High coffee consumption decreased the odds of developing multiple sclerosis (MS) in two separate case-control studies conducted by Dr. Anna K. Hedström of the Karolinska Institute, Stockholm, and her associates.
The investigators analyzed coffee consumption across certain ages among 1,620 cases and 2,788 controls in the Swedish Epidemiological Investigation of Multiple Sclerosis (EIMS) and 1,159 cases and 1,172 controls in the Kaiser Permanente Medical Care Plan, Northern California Region (KPNC).
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In EIMS, the adjusted odds ratio (OR) was 0.70 (95% confidence interval, 0.49-0.99; P = .04) among participants who drank six or more cups of coffee (greater than 900 mL) daily at the index year, which was defined as the year of the initial appearance of symptoms indicative of MS. The corresponding OR for those who reported high coffee consumption at 5 and 10 years before the study was 0.72 and 0.71, respectively, but neither comparison reached statistical significance.
In KPNC, those who consumed four or more cups of coffee (more than 948 mL in this study) daily were significantly less likely to develop MS than were those who never drank coffee (OR, 0.69; 95% CI, 0.50-0.96; P = .05). And the cohorts who drank four or more cups of coffee daily at least 5 years prior to the study were associated with significantly reduced odds of MS (OR, 0.64).
The combined results of the two studies in a meta-analysis found a significant, 29% reduction in the likelihood of developing MS among the highest drinkers of coffee (greater than 900 mL daily in EIMS and greater than 948 mL in KPNC). The investigators adjusted all the analyses for many demographic and environmental risk factors for MS, including age, gender, residential area, ancestry, smoking habits, exposure to passive smoking, sun exposure habits, and body mass index at age 20 years.
No evidence was found for associations between increased amounts of tea or soda intake and 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,” the researchers concluded.
Find the full study in the Journal of Neurology, Neurosurgery & Psychiatry (doi: 10.1136/jnnp-2015-312176).