Attention, coffee drinkers.
If you think your craving for a cuppa joe stems from sleepiness, habit or simply a desire to make Starbucks CEO Howard Schultz an even richer man, you are sorely mistaken.
A team of researchers from Harvard, the National Cancer Institute and other esteemed institutions of biological science reports that our need for caffeine is in our DNA.
There are two of these so-called caffeine genes, according to a report published this spring in PLoS Genetics.The first is CYP1A2, which had already been known to have something to do with caffeine metabolism, and the second is AHR, which plays a role in regulating CYP1A2.
Everyone has both of these genes, of course, but we don't all have the exact same kinds. Those in the study who had the most caffeine-seeking version of CYP1A2 drank an average of 38 milligrams more of the stuff each day than those with the most caffeine-indifferent version.
People with the most caffeine-dependent version of the AHR gene consumed an average of 44 milligrams more per day than their counterparts with the least caffeine-seeking version.
That works out to about the same amount of caffeine as is found in a single can of Coke or Pepsi or in a cup of tea.
The researchers made this discovery by comparing the genes and caffeine consumption habits of more than 47,000 Americans of European descent.
The search was important because caffeine "is the most widely consumed psychoactive substance in the world," with nearly nine out of 10 adults eating or drinking it regularly, they explained in their report.
More than 80 percent of the caffeine consumed by study participants was delivered in the form of coffee.