A large new study suggests that people who regularly drink coffee may have a lower risk of several serious liver problems.
Researchers found links between higher coffee intake and lower rates of liver scarring, liver cancer and death from liver disease.
The research was conducted by investigators at Cedars-Sinai Health Sciences University and was published in Clinical Gastroenterology and Hepatology. The team studied more than 355,000 adults and followed their health for more than a decade, making this one of the largest studies to examine coffee and liver health in detail.
The liver performs hundreds of jobs that keep the body working. It helps process nutrients, removes harmful substances from the blood, stores energy and produces important proteins, but years of damage can gradually reduce its ability to perform these tasks.
One serious form of liver damage is cirrhosis, in which healthy liver tissue is replaced by scar tissue. Cirrhosis can develop after years of heavy alcohol use, fatty liver disease, viral hepatitis or other conditions and can eventually lead to liver failure or liver cancer.
Previous studies have often found that coffee drinkers have better liver outcomes. However, many of those studies were smaller or focused only on diagnoses, while the new research combined long-term health records with detailed liver scans and measurements of proteins in the blood.
The researchers analyzed 354,957 people taking part in the UK Biobank who did not have cirrhosis or liver cancer when the study began. They then followed participants for a median of 13 years and recorded new cases of cirrhosis, liver cancer and deaths caused by liver disease.
A clear pattern appeared when coffee drinkers were compared with people who did not drink coffee. Those consuming five or more cups a day had a 32% lower risk of cirrhosis, a 47% lower risk of liver cancer and a 42% lower risk of dying from liver disease.
That does not mean people need to drink five cups every day to potentially benefit. The researchers saw favorable associations even among people drinking one or two cups, while the strongest overall pattern appeared at around three to four cups a day.
Importantly, the researchers are not recommending that people increase their intake to five or more cups. Large amounts of caffeine can cause sleep problems, nervousness, a racing heartbeat and other unwanted effects, and some people need to limit caffeine for medical reasons.
The study also provided clues about what might be happening inside the liver. MRI scans showed that people who drank more coffee tended to have less fat and iron stored in the liver, as well as fewer signs of inflammation and fibrosis, which is the buildup of scar tissue.
Blood analyses told a similar story. Coffee drinkers had higher levels of some proteins associated with healthy liver function and lower levels of proteins linked with inflammation and scarring.
Another interesting finding was that both caffeinated and decaffeinated coffee were linked with better liver outcomes. This suggests that caffeine alone probably does not explain the association.
Coffee contains many naturally occurring substances, including plant compounds that can affect inflammation and other processes in the body. Researchers now want to identify which compounds may be responsible and understand how they might influence pathways involved in liver damage and repair.
The results are particularly relevant because liver disease is a growing health problem. Metabolic dysfunction-associated steatotic liver disease, formerly widely known as fatty liver disease, has become increasingly common alongside obesity and type 2 diabetes.
Still, the study cannot prove that coffee prevents liver disease. It was observational, meaning researchers recorded people’s existing coffee habits rather than randomly assigning them to drink different amounts, so coffee drinkers may differ from non-drinkers in other ways that affect health.
There may also be differences in the type of coffee people drink, how it is prepared and what is added to it. A plain cup of coffee is very different nutritionally from a large drink containing substantial amounts of sugar, cream or flavored syrup.
The study therefore should not be viewed as a reason to use coffee as a treatment. Proven ways to protect the liver still include maintaining a healthy weight, exercising, limiting alcohol, avoiding unnecessary liver-damaging substances and managing blood sugar, cholesterol and blood pressure.
People who already enjoy coffee and tolerate it well can take some reassurance from the findings. But those with insomnia, severe anxiety, uncontrolled high blood pressure, certain abnormal heart rhythms or other conditions affected by caffeine should discuss their intake with a health professional.
Overall, the study is unusually strong because of its very large sample, long follow-up period and use of scans and blood measurements in addition to medical records. These extra biological findings make the association more convincing than a simple survey showing that coffee drinkers happened to develop less liver disease.
However, the central limitation remains important: association is not proof of cause and effect. Future research needs to identify the substances in coffee that may protect the liver and determine whether they directly reduce inflammation and scarring before coffee can be considered a true preventive tool.
If you care about liver health, please read studies about a diet that can treat fatty liver disease and obesity, and coffee drinkers may halve their risk of liver cancer.
For more health information, please see recent studies that anti-inflammatory diet could help prevent fatty liver disease, and results showing vitamin D could help prevent non-alcoholic fatty liver disease.
Source: Cedars-Sinai Health Sciences University.
