Caffeine: Could Be Your Genes
Ilike a cup of coffee in the morning. Especially after I load it up with sugar and milk. But my routine is more
hobby than habit; I’ve never come to rely
on a daily caffeine jolt. In fact, if I didn’t
have to stump off to work every morning,
I could finish my coffee and immediately
head back to bed.
But I know plenty of peo-
ple who can’t get through the
day without a steady supply of
coffee, or tea, or soda or
chocolate. They need the
buzz, and they don’t want the
Now researchers from Car-
olina, Harvard and five other
institutions may have found out
why some of us crave caffeine in
great quantities while others get
by on little or none. Habitual
caffeine consumption, says UNC
epidemiologist Keri Monda ’06
(PhD), could be in your genes.
Monda and her colleagues
analyzed the caffeine intake of
some 47,000 people. Each per-
son had filled out detailed
questionnaires for years about
the things they ate and drank, and each
had given a DNA sample. The researchers
looked at the entries for caffeinated coffee
and tea and caffeinated sodas and choco-
late and compared the results with the
participants’ genetic profiles.
the most widely
in the world.
percent of us
eat or drink
it every day.
some $40 billion
on coffee every
Two genes jumped out at the
researchers as having clear associations
with habitual caffeine consumption.
They’re called CYP1A2 and AHR. We
all have them. One of their functions is to
influence how our bodies metabolize caffeine and, possibly, the amounts each of us
crave and consume. People with certain
variations of the genes tend to consume
more caffeine, more often. It could be that
people who have the higher-caffeine-con-sumption genotype metabolize caffeine at
a faster rate than others, Monda says,
although their study didn’t extend to specific biologic functions. That may mean
some of us need more caffeine to get or
maintain the buzz, or even just to keep
the withdrawal symptoms at bay.
Harvard’s Marilyn Cornelis, the lead
researcher on the study, says her father
drinks at least 10 cups of coffee a day.
“He’s not trying to achieve pleasurable
effects,” she told WebMD. “Rather, he’s
trying to maintain levels as a means to
avoid the withdrawal symptoms. Without
a cup he’d wake up in the middle of the
night with a headache.” Cornelis thinks
there’s a good chance her father’s genetic
profile has something to do with it.
While studies over the years have
shown that our social lives and demographics play a role in habitual caffeine
consumption, scientists have long suspected a genetic component. There have
been hints of it in studies of identical
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