A new study in the August 10 issue of the International Journal of Cancer shows that coffee consumption decreases the risk of liver cancer.
The study, performed in Japan, involved 50,000 subjects over a period of from 7 to 9 years. The researchers questioned the subjects at the start of the study as to their consumption of coffee, green tea, and black tea. At the end of the study period, the subjects who had developed liver cancer were analyzed as to their coffee, green tea, black tea consumption as compared to those who didn’t develop liver cancer.
The authors point out in the introduction to the study that
Primary liver cancer is the third most common cause of death from cancer worldwide. The incidence of liver cancer is highest in Eastern Asia, including Japan. Although its incidence is lower in Europe and the United States, it has been increasing over the last few decades.
When the data were tabulated they showed that the group drinking the most coffee had the greatest degree of protection against liver cancer. And, those study subjects who had already developed liver disease (not cancer) at the start of the study had an even more dramatic protective effect.
Surprisingly, green tea showed no effect in terms of protection against the development of liver cancer. There were not enough subjects who drank black tea to provide a statistical determination of its protective capabilities or lack thereof.
Interestingly, the Japanese who drank the most coffee
tended to be younger and male, and were more likely to be drinkers and heavy smokers (20 cigarettes or more/day) and were less likely to have a history of liver disease.
It all goes along with the idea that somehow coffee is unhealthy, leaving only the people who don’t care about their health (the smokers and heavy drinkers) to drink it in large amounts. (Them and yours truly)
Why is coffee protective? The researchers don’t know, but can speculate.
It remains unclear which ingredient(s) of coffee is protective against liver cancer. Mutagenic and antimutagenic effects of coffee and caffeine on cultured cells of bacterial and mammalian origin have been demonstrated, but mutagenic effects would be almost non-existent at the usual levels of coffee consumption in humans. The caffeine concentration in coffee and green tea is 0.06% and 0.02%, respectively. Caffeine might not have a protective effect against liver cancer because our study indicated that consumption of green tea was not associated with the risk of liver cancer. Coffee also contains chlorogenic acid, a phenolic compound, whose inhibitory effects on chemical carcinogenesis in the liver have been demonstrated in an animal model.
We have found that coffee consumption is significantly associated with a decreased incidence of liver cancer. In addition, subgroup analysis among our subjects with a history of liver disease showed an inverse association between coffee consumption and the risk of liver cancer.
Based on my reading over the past few years, I can tell you that there are over 1000 antioxidant compounds in coffee, some 300 of which come into existence when the coffee is roasted. Coffee contains a significant amount of magnesium, which most people don’t get enough of in their regular diet. Coffee is protective against diabetes and a host of other diseases. Coffee is a natural substance, not an artificial one; it comes off the coffee tree, it’s not manufactured. I’ve never been able to determine why so many people are down on coffee.
I say drink up.