Does drinking coffee protect against liver cancer?
Drinking coffee is consistently associated with a lower risk of liver cancer, and that association is better supported than for most other cancer types. Three or more cups per day appears to offer the most protection, but if you are pregnant, keep your intake low.
Liver cancer is the clearest example in which coffee drinking shows a protective effect. Large observational studies and so-called Mendelian randomisation studies both point in the same direction. That second method 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. Three or more cups per day appears to offer the most protection.
Why is this so striking? For most other cancer types the picture is far less clear. An umbrella analysis of many studies did find that heavy coffee drinkers had on average about 18% lower odds of cancer than people who drink little coffee, but this is an average across dozens of cancer types combined. For liver cancer specifically, the association is one of the most robustly supported in the coffee-and-cancer literature.
There are also points of caution. Coffee drinkers smoke more often, and in studies that do not correct for this adequately, coffee appears to be a risk factor for lung cancer. Whether any association with lung cancer truly remains after correcting for smoking is still unclear. There is also a signal that women who drink a lot of coffee have a slightly higher risk of bone fractures, although this evidence is limited and is not seen in men.
Are you pregnant? Different advice applies in that case. High coffee consumption is associated with a greater chance of low birth weight, preterm birth and miscarriage. Experts recommend limiting caffeine intake during pregnancy to a maximum of 200 mg per day, which amounts to roughly one to two cups.
Based on several large reviews and meta-analyses (PMID 39266809, 29167102, 40806142, 38963648), including studies that use Mendelian randomisation for the liver cancer association. The evidence for liver cancer is stronger than for most other cancer types.
Does green tea protect against cancer?
Drinking green tea is not a proven protection against cancer: cell and animal research is promising, but studies in humans contradict each other too often to draw a firm conclusion. A few cups a day is probably harmless; concentrated supplements are less certainly so.
Does eating a lot of sugar increase my risk of cancer?
Drinking large amounts of sugar-sweetened beverages is associated with a noticeably higher risk of certain cancers, particularly early-onset colorectal cancer and liver cancer. The association is observational, but consistent enough to make reducing soft drinks and fruit juice a concrete point of attention.
Does drinking less alcohol meaningfully reduce your cancer risk?
Drinking less alcohol meaningfully reduces your risk of several cancer types, although it takes years before the full effect becomes visible. Stopping sooner yields greater health gains.
Does alcohol increase your risk of cancer, even with one drink a day?
Yes, even one drink a day increases the risk of certain cancers, particularly breast and colorectal cancer. There is no safe lower threshold; drinking less or stopping reduces your risk immediately.
Does a chronic hepatitis B or C infection increase your risk of liver cancer?
Yes, a chronic hepatitis B or C infection strongly and demonstrably causally increases your risk of liver cancer. Get tested and treated if you carry the virus, and ask your doctor about periodic surveillance.
Does being overweight increase my risk of cancer, and if so, which types?
Excess weight increases your risk of at least 13 types of cancer, including uterine, colorectal, breast and liver cancer. Losing weight reduces that risk, although it remains unclear whether all methods of weight loss are equally effective for immune defence against cancer.