Researchers evaluated the health data of 495,585 people who were tracked in an intensive study for an average of 10 years.
Of the group, 78 percent consumed either caffeinated ground coffee, instant coffee, or decaffeinated coffee, and 22 percent consumed no coffee. Throughout the study, there were 3,600 cases of chronic liver disease or steatosis, a buildup of fat in the liver. There were also 184 cases of hepatocellular carcinoma, a form of liver cancer.
The coffee drinkers in the study had a 21 percent reduced risk of developing chronic liver disease and a 20 percent lower risk of fatty liver disease. Study participants who drank coffee also had a 49 percent reduced risk of dying from chronic liver disease. The health benefits were most pronounced among those who drank caffeinated ground coffee. Although instant coffee and decaffeinated coffee were linked with health benefits, ground coffee had the largest effects.
According to the researchers, ground coffee contains the highest levels of kahweol and cafestol — two ingredients thought to protect against liver disease. The health benefits leveled off at four to five cups of coffee a day. The researchers say coffee could potentially be used as an affordable and accessible way to help decrease the risk of developing liver disease.
“Although also shown in previous studies, this paper appears to provide the most convincing to date that coffee consumption is associated with a decrease in liver-related mortality in a large population-based cohort,” said Dr. Joseph Lim, a Yale Medicine hepatologist and professor at Yale School of Medicine.
This study adds to the growing evidence that coffee benefits the liver, according to Dr. Albert Do, a Yale Medicine hepatologist, clinical director of the fatty liver disease program, and associate professor at Yale University.
“There are previous studies suggesting lower risk of cirrhosis (severe liver scarring), improvements in fatty liver disease, lower rates of hospitalization and mortality in cirrhosis, associated with coffee use,” Do said.
Many studies have shown that coffee consumption is linked to lower liver enzyme levels. Much of the time, high levels of liver enzymes aren’t a cause for concern, but they can be a sign of inflammation or damage in the liver. Another extensive review (Wiley.com) from 2016 found that drinking coffee may help offset liver damage associated from overconsuming certain foods and alcohol. According to Dr. Tamar Taddei, a Yale Medicine hepatologist and associate professor at Yale School of Medicine, it’s difficult to pinpoint how and why coffee may combat liver disease. “It may have anti-inflammatory or anti-fibrotic properties, the two main and interrelated pathways to liver disease and liver cancer,” Taddei said. There may also be other contributing factors at play that haven’t yet been identified.
More research is needed to explore how coffee — along with the ways in which its made — may improve the health outcomes in people with liver problems. “We need to learn much more about what components of coffee and what parts of the process of making coffee — from bean to cup — are beneficial,” Taddei said.
How Much Coffee Should You Drink?
The standard recommendation from Dr. Do is one to two cups of black, caffeinated coffee per day. People who develop heartburn or gastrointestinal issues should adjust their intake depending on what they can tolerate. In addition, people with severe cardiac disease or severe high blood pressure should avoid excess coffee if it aggravates their condition.
“Although individuals should continue to feel reassured that they can continue to drink coffee at current levels, I would not suggest increasing levels of consumption with the intent of improving liver outcomes,” Lim said.