Ever wonder why you can’t get through the day without your two cups of java, but your spouse and college-age daughter shun the brew? (Okay, I have.) A new study led by Harvard School of Public Health and Brigham and Women’s Hospital researchers found genes may be at least partly to blame -- and not necessarily those that govern our taste buds.
In a giant analysis of 120,000 regular coffee drinkers from dozens of studies, scientists identified six new gene variations linked to coffee and caffeine consumption. The finding, published Tuesday in the journal Molecular Psychiatry, could explain why a small Starbucks latte makes one person nauseous and jittery, while another feels charged and energized.
It may also account for some of the growing list of health benefits -- and a few of the detrimental effects -- that have been associated with coffee consumption.
Two of the gene variations were identified near genes BDNF and SLC6A4, which are thought to play a role in the rewarding effects of caffeine; the other variations were near genes involved in glucose and fat metabolism, blood pressure regulation, and addiction. Coffee drinkers had an increased likelihood of having high blood sugar levels and high cholesterol, but were less likely to have high blood pressure than those who abstained from the beverage.
“The genes we identified were predominantly related to caffeine and its metabolism or effects elicited by caffeine,” said study leader Marilyn Cornelis, research associate in the Department of Nutrition at Harvard School of Public Health. “We didn’t find gene variants related to taste.”
People who metabolize caffeine more quickly are more likely to drink more coffee. “They lose the effect of coffee quickly, which drives them to have more,” she explained. One of the gene variations linked to coffee is also tied to smoking initiation and obesity, both of which may be driven by addiction.
Study participants who inherited five or six of the gene variations were slightly more likely to be heavy coffee drinkers, consuming four or more cups a day, than those who had just one or two of the variations.
Cornelis emphasized that other genes are involved in determining our coffee preferences. A 2011 study she led found two other gene variations that play an even stronger role in determining how much caffeine we consume.
The next step for the researchers? Cull through the latest headline-grabbing coffee findings -- like this one linking coffee to an increased life span and this one linking coffee to an earlier death -- to determine whether genes associated with coffee consumption are having an impact on health.
“We’ve been bombarded with studies showing good and bad findings related to coffee,” Cornelis said, “but genes may account for these health differences among people that also lead some to drink coffee and others to abstain.”