Whether caffeine improves or exacerbates headaches is still a matter of debate—it can be a headache trigger, but it can also provide pain relief. A new study out of Norway seems only to muddy the waters even more.

Scandinavians are heavy coffee drinkers, averaging four cups of coffee a day, which concerned Norwegian researchers. In an attempt to clear up the confusion regarding caffeine, they gave a questionnaire to over 50,000 people. Their findings: people who drink large amounts of caffeine each day (500 mg or more) are 18% more likely to suffer occasional headaches than those who drink around 125 mg per day. But, in a finding that had “no obvious reason” according to the researchers, people with moderate-to-low caffeine consumption were more likely to have chronic headache.

While the study highlights trends, it cannot determine cause and effect, the researchers noted. In other words, they could not conclude whether caffeine actually causes headaches or why chronic headache was more prevalent amongst people who drank less caffeine. Nevertheless, lead researcher Knut Hagen said, “People who suffer from headaches should be focused on their caffeine use, because it can be a cause of their headaches.”

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