Can't Get Enough Coffee? It Might Be in Your Genes
By Meredith Melnick Friday, April 8, 2011 | 329 comments
FRANK ROTHE / PHOTONICA VIA GETTY IMAGES
If you rely on a deep, sludgy kick of java to get you through the day, your need for caffeine might have something to do with your genes: a team of researchers have identified variations on two genes that may influence how much coffee people consume.
The study was a meta-analysis of data from five studies involving 47,341 U.S. participants of European descent, and run by scientists from the National Cancer Institute, Harvard School of Public Health, Brigham and Women's Hospital, and the University of North Carolina at Chapel Hill.
The genes in question are known as CYP1A2, which is involved with the body's caffeine metabolism, and AHR, which regulates CYP1A2. Scientists found that people with high-consumption variants of either gene on both chromosomes consumed on average about 40 mg more caffeine per day than people who didn't have the mutation on either chromosome. (More on Time.com: Drinking Coffee May Lower Women's Risk of Stroke)
Forty milligrams is not a huge amount, equivalent to a can of soda or a third of a cup of coffee. The researchers measured all sources from which participants got caffeine, including soda, tea and chocolate, but about 80% came from coffee.
The authors acknowledge that the influence of these genes on caffeine intake is small, accounting for less than 1% of the variation in coffee consumption in the reviewed studies. But the results suggest that there may be many other genes that contribute to how much caffeine people consume, and may help researchers better understand the effects of the drug on the body. (More on Time.com: A Man Dies After Overdosing on Caffeine)
The Boston Globe's Daily Dose blog reported:
What's interesting, though, is that mutations studied were involved with how fast the body metabolizes caffeine as well as certain chemicals and toxic substances. And it could be that those who metabolize caffeine faster are more likely to be looking quickly for their next hit of coffee than those who are slow metabolizers, [study co-author and professor of computational biology at Brigham and Women's Hospital Daniel] Chasman speculates.
And — if you want to take these theories one step beyond — these gene mutations that predispose some to a higher caffeine intake might also protect them from dangerous toxins by flushing them more quickly out of the body. And that could provide some explanation for why coffee drinkers have been found in the latest research to have fewer health problems like strokes.
The study was published this week in PLoS Genetics.