Scientists from the University of Toronto have found that the way coffee affects our kidneys isn’t the same for everyone. The difference depends on our genes — the small parts of our DNA that tell our bodies how to work.
One important gene, called CYP1A2, helps the body break down caffeine, which is the main active ingredient in coffee. Some people have a fast version of this gene, and others have a slow one. This difference affects how well the body handles caffeine and whether drinking coffee could be harmful to the kidneys.
To understand this better, think of genes like instruction books for the body. They tell our systems how to function. The CYP1A2 gene is like a speed controller for caffeine. If you have the fast version, your body acts like a race car — it quickly breaks down caffeine.
If you have the slow version, your body works more like a slow-moving snail — it takes much longer to process caffeine. Because of this, people with the slower gene may be more sensitive to caffeine and could have a higher risk of kidney stress if they drink too much coffee.
Kidneys are important organs that clean our blood. They help remove waste and extra fluid, keeping our bodies in balance. Taking care of them is very important, and that includes being aware of what we eat and drink — including coffee.
The research showed that for most people, drinking up to three cups of coffee a day is likely safe. In fact, up to four cups a day may be okay for many adults. But this general advice may not apply to everyone.
About half of all people in the world have the fast “race car” version of the gene, while the other half have the slow “snail” version. This means that for millions of people, too much coffee might put extra pressure on the kidneys.
There is now a simple test that can tell you which version of the gene you have. This test could help you decide how much coffee is right for you. For example, someone with the fast gene might be fine drinking a few cups a day. But someone with the slow gene may need to cut back to avoid kidney problems in the future.
This study reminds us that health advice should not be one-size-fits-all. Even something as common as drinking coffee can have different effects depending on who you are. By understanding our own bodies better, we can make smarter choices.
Besides watching your coffee intake, there are many ways to keep your kidneys healthy. Drinking enough water every day, eating a balanced diet with fruits and vegetables, and getting regular exercise all help. It’s also important to be careful with medications, especially painkillers, which can sometimes harm the kidneys if used too often or in high doses.
Scientists like Ahmed El-Sohemy, who led this study, continue to study how food, drink, and our genes work together to affect our health. Their research was published in the medical journal JAMA Network Open.
They hope that by learning more about how genes like CYP1A2 work, doctors and patients can better protect kidney health and make more personal health decisions — starting with something as simple as your daily cup of coffee.
If you care about kidney health, please read studies about drug that prevents kidney failure in 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 common painkillers may harm heart, kidneys and more.
Copyright © 2025 Knowridge Science Report. All rights reserved.
