Researchers from the University of Toronto and other institutions have discovered that heavy coffee drinking can increase the risk of kidney problems for some people, depending on their genes.
Specifically, the study found that people who drink three or more cups of coffee a day, which is roughly 300 milligrams of caffeine, may be at higher risk for kidney dysfunction if they have a specific version of a gene called CYP1A2. This gene is responsible for how the body processes caffeine.
People with the slow-metabolizing variant of the CYP1A2 gene have a harder time breaking down caffeine in their bodies. Because of this, caffeine lingers in their system longer and can build up to harmful levels.
This buildup can lead to kidney problems over time. On the other hand, people with a different version of the CYP1A2 gene are fast metabolizers. They can break down and clear caffeine from their bodies more efficiently, so even if they drink a lot of coffee, it does not seem to harm their kidneys in the same way.
Interestingly, about 50% of the population carries the slow-metabolizing version of the CYP1A2 gene. This means that half of all people might be at risk of kidney issues if they drink too much coffee regularly.
The researchers looked for three specific signs of kidney dysfunction in their study: albuminuria (which is when too much protein is found in urine), hyperfiltration (which is when the kidneys filter blood too quickly, potentially causing damage), and high blood pressure. All three are warning signs of kidney problems.
Their findings showed that people with the slow-metabolizing gene variant who drank large amounts of coffee had almost three times the markers of kidney disease compared to those who did not drink as much coffee or had the fast-metabolizing gene variant. This suggests that the inability to process caffeine efficiently can put extra stress on the kidneys, leading to long-term damage.
The researchers believe that this study highlights the importance of personalized nutrition. People may need to adjust their coffee intake based on their genetic makeup.
In fact, many genetic testing companies now include CYP1A2 in their reports to help people understand how their bodies process caffeine and other substances. Personalized nutrition could be a key to preventing health problems like kidney disease for those who are more sensitive to caffeine.
Current guidelines in Canada and the United States recommend that healthy adults consume no more than 400 milligrams of caffeine per day, which is roughly four cups of coffee. But this study suggests that for people with the slow-metabolizing version of the CYP1A2 gene, even 300 milligrams could be too much.
To protect kidney health, there are some important steps people can take. Maintaining a healthy lifestyle is crucial—eating a balanced diet, staying active, and keeping a healthy weight can all help lower the risk of kidney problems.
Managing health conditions like diabetes and high blood pressure is also important, as these are major risk factors for kidney disease. Drinking plenty of water helps flush out toxins and prevent kidney stones, while avoiding smoking and excessive alcohol consumption can protect the kidneys from damage.
People should also be careful with over-the-counter medications, especially pain relievers, which can be harsh on the kidneys if taken too often. Following the recommended doses and talking to a doctor if there are concerns can help prevent unnecessary kidney strain.
Regular check-ups are also important, especially for those with a family history of kidney disease. Blood pressure and kidney function tests can catch problems early, making them easier to manage.
The study, led by Ahmed El-Sohemy, was published in JAMA Network Open. It provides strong evidence that heavy coffee drinking is not equally safe for everyone. For people with the slow-metabolizing version of the CYP1A2 gene, cutting back on coffee could help protect their kidneys from long-term damage.
This research also highlights the growing importance of personalized nutrition, where a person’s diet is tailored to their unique genetic profile to prevent health problems before they start. For people who love coffee but want to protect their health, understanding their own body’s ability to process caffeine could make all the difference.
If you care about kidney health, please read studies about how to protect your kidneys from diabetes, and drinking coffee could help reduce risk of kidney injury.
For more information about kidney health, please see recent studies about foods that may prevent recurrence of kidney stones, and eating nuts linked to lower risk of chronic kidney disease and death.
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