One study found that daily drinking coffee could cut the risk of liver cancer, while the other found no association between drinking coffee or tea, and the risk of colorectal cancer.
Coffee consumption is common throughout the world, with retail sales hitting over €54 billion. And scientists continue to explore the impact it may have on human health.
The first study, published in the 16 February issue of the Journal of the National Cancer Institute, found that people who drank coffee on a daily or almost daily basis had about half the risk of developing hepatocellular carcinoma (HCC: a type of liver cancer) compared with those who never drank coffee.
According to researchers at the National Cancer Center in Tokyo that carried out the study, the rate of liver cancer among those who never drank coffee was 547.2 cases per 100,000 people over 10 years.
Among daily coffee drinkers the rate was almost fifty per cent less, at about 214.6 cases per 100,000 people.
Of particular interest, the risk of HCC decreased with an increase in the amount of coffee consumed each day.
But the authors caution that because decaffeinated coffee is rarely consumed in Japan, and therefore no distinction was made between caffeinated and decaffeinated coffee, they were unable to determine if caffeine was responsible for the decreased risk of HCC.
" Further studies are warranted to assess whether the present results can be generalised or are representative of other populations," say the researchers.
In the second study, Karin B. Michels and colleagues at Brigham and Women's Hospital in Boston, explored the association between coffee, tea, and caffeine consumption and the incidence of colorectal cancer.
They used data from two large prospective studies (the Nurses' Health Study (women) and the Health Professionals' Follow-up Study (men)), that totalled almost 2 million person years of follow-up.
The researchers report that they found no association between consumption of caffeinated coffee or tea and the incidence of colon or rectal cancer in either group.
But suggesting the benefits of decaff consumption, study participants who regularly drank two or more cups per day of decaffeinated coffee, had about half the incidence of rectal cancer compared with those who never drank decaffeinated coffee.
The authors caution that this observed association may be due to differences in lifestyle; because drinkers of decaffeinated coffee might be more health conscious in their behaviour than those who consume caffeinated coffee.
They recommended new studies to confirm the decaffeinated vesus caffeine findings.
After being dogged in recent years by poor prices following a glut in coffee production, prices are just starting to recover for the global industry. A surge in Arabica prices recorded during the last quarter of 2004 continued into January 2005.
According to the International Coffee Organisation, most of January's Arabica transactions involved price levels of over US107 cents/lb compared to below US 70 cents/lb a year ago.