For most of us, this is welcome news: According to the National Coffee Association, 62 percent of Americans drink coffee every day, and the average coffee drinker consumes slightly more than three cups per day. Chronic liver disease affects 4.5 million American adults, according to the Centers for Disease Control and Prevention. RELATED: 9 Questions You Should Be Able to Answer About Your Liver The reduced risk was observed across different coffee types, such as instant, ground, and decaffeinated, says Oliver Kennedy, PhD, a professor at the University of Southampton in England and the lead author of the study. These benefits may mean coffee could be an easily accessible preventive treatment for chronic liver disease, he says. People were followed over a median of 10.7 years and monitored for the development of chronic liver disease and related liver conditions. Out of the group, 78 percent (384,818) of the participants were coffee drinkers and drank an average of two cups of coffee a day; 22 percent (109,767) did not drink any type of coffee. Of the coffee drinkers, 55 percent drank instant coffee, 23 percent drank ground coffee (espresso included), and 19 percent drank decaf. During the study period, there were 3,600 cases of chronic liver disease, including 301 deaths. There were 5,439 cases of chronic liver disease or steatosis, also known as fatty liver disease, which is a buildup of fat in the liver, and 184 cases of hepatocellular carcinoma, a type of liver cancer. To isolate the impact of coffee on liver disease, researchers controlled for several factors, including smoking status, diabetes, body mass index (BMI), ethnicity, alcohol consumption, and the Townsend deprivation score, which is a way to determine socioeconomic status. The UK Biobank assigned a Townsend deprivation score to each participant according to their zip code and average levels of employment, home and car ownership, and household overcrowding. Compared with non-coffee-drinkers, coffee drinkers had a 21 percent reduced risk of chronic liver disease, a 20 percent reduced risk of chronic or fatty liver disease, and a 49 percent reduced risk of death from chronic liver disease. Any type of coffee was associated with a reduced risk of developing and dying from chronic liver disease compared with not drinking coffee, with the greatest benefit seen by people who drank ground coffee and consumed three to four cups per day.
Findings Confirm Earlier Studies on the Benefits of Coffee for Liver Health
“This research adds strength to what previous studies have found regarding the benefits of coffee for liver health,” says Omar Massoud, MD, PhD, the chief of the hepatology section at Cleveland Clinic in Ohio. Dr. Massoud was not involved in the new research. An earlier study, published in Gastroenterology, found that, compared with non-coffee-drinkers, people who drank two to three cups of coffee per day had a 38 percent reduced risk of liver cancer death and a 46 percent reduced risk of chronic liver disease death; those figures rose to 41 percent and 71 percent, respectively, in people who drank four or more cups a day. Another earlier study that looked at coffee consumption and liver disease, published in the Archives of Internal Medicine, also found a reduced risk of liver disease in coffee drinkers, and researchers concluded that coffee had a protective effect against cirrhosis, especially alcoholic cirrhosis. In that study, investigators found that coffee drinking was related to a lower prevalence of high aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. These enzymes are released into the bloodstream when the liver is damaged and are associated with liver damage and disease, according to MedlinePlus. The latest study, while strong, does have several limitations that need to be considered, Massoud says. The investigators asked about coffee consumption only at the start of the study, and so participants’ coffee drinking habits may have changed over the course of the study and follow-up. Additionally, he says, “Although the investigators controlled for several factors including BMI, there could be factors that influenced the findings that they didn’t account for.” The authors acknowledge that the results were not adjusted for waist circumference, which may be related to metabolic syndrome independently of BMI.
What Could Be Behind the Protective Effect of Coffee on the Liver?
“There are a variety of different chemical compounds in coffee that may be responsible for the protective effect,” says Dr. Kennedy. Two such compounds, cafestol and kahweol, are collectively known as diterpenes. These fat-soluble compounds appear in relatively high concentrations in French press coffee and espresso. Chlorogenic acid (CGA), a kind of polyphenol or plant-based compound found in coffee, is thought to have antioxidant properties. These acids may help regulate glucose in the liver and small intestine, according to ScienceDirect. RELATED: All About Caffeine Sensitivity
Further Research Is Needed to Confirm Findings on Coffee and Liver Health
It’s important to note that the study didn’t show that coffee caused the reduced risk of liver disease, says Kennedy. “There may be other attributes of coffee drinkers that explain the protective effect against liver disease, although we did adjust for the main known risk factors. Ideally, we would need a randomized controlled trial in order to make specific recommendations,” he says. Massoud says that the gold standard would be a study in which some people would be randomly assigned to drink coffee or not drink coffee and they would be observed and evaluated over an extensive period of time. “Ideally, this would also be ‘double-blinded,’ which would mean that neither the participants nor the researchers would know who was drinking coffee and who was not, which would be difficult to achieve,” he says. It might be more feasible to test a capsule that contained the compounds found in coffee against a placebo, says Massoud.
Should People Up Their Coffee Consumption for Liver Health?
“Even though cause and effect are not established in this study, there have been other studies that have confirmed the same point,” says Massoud. Coffee appears to have a protective effect against liver disease, and people who drink coffee regularly tend to have less liver disease. Considering that coffee is safe, is something many people normally drink, and has other benefits, it’s probably a good practice from a health perspective to drink more, unless you already consume three or four cups a day, says Massoud. Just be aware that coffee isn’t medicine, and if you are sensitive to caffeine (even decaf can have trace amounts), you may want to skip the java or at least consult your doctor about making any changes to your diet, especially if you have a history of liver problems.
