Should You Be Drinking More Or Less Coffee?

A new meta-analysis from the Harvard School of Public Health and Brigham and Women’s Hospital finds that genetics play a role in why caffeine affects people in different ways.

In the study, researchers performed a genome-wide meta-analysis of more than 120,000 regular coffee drinkers, studying Americans of either European or African ancestry. The investigators identified 2 gene variants—POR and ABCG2—connected to caffeine metabolism, as well as pinpointing 2 gene variants near BDNF and SLC6AF that may affect the rewarding impact of caffeine. For the first time, 2 genes involved in glucose and lipid metabolism—GCKR and MLXIPL—were also associated with the metabolic and neurological effects of caffeine.
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While caffeine and coffee have previously been linked to beneficial and adverse health effects, these findings may enable subgroups of individuals most likely to gain from raising or lowering coffee consumption to be identified, according to the authors.

Nevertheless, “how coffee impacts health is not completely clear,” says Marilyn Cornelis, a research associate in the department of nutrition at the Harvard School of Public Health, and lead author of the study.

Evidence as to the beneficial effects of coffee is mounting, says Cornelis, in contrast to health messages “delivered decades ago, which gave coffee a bad rap.

“We also know, however, that individuals differ in their response and tolerance to caffeine,” she continues. “And our findings suggest those differences have a genetic basis and are powerful enough to modulate our drinking behavior accordingly.

To date, these genetic factors “have not been accounted for in studies of coffee and health, so whether individuals with specific genotypes are impacted to the same degree as other individuals with a different genotype is an open question. These are the types of studies we will pursue in the future.”

Only when these studies have been performed can physicians provide personalized guidance on coffee consumption for optimal health, says Cornelis.

“At this stage, I think it is more important that physicians at least recognize that a given amount of coffee can have very different effects on different individuals, and this may be due to genetics—identified in the current study or yet to be identified—or other factors,” she concludes.

“For example, a patient who consumes 4 cups a day and another consuming 1 cup per day may very well experience the same risks or benefits linked to coffee as a result of his or her different genotypes. ‘One-size fits all’ advice would not be appropriate in this particular scenario.”

—Mark McGraw

Reference

Cornelis M, et al. Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption. Mol Psychiatry. 2014.