Drinking four to six cups of coffee daily may lower the risk of developing multiple sclerosis (MS), a chronic disease that attacks the central nervous system - brain, spinal cord and optic nerves.
Caffeine intake has already been associated with a reduced risk of Parkinson's and Alzheimer's diseases.
"Our study shows that coffee intake may also protect against MS, supporting the idea that the drug may have protective effects for the brain," said study author Ellen Mowry from Johns Hopkins University's school of medicine in Baltimore.
For the study, researchers looked at a Swedish study of 1,629 people with MS and 2,807 healthy people, and a US study of 1,159 people with MS and 1,172 healthy people.
The studies characterised coffee consumption among persons with MS one and five years before MS symptoms began (as well as 10 years before MS symptoms began in the Swedish study) and compared it to coffee consumption of people who did not have MS at similar time periods.
The study also accounted for other factors such as age, sex, smoking, body mass index and sun exposure habits.
More From This Section
The Swedish study found that compared to people who drank at least six cups of coffee per day during the year before symptoms appeared, those who did not drink coffee had about a one and a half times increased risk of developing MS.
Drinking large amount of coffee five or 10 years before symptoms started was similarly protective.
In the US study, people who did not drink coffee were also about one and a half times more likely to develop the disease than those who drank four or more cups of coffee per day in the year before symptoms started to develop the disease.
"Caffeine should be studied for its impact on relapses and long-term disability in MS as well," Mowry pointed out.
The findings will be shared at the American Academy of Neurology's 67th annual meeting in Washington, DC, April 18-25.