Study: Your Coffee Addiction Could Be Causing Damage to Your Kidneys

Do you drink three or more cups of coffee a day? You might want to consider scaling back: All that caffeine could be damaging your kidneys, according to a new study.

A recent JAMA report from researchers from the universities of Toronto, Canada, and Padova, Italy, explored the link between high coffee consumption and kidney function. As MedicalNewsToday reported, research on this topic has historically generated conflicting results. (Coffee does have some documented health benefits, after all.) However, this new study may offer an explanation for the confusion.

Researchers found that drinking three or more cups of coffee per day can be linked to kidney dysfunction over time — but this is not the case for everyone. Apparently, it all depends on how quickly your body metabolizes caffeine.

In the study, roughly half of the 1,180 participants had a variant of the CYP1A2 gene called rs762551, which causes them to metabolize caffeine more slowly. Among this group, people who reported high coffee intake were 2.7 times more likely to develop kidney dysfunction. They were also at an increased risk for hypertension, or high blood pressure.

Interestingly enough, this was not the case for participants who didn’t have the problematic variant. This key factor could explain why previous studies of caffeine’s effect on our kidneys have been so inconclusive.

“It was remarkable to see just how striking the effects of coffee were in the group that had this genetic variant, yet no effect whatsoever in those who did not,” Dr. Sara Mahdavi, a researcher with the University of Toronto and the study’s lead author, told MedicalNewsToday.

It’s worth noting that the JAMA study specifically investigated the effects of caffeine, the chemical in coffee that makes you feel energized (or anxious and jittery, if you’ve had too much). “[D]ecaffeinated coffee is virtually devoid of caffeine, [so] those who consume decaf would not have a higher risk of kidney dysfunction, regardless of their genetics,” Mahdavi added.

Researchers hope their findings will prompt the U.S. Food and Drug Administration (FDA) to reevaluate its recommendations for caffeine consumption, which now stand at four to five cups of joe per day for healthy adults.

If you’re anything like me, then your daily coffee consumption is… impressive. I regularly chug three to four cups per day, although working from home during COVID has helped me cut down on java. All this to say, since Idon’t know if I have the rs762551 variant, perhaps it’s best to cap it off at two cold brews. Everything in moderation, you know?

Before you go, check out these quotes to inspire healthy attitudes around food: