A new study from the University of Toronto has uncovered an important link between how much coffee you drink and your risk of kidney disease—and it all comes down to your genes.
Published in the journal JAMA Network Open, the research highlights how a single gene can change the way your body handles caffeine and affect your kidney health.
Led by Professor Ahmed El-Sohemy, the study looked at a gene called CYP1A2. This gene controls how quickly your body breaks down caffeine. Some people have a version of the gene that lets them process caffeine quickly. Others have a different version that makes them process caffeine much more slowly.
The research showed that people who have the slow version of this gene and drink a lot of coffee—three or more cups a day—may be putting their kidneys at risk. These heavy coffee drinkers had nearly three times higher levels of kidney disease markers compared to others.
This helps explain why past studies have shown mixed results. Some research has said caffeine is bad for the kidneys, while other studies have suggested it might actually help protect them. But this new study shows that how your body handles caffeine may be the key.
The researchers looked at the amount of caffeine people were consuming—roughly 300 milligrams or more per day, which is about three cups of espresso—and compared it to signs of kidney problems. The risk seemed to appear mainly in those with the slow-metabolizing gene version.
About 50% of the people in the study—and the same percentage of the general population—have this slow caffeine-metabolizing gene. That means a lot of people could be at risk without even knowing it.
The study’s authors say that this is a good example of how personalized nutrition—diet advice based on your genes—can help people make better health decisions. Not everyone reacts the same way to foods and drinks, and our genes play a big role in those differences.
This research also raises awareness about the need to look more closely at how genetics can affect the way we respond to what we eat and drink. It opens the door for more studies on how other parts of our diet might interact with our genes, especially when it comes to long-term health.
In the future, personalized healthcare based on genetic testing could help people know whether their caffeine habits are safe or need to change. It’s another step toward more tailored advice that fits each person’s unique biology.
In conclusion, the University of Toronto study offers valuable insight into how a common habit like drinking coffee can have very different effects depending on your genetic makeup. If you’re someone who drinks multiple cups of coffee a day, it might be worth learning more about your genes—and thinking about how they might affect your health.
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