Does drinking coffee protect against liver cancer?

Yes, drinking coffee is consistently associated with a lower risk of liver cancer. That association is more robustly supported than for almost any other type of cancer. Both large population studies and genetic research point in the same direction. That genetic research is more rigorous than an ordinary questionnaire study, because it does a better job of ruling out other lifestyle factors as the cause of the association. People who drink three or more cups of coffee a day develop liver cancer less often, but that it is caused by the coffee has not been proven through intervention studies.

What about other cancers? An umbrella analysis found that people who drink a lot of coffee develop cancer on average about 18% less often than people who drink little to no coffee, but this is an average across dozens of cancer types combined. For most cancer types the picture is unclear. For liver cancer the association is the strongest and most consistent. Whether you drink regular coffee, caffeinated or decaffeinated, the brand or origin does not matter. Discuss this with your doctor if you have questions about your personal risk.

There are also points of attention. Coffee drinkers smoke more often, and in studies that do not correct for this adequately, coffee sometimes appears to be a risk factor for lung cancer. Whether a real association remains after correcting for smoking is still unclear. There is also a signal that women who drink a lot of coffee have slightly more bone fractures, although this has not been confirmed in genetic research.

Are you pregnant? Different advice applies in that case. Research found that pregnant women who drank more coffee gave birth prematurely more often, or more often had a child with a low birth weight. Limit caffeine intake during pregnancy to a maximum of 200 mg per day, which is approximately two cups. Discuss this with your doctor.