Researchers from the University at Buffalo have found that beginning at puberty, caffeine affects males and females differently — even with low doses, heart rates decreased more for boys than for girls and their systolic blood pressure went up higher.
Researchers do not know what's behind the different reactions, Time reports, and if it has anything to do with hormones. The study participants were given just one and two milligrams of caffeine, which is a drop in the bucket compared to the levels in caffeinated energy drinks that are popular with kids.
The FDA stated in 2013 that it would look into added caffeine in drinks marketed for young people. Right now, caffeine is not regulated — the FDA treats it like an ingredient, not a drug, since it occurs naturally in coffee beans and tea leaves — and companies are not required to include the amount of caffeine on food and drink labels. Energy drinks are sold as dietary supplements, getting them out of most FDA labeling requirements.
The results of the study were published in the journal Pediatrics.