When you grab a cup of coffee, there's a good chance that you're more concerned about how fast it will wake you up than what else it might be doing to your body.
The study, which was recently published in JAMA Network Open, involved 1,180 adults who were between 18 and 45 years old and had untreated stage 1 hypertension (high blood pressure).
While the study lasted roughly 16 years, the participants were each checked out during a follow-up that occurred within a span of seven and a half years.
While taking a look at the results, they first noted that the rs762551 variant of the CYP1A2 gene was present in around half of the participants, which means that their body doesn't metabolize caffeine as quickly as they might otherwise.
They also found that those who metabolized caffeine slower were 2.7 times more likely to end up dealing with kidney dysfunction if they drank three cups of coffee or more each day.
At the same time, Betz points out, "It is important to remember that this study found a higher risk of kidney dysfunction in people who drank more than 3 cups of coffee per day. That is quite a bit!"
Most other studies have found a reduced risk of kidney disease in people who drink coffee. It is important to interpret all findings together.
Beyond that, she points out that "the study did not adjust for other dietary factors we know impact kidney health."