Coffee drinkers of both caffeinated and decaffeinated types may have a lower risk of developing chronic liver disease compared to non-coffee drinkers, according to a large new study that adds to the research suggesting that coffee of all types may benefit liver health. The study was published in BMC Public Health.
Study adds to the evidence on coffee and liver cancer
AICR research shows strong evidence that drinking coffee lowers the risk of liver cancer. Chronic liver disease is a growing and major global health problem that can have serious effects and increase the risk of liver cancer. This latest study found a limited link with coffee reducing liver cancer risk, but it indicated an association. AICR’s report on liver cancer analyzing the worldwide evidence concluded that drinking just one cup of coffee per day lowers the risk of this cancer.
Daily coffee and lower liver disease
Previous observational and laboratory research show that coffee conveys benefits overall on liver disease but there is less known about what types or amounts are most protective. This new study aimed to better understand coffee and liver disease by investigating the association with the beverage overall along with the effects of instant, decaf, espresso and other coffee types.
The study included close to half a million individuals who were part of a long-term United Kingdom study called the UK Biobank. When people entered the study, they answered questions about their medical history, coffee consumption and other lifestyle habits. Most of the participants – 78 percent – reported drinking ground or instant caffeinated or decaffeinated coffee regularly; 22 percent did not drink coffee at all.
During a median follow-up of 10.7 years, approximately 9,000 developed chronic liver disease or steatosis, a build up of fat in the liver also known as fatty liver disease. There were 184 cases of hepatocellular carcinoma, the most common type of liver cancer.
Compared to non-coffee drinkers, coffee-drinkers of all types and amounts 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 lower risk of dying from chronic liver disease. This effect was seen after taking into account alcohol consumption, obesity, age, diabetes and other recognized risk factors.
Decreased risk was seen in one daily cup, with risk lowering slightly at greater amounts and benefits peaking at three to four cups per day.
Drinkers of decaffeinated, instant, and ground coffee – which includes espresso – each had lower risks of incident chronic liver disease and dying from the disease. Espresso and other forms of ground coffee showed the greatest benefits.
Lower risk for liver cancer and overall coffee consumption trended towards a decreased risk but the observed effect was not clear here. This was likely due to the small number of liver cancer cases and a shorter follow-up time compared to other studies, the authors note. Findings did show that any amount of ground coffee lowered risk of liver cancer.
Caffeinated, decaf and espresso
There are several proposed mechanisms that could explain why coffee may protect against liver cancer and other diseases. Coffee contains many phytochemicals, such as caffeine, chlorogenic acid, kahweol and cafestol. In lab and targeted human studies, these compounds are seen playing a role in reducing DNA damage and chronic inflammation, DNA repair, and lessening the effect of harmful compounds.
Coffee may also lower risk of type 2 diabetes by improving blood sugar levels and insulin sensitivity, which lowers the risk of liver cancer.
In this study, the greatest effect was seen with ground coffee, which contains relatively high levels of the compounds kahweol and cafestol. Yet given the protective effect of different types of coffee, each with its unique mixture of phytochemicals, there may be a complex relationship involving more than one active ingredient, the authors write.
Limitations and expanding the research
The BMC findings show an association between coffee and liver disease, not that drinking coffee is a cause of lower risk. And while this was a large study, which gives it strength, the study also has limitations similar to other observational human studies.
Participants only reported their coffee consumptions habits at one time, for example, which may have changed over the years of follow-up. The cup size amount may have varied and there was no information on ex-coffee drinkers, which may have an effect on later disease. Participants in this study were predominantly white and located in the UK, which makes the findings difficult to generalize to other populations.
Lowering the risk of liver disease and cancer: clear evidence
The numbers of people developing liver disease has increased around the world with incidence of liver cancer and cirrhosis on the rise. Liver disease includes alcohol-related liver disease (ALD), including cirrhosis, chronic hepatitis B and C infection, and non-alcoholic fatty liver disease (NAFLD). In NAFLD, the occurrence of fat build up in the liver is not caused by significant alcohol consumption. The serious form of this condition can cause inflammation and liver damage. It can also lead to liver cancer.
AICR’S report on liver cancer found that, along with drinking coffee, maintaining a healthy weight and drinking only moderate amounts of alcohol – or none – also lower risk.
Excess body fat increases the risk of non-alcoholic fatty liver disease. Having overweight and obesity is also a cause of many of the most common cancers, including colorectal, endometrial, and breast.
Alcohol is a clear cause of liver damage and may cause cirrhosis, which increases the risk of liver cancer; AICR research shows that having more than three alcohol drinks a day is a convincing cause of liver cancer.
Smoking is also a cause of liver cancer.
Early stages of liver cancer often do not produce symptoms, so the disease is often diagnosed at an advanced stage. You can read more about the risk factors for liver cancer and lifestyle steps to lower the risk on our Learn About Cancer section here.
The BMC Public Health study authors cite no specific funding received for the study.