Protect your liver with coffee

The myth persists that coffee is bad for you. It's probably because people assume that anything they enjoy must be bad for them. The truth is that coffee is good for you, although the jury is still out as to exactly why. (The prevailing theory is that its positive effects are at least partially due to its high antioxidant content, but rest assured, the research continues.)

One of the many paths of research into coffee consumption has been related to the liver: there's been research suggesting that drinking coffee reduces the risk of liver cancer, cirrhosis, and chronic liver disease. With that in mind, researchers affiliated with Johns Hopkins University made use of data gathered through the ARIC (Atherosclerosis Risk in Communities) study to see if coffee consumption was linked with liver-related hospitalizations (Eur J Clin Nutr 2019(73):1133-1140).

The ARIC study began recruitment in 1987 in four United States communities: Jackson, Mississippi; Minneapolis, Minnesota; Forsyth County, North Carolina; and Washington County, Maryland. Over 15,000 men and women between the ages of 45 and 64 were initially recruited, and the study is ongoing.

At the initial recruitment and at regular intervals thereafter, the participants had their height and weight measured, filled out detailed dietary questionnaires, and gave blood for metabolic testing.

At the first visit, between 1987 and 1989, and at the third visit, between 1993 and 1995, the participants met with a trained interviewer who asked them about their dietary intake in more detail, including how often they consumed 8-ounce cups of caffeinated coffee.

The researchers affiliated with the ARIC study monitor the hospitals in each participant group's area in case a study participant is admitted to the hospital. Further, the researchers also contact the participants every year by phone to assess their health, asking if they had been hospitalized in the past year. If a study participant was admitted to the hospital, the authors contacted the hospital to ascertain the reason for admission, in this case focusing specifically on liver-related admissions.

The coffee intake of those who were hospitalized with liver-related diagnoses was compared with those who were not hospitalized with a liver-related diagnosis. After taking into account such variables as age, race, smoking status, level of physical activity, DASH diet score, and alcohol intake, the authors found that those who drank 3 or more cups of coffee per day were 20% less likely to be hospitalized for a liver-related diagnosis than those who did not drink coffee at all.

Those who drank between 1 and 3 cups of coffee per day were about 17% less likely to be hospitalized, while those who drank less than 1 cup of coffee per day were 14% less likely to be hospitalized for a liver-related problem.

What's interesting about this analysis is that those who drank the most coffee tended to be white males who also smoked and drank - people one would expect to have more trouble with their liver, not less.

What this means for you

This study can only show that drinking more coffee is related to lower hospital admissions for liver-related problems, not that drinking coffee prevents those admissions. It does, however, add to our growing body of information suggesting that regular coffee is not bad for you.

First posted: December 11, 2019