A new research study published online in the Journal of Neurology, Neurosurgery & Psychiatry suggests that drinking six cups of coffee a day could lower the risk of developing multiple sclerosis (MS). The researchers said the neuroprotective and anti-inflammatory properties of caffeine in coffee may explain why drinking a lot of coffee every day — more than 30 ounces, or around six cups — has been linked to a reduced risk of MS.
The article, “High consumption of coffee has been associated with decreased multiple sclerosis risk in the findings of two independent studies,“ is authored by Dr. A. K. Hedström and a team of colleagues at the Karolinska Institutet, Institute of Environmental Medicine in Stockholm, Sweden; Johns Hopkins University in Baltimore, Maryland; the School of Public Health Genetic Epidemiology and Genomics Lab at the University of California, Berkeley; the Kaiser Permanente Division of Research in Oakland, California; and the Department of Clinical Neuroscience and Center for Molecular Medicine at the Karolinska Institutet at Karolinska University Hospital in Solna, Sweden.
The researchers noted that previous studies on the relationship between caffeine consumption and MS risk had yielded inconclusive results; therefore, their objective was to investigate whether consumption of coffee really is associated with a reduced risk of MS.
The team collected retrospective data from two population-representative case control studies that monitored participants with different coffee consumption habits: a Swedish study of 1,620 MS cases and 2,788 controls matched for age and sex, and a U.S. study comprising 1,159 cases and 1,172 controls.
In both studies, participants were asked to describe their coffee drinking habits and histories. The collected data was compared regarding risk of MS after adjusting for “a broad range of potential confounding factors.”
The researchers estimated coffee consumption at and before the start of MS symptoms in persons with the disease and compared it with that in the healthy groups. The results showed that the MS risk was consistently higher among those drinking fewer cups of coffee every day in both studies, even after accounting for other potentially important contributing factors, such as smoking and weight during teenage years.
The Swedish study found coffee consumption to be associated with reduced MS risk both at onset of symptoms and five and 10 years beforehand, with a 28-30 percent lower risk among those drinking more than six cups (at least 30 ounces) a day. Similar results were observed in the U.S. study, which determined a 26-31 percent lower MS risk among peeple drinking more than 30 ounces a day at least five years beforehand and at the start of symptoms, compared with those who never drank coffee.
The researchers also found a correlation between the quantity of coffee and a lower MS risk, although because this was an observational study, no firm conclusions can be drawn about cause and effect.
Based on their findings, and in accordance with studies in animal models of MS, the investigators concluded that high consumption of coffee may decrease the risk of developing MS, noting that caffeine, in addition to being a central nervous system stimulant, has known neuroprotective properties, and has been shown to suppress the production of pro-inflammatory cytokines — chemicals involved in the inflammatory response — which they suggest may be the mechanisms underlying the association.
However, researchers caution that further investigation is needed to determine whether exposure to caffeine is actually the agent underlying that association, and if so, to scientifically evaluate its mechanisms of action.
In an editorial commentary on the study, entitled “Time to wake up and smell the coffee? Coffee consumption and multiple sclerosis,“ José Maria Andreas Wijnants and Elaine Kingwell of the University of British Columbia in Vancouver, Canada, noted that with a global consumption estimated at 2.25 billion cups per day, coffee is one of the most popular beverages worldwide, with one likely reason for its popularity being its caffeine content, which can increase attention and alertness.
However, Wijnands and Kingwell observed that in addition to its short-term effects on mental performance, an increasing body of evidence suggests coffee may have long-term health benefits as well, including protection against neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. However, the effects of drinking coffee in MS prevention remain relatively unexplored.
The editorialists further observed that the study is notable for being based on a particularly large international sample of 2,779 MS cases, and providing access to detailed information on several important potential confounding factors. Moreover, the study’s authors were able to show that while smoking is a clear confounder, exerting a significant attenuating influence, negative association between high coffee consumption and MS is evident in people both with and without a history of smoking.
Wijnands and Kingwell also observed that despite considering multiple potential confounding factors, it was impossible for the researchers to control for all possible factors, and coffee drinking may be associated with other health and lifestyle-related factors, including the intake of dietary elements that are more difficult to measure and capture.
Nevertheless, Wijnands and Kingwell concluded that although it remains to be proven conclusively that drinking coffee can prevent the development of MS, the results of these analyses add to the growing evidence supporting the beneficial health effects of coffee consumption, and that the studies’ findings linking coffee to MS warrants further investigation. This could potentially contribute to a better understanding of MS etiology and lead to development of novel MS therapies.
For more information, see the American Heart Association journal Circulation study, “Association of Coffee Consumption With Total and Cause-Specific Mortality in 3 Large Prospective Cohorts.“