— Case-control studies suggest coffee may protect against the risk of MS.
by Kristina Fiore, Staff Writer, MedPage Today February 26, 2015

Last Updated December 3, 2015

Filling up on coffee may protect against development of multiple sclerosis, according to findings from two cohort studies.

In both studies, patients with the highest levels of coffee consumption had significantly lower risks of developing MS over various time periods, Ellen Mowry, MD, of Johns Hopkins, and colleagues reported in an early-release abstract from this year’s American Academy of Neurology meeting.

The authors suspect that the caffeine in coffee is responsible for the relationship.

“Caffeine could be an attractive compound given its apparent benefit in protecting against Parkinson’s and Alzheimer’s diseases,” Mowry said in an email to MedPage Today. “The exact mechanism by which it does so in those diseases is unclear, and if caffeine is confirmed to be protective in MS, it may still be acting via a different mechanism.”

Although the balance of evidence linking coffee and Parkinson’s and Alzheimer’s falls on the side of benefit, the literature on coffee and MS is far less clear.

“The literature is a bit limited with respect to coffee and MS risk,” Mowry said. “One study showed no apparent association between the two, although notably that study had fewer patients than ours.”

She noted that her study was limited because it “asked patients about prior coffee intake after the diagnosis of MS was made, such that it is possible that ‘recall bias’ played a role. For example, perhaps patients with MS subconsciously underestimated their previous coffee intake more than people without MS.”

She and colleagues conducted two population-based, case-control studies. One was a Swedish study that included 1,629 MS cases and 2,087 controls. The other was a Kaiser Permanente Northern California study of 584 cases and 581 controls.

In the Swedish cohort, they found that drinking coffee was associated with a reduced odds of developing MS compared with drinking no coffee at all.

The reduction in risk was greatest for those who drank the most coffee. Those who reported having at least six cups a day or more had a 33% reduction in risk of developing MS compared with not drinking any coffee (OR 0.67, 95% CI 0.47 to 0.95).

The researchers also found that those who had high coffee consumption for either 5 or 10 years before the index year had a lower likelihood of developing MS:

• 5 years: OR 0.70, 95% CI 0.50-0.99
• 10 years: OR 0.72, 95% CI 0.48-1.06

Similar results were seen in the northern California study. People who drank at least four cups of coffee per day prior to the index year also had a 33% reduction in risk of MS compared with those who drank no coffee, they found (OR 0.67, 95% CI 0.47-0.95).

A possible explanation for the association is that the caffeine in the coffee has neuroprotective properties and may suppress the production of proinflammatory cytokines, the researchers said.

Although the relationship requires further study, Mowry said coffee and caffeine should also be studied for potential effects relapses and long-term disability in MS.

Lily Jung, MD, an MS expert in Seattle, who was not involved in the study, told MedPage Today that the “number of cases reviewed and the consistency of the odds ratio for the two populations certainly seems supportive of the theory, particularly with what we have seen in PD and AD.”

“That said,” she continued, “we obviously also need to have a better understanding of the potential health risks of drinking this much coffee. It would also be fascinating to figure out the mechanism for the benefit because if in fact we can prove that there is benefit, perhaps some therapeutic derivative could be determined that would offer neuroprotection without the side effects of such high coffee consumption. Obviously we need to see more study in this area.”