Coffee is one of the most popular drinks in the world. Many people start their day with a cup of coffee and continue drinking it throughout the day to stay alert and focused.
Coffee is often linked to benefits such as improved concentration and lower risks of certain diseases. However, scientists have long debated whether drinking a lot of coffee is good or bad for long-term health. A new study suggests that the answer may depend on your genes, especially when it comes to kidney health.
Researchers from the University of Toronto and other institutions recently carried out a detailed study to understand how heavy coffee drinking affects the kidneys.
They were especially interested in why coffee seems harmless for some people but problematic for others. To explore this, they looked at a specific gene called CYP1A2. This gene plays an important role in how fast the body breaks down caffeine.
People can be divided into two broad groups based on this gene. Some people are fast caffeine metabolizers, meaning their bodies process and remove caffeine quickly. Others are slow metabolizers, meaning caffeine stays in their system for a much longer time. These differences are invisible in daily life, but they can strongly influence how caffeine affects the body.
To explain this idea, imagine two people who both drink several cups of coffee every day. Even though they drink the same amount, their bodies react differently. A slow metabolizer keeps caffeine circulating in the blood for hours longer than a fast metabolizer. Over time, this longer exposure may place extra stress on certain organs, including the kidneys.
The researchers analyzed health data from participants who consumed large amounts of coffee, usually more than three cups a day or around 300 milligrams of caffeine.
This level is close to the daily caffeine limit that health authorities in countries like Canada and the United States consider safe for most adults. Despite being within these limits, the study found important differences in kidney health based on genetic makeup.
Among people who were slow caffeine metabolizers and heavy coffee drinkers, the researchers found nearly three times more signs of kidney stress compared to fast metabolizers.
They measured several indicators of kidney health, including excess protein in urine, how hard the kidneys were working to filter blood, and blood pressure levels. All of these markers are commonly used by doctors to assess kidney function and detect early damage.
One of the key findings was a higher rate of albuminuria, which means too much protein leaking into the urine. This can be an early warning sign of kidney disease. The study also found hyperfiltration, a condition where the kidneys work harder than normal, which can cause long-term damage.
High blood pressure was also more common in this group, adding another risk factor for kidney problems.
Past research on coffee and kidney health has produced mixed results. Some studies suggested that caffeine could harm the kidneys, while others suggested coffee might protect them.
This new research helps explain why results have been so inconsistent. It shows that genetics can change how coffee affects the body, meaning the same habit can be safe for one person but risky for another.
About half of the population carries the slow-metabolizing version of the CYP1A2 gene. This means a large number of people may be more sensitive to high caffeine intake without realizing it. As a result, interest in genetic testing has grown.
Some clinics and companies now offer tests that identify how quickly a person metabolizes caffeine and provide personalized dietary advice.
The study was led by researcher Ahmed El-Sohemy and published in JAMA Network Open. The researchers emphasize that they are not suggesting everyone should stop drinking coffee. Instead, they highlight the importance of understanding personal differences.
For people who drink a lot of coffee and may be slow metabolizers, reducing intake could help protect kidney health.
This research supports the growing idea of personalized nutrition, which focuses on tailoring diet advice to individual genetics and health profiles. It recognizes that there is no single diet that works equally well for everyone.
As science continues to uncover how genes influence our response to food and drink, personalized health strategies may become an important part of disease prevention.
For coffee lovers, this study offers a reminder that knowing your body matters. Understanding how your genes interact with caffeine could help you enjoy coffee safely while protecting your long-term health.
If you care about kidney health, please read studies about pesticide linked to chronic kidney disease, and this drug may prevent kidney failure in people with diabetes.
For more health information, please see recent studies about drug duo that may treat kidney failure, and results showing these vegetables may protect against kidney damage.
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