A daily coffee habit may do more than perk you up in the morning.
“What surprised me most was how consistent the signal was,” says the lead study author, Hyunseok Kim, MD, PhD, MPH, a transplant hepatologist and an assistant professor of medicine at Cedars-Sinai Medical Center in Los Angeles.
“The practical message is that, for people who already enjoy coffee and tolerate it well, moderate coffee intake can be part of a liver-healthy lifestyle,” Dr. Kim says.
Study Followed More Than 350,000 Participants for Over 13 Years
Researchers collected data from 354,957 UK Biobank participants, who joined the study between 2006 and 2010. All were 40 to 69 years old when they started, and none had cirrhosis (liver scar tissue) or liver cancer at that time.
Participants reported how much coffee they drank, whether they usually drank regular or decaf, and whether they sweetened their drinks.
Researchers followed participants for about 13 years, tracking new cases of cirrhosis, liver cancer, and liver-related death through their linked health records.
This study went further than previous research into coffee and liver health by incorporating liver MRI scans for nearly 30,000 participants and blood protein analyses in another 44,000.
“This allowed us to look not only at whether coffee was associated with better outcomes, but also at potential biological pathways behind that association,” Kim explains.
Coffee Drinkers Showed Significant Liver Benefits
The study found that, compared with people who did not drink coffee, those who drank 5 or more cups a day had:
- A 32 percent lower risk of cirrhosis
- A 47 percent lower risk of liver cancer
- A 42 percent lower risk of liver-related death
The liver health benefit appeared to be dose-related — as coffee intake increased, liver disease risk seemed to decrease.
But the researchers note that people who drank 1-2 and 3-4 cups per day also experienced reductions in liver disease risks.
Scanning revealed specific liver benefits: People who drank more coffee had lower levels of liver fat and liver iron, as well as lower odds of elevated cT1, an MRI marker linked to liver inflammation.
How Might Coffee Lower Liver Disease Risk?
Kim points out that both regular and decaf coffee drinkers experienced protective benefits, suggesting that caffeine may not be the “whole explanation.”
Pichamol Jirapinyo, MD, MPH, an assistant professor of medicine at Harvard Medical School in Boston and a bariatric and advanced endoscopist at Mass General Brigham, who was not involved in the research, points instead toward the antioxidants and polyphenols found in coffee.
These beneficial compounds may reduce oxidative stress and chronic inflammation, both of which contribute to liver injury, says Dr. Jirapinyo, who serves as a spokesperson for the American Gastroenterological Association.
Experimental studies suggest these compounds may also decrease fat accumulation in the liver, reduce the activation of scar-forming cells, and limit the development of fibrosis, she adds.
The Study Has Strengths and Limitations
“Overall, I think this is one of the strongest observational studies we’ve seen on coffee and liver health,” says Jirapinyo. “What makes it stand out is not just its size, but also the integration of clinical outcomes,” like MRI results and blood work, she says.
Still, the study has some limitations, Kim says. For one thing, it is an observational study, a type of research that can prove that two things are linked (in this case, coffee drinking and decreased liver disease), but not that one causes the other.
“Coffee intake was self-reported, and people who drink coffee may differ from nondrinkers in other ways despite careful adjustment,” Kim says.
And while the researchers adjusted data for factors that could influence liver health (including age, sex, smoking, alcohol use, body mass index, diabetes, high blood pressure, and genetic variants linked to liver disease risk), they note the UK Biobank population is largely white, which may limit how broadly the findings apply.
Should You Drink More Coffee for Liver Health?
Despite the promising findings, Kim says you should not start drinking coffee solely for liver health. Instead, the study should reassure coffee drinkers that moderate coffee consumption may fit into a liver-healthy lifestyle.
“Coffee should complement, not replace, the fundamentals — avoiding excessive alcohol, maintaining a healthy weight, exercising, and managing diabetes, cholesterol, and blood pressure,” he says.
For most adults who already tolerate coffee well, 1 to 4 cups a day appears to be a sensible range, based on this study and the broader evidence, Jirapinyo says.
“More isn’t necessarily better,” she says. “This study observed an association, not proof of causation, and it wasn’t designed to determine the ‘optimal’ dose of coffee.”
Drinking too much coffee can cause side effects like insomnia, anxiety, heart palpitations, or stomach pain, Jirapinyo says. For people sensitive to caffeine, decaf may be a safer option.
“If you already enjoy coffee, there’s no reason to feel guilty about your morning cup or two,” she says. “But I wouldn’t encourage someone who dislikes coffee or cannot tolerate caffeine to start drinking it solely for liver disease prevention.”
People who are pregnant, have severe reflux, heart arrhythmias, anxiety, insomnia, or caffeine sensitivity should be cautious about regular coffee intake, Kim says.
And while the findings also applied to people who added sugar or artificial sweeteners to their coffee, additives were linked to “modestly higher” MRI markers for liver inflammation.
“I would generally favor unsweetened coffee or minimizing sugar, especially for people with obesity, diabetes, or metabolic risk factors,” Kim says.
Source link