Can Coffee Protect Against Common Cancers?
Two New Studies Show Coffee Guards Against Liver and
Two separate studies, reported in the Feb. 16 issue of The Journal of the National Cancer Institute, examined the impact of coffee drinking on cancer risk.
Is Decaffeinated Coffee Really Best?
In the Harvard study, researchers examined data from two large, ongoing health trials involving 134,000 people. The participants were questioned about their coffee, tea, and caffeine consumption at different time periods over the course of 15 years.
Researcher Karin B. Michels, ScD, and colleagues found no association between consumption of caffeinated coffee or tea and colorectal cancer risk. But people who regularly drank two or more cups of decaffeinated coffee a day had about half the rate of rectal cancer as people who never drank decaffeinated coffee.
Michels tells WebMD that she initially thought the apparent protection could be explained by the fact that the decaffeinated coffee drinkers tended to have healthier lifestyles than the people who drank caffeinated coffee. But tea drinkers in the study also tended to have healthier habits, but had the same cancer risk as people who drank caffeinated coffee.
Even though she says now she believes that decaffeinated coffee may have unique cancer-fighting benefits, the researcher is not yet recommending that people switch from high-test to low.
"I would definitely like to see more studies that focus on decaffeinated coffee," she says.
Coffee and Liver Cancer
The second study, reported by researchers from
The researchers reported that people who drank coffee every day or almost daily had about half the liver cancer risk as those who never drank coffee. The more coffee people drank the lower their risk. And the protective benefits appeared to extend to those with chronic hepatitis C and B infections. They are at very high risk for developing liver cancer.
The study did not distinguish between caffeinated and decaffeinated coffee consumption, because few Japanese people drink decaffeinated coffee.
Nutritional epidemiologist Nancy Potischman, PhD, tells WebMD that the fact that liver cancer is common in
She also found it compelling that the more coffee people drank the more they seemed to be protected from liver cancer.
"That is a good indication of a real effect and not just something that is seen by chance," she says. "As an epidemiologist I always want to see more evidence, but these findings are very compelling."
For a nation fueled by Starbucks, studies suggesting that coffee drinkers may be at decreased risk for several major diseases, including Parkinson's and diabetes, is welcome news.
WebMD even recently reported on two studies from The Journal of the National Cancer Institute showing that coffee may significantly lower the risk of colon and liver cancers.
But there is also evidence that coffee may increase the risk of heart disease for some, and a new study from
Researchers from the
The findings are reported in the June 1 issue of the American Journal of Clinical Nutrition.
The researchers had already linked coffee drinking to increased indicators of inflammation, one of the key mechanisms to the development of heart disease. And they have also reported that combining coffee with cigarette smoking seems to be much worse for the heart than smoking alone.
"The evidence regarding coffee is far less conclusive than it is for smoking," study researcher
Previous studies evaluating coffee's role in promoting high blood pressure and heart disease have been conflicting. Though some suggest a strong link, others have found no link at all or even a health benefit to coffee drinking.
The latest research by Vlachopoulos and colleagues included 228 healthy adults whose average age was 41. The researchers used food-frequency questionnaires to determine how much coffee each study participant drank. They took into account whether participants drank instant coffee, brewed coffee, Greek-type coffee, cappuccino, or filtered coffee. They analyzed the data to account for each cup of coffee containing 80 milligrams of caffeine.
They also measured blood vessel wall abnormalities -- wall stiffness, the inability to expand and contract and a sign of unhealthy blood vessels.
Compared with people who did not drink coffee, people who drank two or more cups of coffee a day showed more abnormalities in blood vessel function. Blood vessel stiffness is an indictor of heart disease risk. The association remained strong even after taking into account other heart disease risk factors like smoking, obesity, and age.
But nutrition researcher Alice Lichtenstein, DSc, says the lifestyle differences between the coffee drinkers and non-coffee drinkers were so great that it would be difficult for the researchers to take these into account.
Lichtenstein is a senior scientist and director of the Cardiovascular Nutrition Laboratory at
In the study, people who drank two or more cups of coffee a day were almost nine times more likely than non-coffee drinkers to smoke cigarettes. They were also 2.5 times as likely to be obese. In general, people who drank no coffee also tended to be younger than those who drank coffee.
Age, cigarette smoking and obesity are three risk factors for heart disease. "It is more likely that heart disease risk is determined by a number of dietary and lifestyle components together, rather than individual foods," she tells WebMD.
Moderation Is Key
Lichtenstein agrees that as a whole, the research on coffee and health remains inconclusive. She adds that java junkies can probably relax if they drink coffee in moderation and reserve the cream and sugar-laden specialty coffees for special occasions.
While coffee itself has no calories, the "tall" version of, say, a double-mocha latte with whipped cream can contain more calories, fat, and sugar than a typical fast-food meal.
Vlachopoulos says it is increasingly clear that coffee consumption is an important risk factor for heart disease when combined with smoking.
"The message to smokers would be to stop, and if they can't stop they shouldn't drink coffee," he says.
SOURCES: Charalambos, V. American Journal of Clinical Nutrition, June 2005; vol 81: pp 1307-1312. Charalambos Vlachopoulos, MD, department of cardiology, Hippokration Hospital, School of Medicine, University of Athens, Greece. Alice Lichtenstein, DSc, senior scientist, director, Cardiovascular Nutrition Laboratory,
*looks at her 5th cup of coffee and sighs* Damn .. I need to cut back ..