Coffee as a preventative measure against liver cancer
Dr Veronica Wendy Setiawan - University of Southern California, Los Angeles, USA
Can you tell us more about the relationship between coffee intake and cancer?
We’ve found that increasing coffee consumption is associated with reduced risk of hepatocellular carcinoma.
How was the study carried out?
We looked at data from a big prospective cohort study that’s called the multi-ethnic cohort where we have close to 180,000 people for this particular analysis that were followed close to 18 years for liver cancer incidence. We also asked questions about participants’ coffee consumption at baseline.
What did you find?
What we found is that with increasing number of coffee consumption there’s a significant reduction in hepatocellular carcinoma in the five different ethnic groups that we have. There’s significant dose response.
Wasn’t this data already in the literature?
Most data came from populations outside the US. There are many studies from Japan, there are studies from Italy, but there are no studies conducted in the US so this is the first study that shows a protective effect of coffee in liver cancers in the US populations.
But haven’t tests on animals shown that high quantities of caffeine can be carcinogenic?
More and more studies show that coffee consumption actually reduces cancer risk. There’s another study that’s presented here, I believe maybe tomorrow, that found a protective coffee in relations to colorectal cancer.
Do you know how this protective effect works?
At this time I don’t think people know. There are close to 100 compounds in coffee. A lot of animal studies, lab studies, try to identify which compound is actually protective but I don’t think there is a definite answer to that.
What is the recommended daily coffee intake based on this?
Based on our data, one to three cups per day are associated with a 29% decreased risk of hepatocellular carcinoma. If you drink four or more cups it’s a 49% risk reduction, which is substantial.
Is there an upper limit on how much one can consume before it’s detrimental?
No, based on our data it looks like it’s linear but we don’t have the upper limit because once you reach four or more cups per day there are not that many people in the study anymore.
Were your findings similar to the Italian study, even though there is a greater consumption of espresso?
Yes. In general most studies found that it’s coffee, whether it comes from regular coffee or from espresso, it’s associated with reduced risk.
What should the average person on the street take from this?
For those who are especially at high risk of liver cancer, those with chronic infections of hepatitis B, hepatitis C, have type 2 diabetes, and you already drink coffee, do not stop because I don’t think the side effects of coffee compared to what the benefit that you gain is high. For those who never drank coffee before, you might want to consider the pros and cons of starting drinking coffee.
What about decaffeinated coffee?
Based on the data that we have, we have a limited number of people who just drink decaf, so what we can see the protectiveness is among the regular coffee drinkers, the caffeinated one, but probably just because we don’t have enough numbers to look at the decaffeinated coffee only.
What about other caffeinated drinks?
We also have the data on caffeinated drinks but we didn’t see any protective association with caffeinated drinks. So whether it’s the caffeine in the coffee that’s protective we don’t know based on this data. It seems like it’s not.
Is coffee even protective in those with liver damage?
Yes, although we don’t have a large number. We have a subset of people that we have the data on the hepatitis B and C infection status but we also found that coffee is protective in infected people.