Can't stop at just one cup of joe to wake up? You might be missing a certain variation of the PDSS2 gene, which instructs our bodies to break down caffeine more slowly. Researchers in Scotland report in the journal Scientific Reports that they interviewed and examined the DNA of nearly 3,000 coffee drinkers in Italy and Holland and found that those with the variation tended to drink roughly one less cup of coffee daily than others. A slower breakdown of caffeine means it stays in the body longer, so one cup is more likely to do the trick, explains LiveScience. Researchers, however, say further research is needed to fully understand what's going on.
The PDSS2 gene isn't the first to be implicated in caffeine consumption, reports Time. A major 2014 study of more than 120,000 coffee drinkers found six genetic markers associated with physical responses to caffeine. One researcher tells the magazine that coffee "is kind of controversial" because it is, to a degree, protective of some diseases for some people but may predispose others to diseases as well. "So understanding what is driving this and how we make food choices is very important." Some of the health benefits linked to coffee include a lower risk of type 2 diabetes, a longer life, and healthier arteries. (Apparently the claim that coffee causes heart palpitations is rubbish.)