stay up late, to find your favorite alcohol. It's a night to be careful, to look after yourself, to prepare for the next day. This understanding is going to empower patients to get better control."

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