Why do carbs give me headaches?

Q: Why do carbs and sugar give me headaches?

It’s common for people to notice a headache coming on after eating certain foods, and foods high in sugar or refined carbohydrates, like chocolate cake or pasta, are among the usual suspects. Such food triggers are often reported by people who have migraines, said Dr Peter Goadsby, a professor of neurology at King’s College London and the University of California, Los Angeles. “The person that’s asking this question, pounds to pennies, has migraine,” he said, particularly if certain foods seem to be repeat triggers.

Unlike the more common tension-type headaches most people get from time to time, migraines — which affect an estimated 18% of women and 6% of men each year in the United States — are much more debilitating, said Dr Rashmi Halker Singh, an associate professor of neurology and a headache medicine specialist at the Mayo Clinic in Scottsdale, Arizona.

In one review of studies published in 2018, researchers concluded that nearly 30% of patients reported that certain foods or eating habits triggered their headaches. But recent research by Goadsby and others suggests that it’s most likely not the foods that cause migraines, but rather it’s the migraines that cause people to eat certain foods.

In the initial stage of a migraine attack — the premonitory or prodrome phase, which can begin a few hours to days before the headache phase hits — people may experience symptoms like fatigue, brain fog, mood changes, light sensitivity, muscle stiffness, yawning and increased urination, Goadsby said.

During this time, brain imaging studies have shown that the hypothalamus, a region of the brain that regulates hunger, is activated, causing people to want certain foods. “It is pretty clear that this area is changing in its activity before the pain starts,” he said. Some people want savoury or salty snacks, while others crave sweets and chocolate.

Then, after they’ve indulged their craving and the headache phase of the migraine begins, it’s natural for people to wonder if something they ate contributed to the pain, Halker Singh said. “Sometimes people come in and tell me, ‘I had some chocolate, and soon after that, my migraine attack started,’” leading them to guess that the chocolate itself triggered the headache. But what also could have happened, she said, “is that maybe the craving for chocolate was actually the start of the migraine.”

Chocolate is among the most reported food triggers for migraines, but in one review of studies published in the journal Nutrients in 2020, researchers concluded that there wasn’t enough evidence to say that chocolate can cause migraines. In the above scenario, Goadsby said, the person would have probably gotten a headache whether they ate the chocolate or not. So if you’re craving a treat during the early stages of a headache, he said, it’s fine to enjoy it.

If you often get food cravings before migraine headaches, it’s still a good idea to take note of them, along with other prodrome phase symptoms, so you can prepare for what’s coming. You might use that time to find your migraine medication and opt for an early bedtime, he said.

Margaret Slavin, an associate professor of nutrition and food studies at George Mason University, said that foods high in sugar or refined carbohydrates can also cause blood sugar to spike, leading to “an outsized insulin response.” Insulin helps normalise blood sugar, but too much insulin can overshoot the goal, leading to low blood sugar. This condition is called reactive hypoglycemia, and a headache is one of its symptoms, along with feeling weak, shaky, tired and lightheaded.

For people who get migraines, it’s also possible that regularly following a diet high in refined sugar and processed carbohydrates might increase inflammation levels in their body and make them more susceptible to attacks, Slavin said. There is some limited research to support this idea, and it may be worth trying to cut back on added sugar in favour of anti-inflammatory foods like fruits, vegetables, nuts, beans, whole grains and fish.

Skipping meals and fasting are also commonly reported migraine triggers, so Halker Singh advises her patients to eat regular, nutritious meals, in addition to getting enough sleep, exercising regularly and managing stress.

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