Coffee is enjoyed all over the world, perhaps more than any other substance except for water and air. We all are familiar with the stimulant effects of coffee, and independent of this effect caffeine is also a weak mood-elevating substance. There are many social rituals that revolve around coffee too. In fact, this blog probably would not exist if it wasn’t for strong black coffee (I would be sleeping instead of writing!)
However, did you know that coffee is good for your liver? There are numerous studies that show some correlation between a healthy liver coffee intake. Researchers are not entirely sure if it is coffee as a whole (which is composed of many different substances) or caffeine itself (the stimulant substance in coffee) that has the beneficial effect. What does seem to be clear, is that people at risk for chronic liver disease who drink coffee (studies have shown as little as one cup per day) seem to develop less fatty liver disease, less cirrhosis, less liver cancer, and are less likely to die as a result of chronic liver disease!
The hepatic stellate cell is the mediator of liver fibrosis (scarring) and eventually cirrhosis. When activated by various insults to the liver (e.g., alcohol, chronic hepatitis, etc.), the stellate cell starts laying down proteins that promote scar tissue formation. One theory on how coffee improves liver disease is that caffeine inactivates these stellate cells, thereby slowing the process of cirrhosis.
We must be cautious to not put too much weight in these studies however. Mostly, they are retrospective cohort studies, and therefore rely on self-reporting of coffee intake. The self-reporting bias is well known and can skew the results dramatically. Also, retrospective studies can only demonstrate correlation, not causation. It’s one thing to say “coffee drinkers often have less liver disease.” It’s another thing entirely to say, “drinking coffee prevents liver damage.”
As a gastroenterologist, I often tell people to limit coffee intake for various reasons. For example, coffee can contribute to acid reflux. In some people, coffee can overstimulate the GI tract and cause diarrhea. Too much caffeine can cause anxiety, poor sleep, or heart arrhythmias. Drinking a $5+ coffee drink from Starbucks with cream and sugar may also negate any health benefit of coffee since the extra calories and fat probably do more damage in the long run, not to mention the detrimental effect on your bank account. However, if we are just focusing on the liver, I can tell you to drink that coffee up!
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Khalaf N, White D, Kanwal F, et al. Coffee and caffeine are associated with decreased risk of advanced hepatic fibrosis among patients with hepatitis C. Clin Gastroenterol Hepatol 2015;14:S1542-3565.
Morisco F, Lembo V, Mazzone G, et al. Coffee and liver health. J Clin Gastroenterol 2014;48:S87-90.
Setiawan VW, Wilkens LR, Lu SC, et al. Association of coffee intake with reduced incidence of liver cancer and death from chronic liver disease in the US multiethnic cohort. Gastroenterology 2015;148:118-25.
Wang Q, Dai X, Yang W, et al. Caffeine protects against alcohol-induced liver fibrosis by dampening the cAMP/PKA/CREB pathway in rat hepatic stellate cells. Int Immunopharmacol 2015;25:340-52.
Image via Julius Schorzman