Sometimes two vices are better than one. Drinking large amounts of coffee protects the livers of people who drink large amounts of alcohol, a new study shows. The results partly explain why so many heavy alcohol drinkers escape cirrhosis of the liver, say the authors.
The idea that coffee drinking might benefit alcohol users arose more than a decade ago, when cardiologist Arthur Klatsky and colleagues at the Kaiser Permanente Medical Care Program in Oakland, California, noticed that fewer heavy drinkers were dying of cirrhosis--scarring that hardens the liver--than expected. A study at the time suggested coffee drinking might be the cause, but it was too small to say to what extent. Other studies since then have suggested that coffee appears to lower the amount of liver damage as measured by liver enzymes in the blood in people who drink alcohol generously. But cirrhosis can also be caused by viruses such as hepatitis C, and the previous analyses could not say whether coffee also protected those people.
To find out, Klatsky and colleagues analyzed data from more than 125,000 individuals in the Kaiser health system who were deemed healthy in initial exams between 1978 to 1985. All of the individuals filled out questionnaires that asked how much coffee, tea, and alcohol they drank. By 2001, 199 had come down with cirrhosis of the liver due to drinking, and 131 had cirrhosis due to other causes. When the researchers compared those who had consumed similar amounts of alcohol, they found that for each cup of coffee consumed per day, individuals were 22% less likely to be hit with alcohol-induced cirrhosis. The heaviest coffee drinkers were 80% less likely to suffer cirrhosis. In addition, boozers who drank the most coffee had significantly lower amounts of liver enzymes in their blood, suggesting something in coffee protects from liver damage. Coffee had no effect on cirrhosis if the damage was not due to alcohol, and no amount of tea drinking helped anyone's liver, indicating that the effect was not due to caffeine. Klatsky says he was surprised at how well coffee worked. The team reports its results today in Archives of Internal Medicine.
"I think it's pretty exciting," says James Everhart of the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Maryland, who has also studied the connection between coffee and cirrhosis. Klatsky says the best way to avoid alcohol-induced cirrhosis is not to drink more than four cups of coffee a day but rather to cut back on the tipple. Still, "this is another indication that moderate coffee drinking is not harmful," he says.