High Daily Coffee Consumption Linked to Lower MS Risk

March 10, 2016

High consumption of coffee, amounting to more than six cups per day, is associated with a reduced risk of developing multiple sclerosis (MS) in two new case-control studies.

The studies, reported together in paper published online in the Journal of Neurology Neurosurgery & Psychiatry on March 3, were conducted by a team led by A.K. Hedström, MD, Karolinska Institutet, Stockholm, Sweden.

The authors point out that these results are in line with similar observations in studies in animal models of MS and that coffee and caffeine have both been associated with a reduced risk for Parkinson's disease.

The case-control studies were conducted in Sweden and California. The Swedish study included 1620 adults with MS (case-patients) and a comparison group of 2788 persons matched for age and sex (controls); the California study included 1159 patients with MS (case-patients) and 1172 healthy matched controls.

In both studies, participants were asked about their coffee intake across different time periods.

Results showed that the risk for MS was consistently higher among those drinking fewer cups of coffee every day in both studies, even after adjustment for confounders, such as smoking and weight during the teenage years.

In the Swedish study, drinking more than six cups of coffee each day was associated with a 30% lower risk for MS (odds ratio, 0.70; 95% confidence interval [CI], 0.49 - 0.99).

In the California study, those who drank more than 948 mL of coffee daily had a 31% lower risk for MS compared with those who never drank coffee (odds ratio, 0.69; 95% CI, 0.50 - 0.96).

Lower odds of MS with increasing consumption of coffee were observed regardless of whether coffee consumption at disease onset or 5 or 10 years before disease onset was considered.

The researchers suggest possible mechanisms that may explain their results, including observations from experimental studies that caffeine upregulates adenosine 1A receptors (which protects against experimental autoimmune encephalomyelitis and reduces proinflammatory cytokine production).

They caution that the current studies were observational, so no firm conclusions can be drawn about cause and effect; that changes in coffee consumption between MS diagnosis and data collection could have influenced the results; and that recall of coffee consumption could have been inaccurate.

But they also note that the studies have several strengths, including recruitment of case-patients and controls from the same reference population and adjustment of the results for many potential confounding factors, including currently established environmental risk factors for MS.

"Further studies are required to establish if it is in fact caffeine, or if there is another molecule in coffee underlying the findings, to longitudinally assess the association between consumption of coffee and disease activity in MS, and to evaluate the mechanisms by which coffee may be acting, which could thus lead to new therapeutic targets," they conclude.

"Growing Evidence" for Health Effects of Coffee

In an accompanying editorial, José Maria Andreas Wijnands, PhD, and Elaine Kingwell, PhD, University of British Columbia, Vancouver, Canada, call the findings "intriguing."

"Although it remains to be shown whether drinking coffee can prevent the development of MS, the results of these thorough analyses add to the growing evidence for the beneficial health effects of coffee," they write.

"The intriguing findings indicate that the role of coffee in the development of MS clearly warrants further investigation, as do the mechanisms that underlie the relationship."

In their editorial, Dr Wijnands and Dr Kingwell say the current study is notable for its particularly large international sample of 2779 patients with MS and access to detailed information on several important potential confounders.

They add that the authors were able to show that while smoking is a clear confounder and has an important attenuating influence, the association between high coffee consumption and reduced risk for MS was evident in people with and without a history of smoking.

They note that other case-control studies have not found a link between coffee consumption and MS risk but that: "Given the well-known challenges that exist in untangling the nature of associations between dietary factors and disease risk, these inconsistencies are perhaps not surprising."

The work was supported by grants from the Swedish Research Council; the Swedish Research Council for Health, Working Life and Welfare; the Knut and Alice Wallenberg Foundation; the AFA Foundation; the Swedish Brain Foundation; the Swedish Association for Persons with Neurological Disabilities; the National Institutes of Health (NIH)/National Institute of Neurologic Disorders and Stroke; the NIH/National Institute of Environmental and Health Sciences; and the NIH/National Institute on Allergy and Infectious Diseases. Dr Hedström has disclosed no relevant financial relationships; disclosures for coauthors appear in the paper. Dr Wijnands and Dr Kingwell have disclosed no relevant financial relationships.

J Neurol Neurosurg Psychiatry. Published online March 3, 2016. Full text Editorial

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