Coffee, Tea, and…Cancer?

Diverse theories on coffee and tea and our health have many of us wondering whether to quit, cut back, or keep sipping. Current research provides some interesting answers about the impact of your daily fix.

Millions of us enjoy a cup—or several—of coffee or tea each day. Habit, tradition, ritual, and big business, these beverages are ubiquitous, considered by imbibers to be everything from a treat to a vital necessity. In spite of the popularity of coffee and tea, however, debate continues as to whether they’re good or bad for our health. The issue becomes more complicated when we question the health implications of coffee and tea in regard to specific health concerns such as cancer. Throughout the respective histories of coffee and tea, from their origins in northern Africa and the Far East to their contemporary place in our twenty-first century diet, aficionados have been eager to believe that each has medicinal properties. There are two popular legends surrounding coffee’s discovery, each in homage to the beverage’s effects on body and mind. In one story an Ethiopian goatherd noticed that his animals became particularly lively after nibbling on berries from a certain tree. The other tale recounts the story of a man named Omar, who—when near starvation—had a vision leading him to a coffee tree, where he ate revitalizing berries. Tea’s origins are even more firmly health-centered, as tea leaves were used as a medicine before they were brewed for drinking: it’s reported that prehistoric inhabitants of the Himalayan region chewed tea leaves for their invigorating effects and also rubbed them on wounds to encourage healing[1]

By the seventeenth century, trade routes among Europe, Asia, and Africa allowed coffee and tea’s popularity to grow in Britain as well as on the Continent. Coffee was embraced by scientists and intellectuals at this time—conveniently, the Age of Reason—for its stimulatory effects, providing a sobering alterative to the most common beverage at the time, beer. In addition to mental clarity, proponents of coffee claimed that it could relieve such maladies as sore eyes, headaches, and scurvy and even prevent miscarriages. The growing popularity of tea gave rise to purported health benefits as well, including general wellness and longevity, with some physicians encouraging heavy consumption (“as much as the stomach can take,” wrote one doctor). More specifically, tea was thought to have natural antibacterial properties, which might reduce the risk of water-borne diseases such as dysentery. Though these therapeutic claims for both coffee and tea were often challenged, the beverages’ popularity (whether for taste, stimulatory effects, or presumed health benefits) has kept our cups full ever since, allowing questions about how coffee and tea affect our health to also persist.[1]

The Big C: Caffeine

Though our beloved mugs of coffee and tea seem firmly established in our culture, there remains a level of suspicion about potential harmful effects of the signature ingredient in many of our favorite cups: caffeine. Caffeine tends to be discouraged for children, adolescents, the elderly, and people with hypertension, and it is recommended only in small amounts for women who are pregnant, as these groups may be more vulnerable to coffee’s potential harmful effects.[2] But trying to pin down what these harmful effects are, and to what extent we should be concerned for our health, makes it clear that there are still questions about how caffeine affects us.

One definitive concern about consuming too much coffee or tea is that caffeine is a diuretic, making dehydration a risk. Other areas of concern associated with caffeine—particularly in large quantities and when consumed at the wrong time—include sleep disturbances, adverse hormonal reactions, and hitting lows in energy and mood as effects dissipate. Despite these concerns, however, evidence seems to suggest that, in general, for those of us who aren’t overly sensitive to stimulants or don’t fall into any of the risk categories mentioned above, drinking moderate amounts of coffee (three to four cups a day) is quite safe.[3]

The Cancer Connection

According to the American Cancer Society, studies have failed to prove a link between caffeine consumption and increased risk for cancer.[4] In fact, evidence is largely in favor of coffee and tea consumption where cancer is concerned, with many findings indicating a protective effect in relation to several cancers.

The health benefits of coffee and tea are often explained by the beverages’ antioxidant properties, which may protect from damage caused by free radicals (unstable molecules that have been associated with the development of cancer). But healthcare professionals caution that these benefits should not be blown out of proportion. “These beverages are not the ‘magic bullet,’” says Sally Scroggs, RD, LD, senior health education specialist in the Department of Cancer Prevention at the University of Texas M. D. Anderson Cancer Center. “I do not want people filling up on coffee and tea and thus eliminating other nutrient-dense foods.” Instead, she says, moderation should remain a principal dietary guideline, with coffee and tea consumption part of a nutritionally sound eating plan.

Current Research

Coffee
If asked which half of the coffee-tea duo was more likely to have an adverse impact on health, many of us might choose coffee; the brew is often regarded with more apprehension and receives the bulk of the bad press, whereas tea is commonly considered the more innocuous and thus healthier alternative. Though tea certainly has its attributes (discussed later), research in cancer seems to indicate that much of coffee’s bad-boy image is unwarranted; in fact, studies show that coffee may have protective effects in certain cancers:

When it comes to protection from liver cancer, coffee may have a protective effect. A study by Italian researchers in 2007 found a possible link between coffee consumption and a reduced risk of liver cancer. Their findings, based on data from southern Europe and Japan, showed not only a 41 percent reduced risk of developing liver cancer for coffee drinkers but also a rise is protective effect with increased coffee consumption: for each additional cup of coffee consumed per day, the risk of liver cancer was reduced by 23 percent.[5]

Coffee drinkers may also be able to reduce their risk of colon cancer. Japanese researchers reported in 2007 that Japanese women may lower their risk of the disease with moderate coffee consumption: those who regularly drank more than three cups per day had a significantly reduced risk of developing colon cancer compared with those who rarely drank coffee.[6]

Renal cell carcinoma (kidney cancer) risk may also be reduced among coffee drinkers. A recent study found that for individuals who drink three or more 8-ounce cups of coffee per day, risk of the disease may be reduced compared with those who drink only one cup per day. Although the observed reduction in risk noted in this study was not large enough to be statistically significant, these researchers did note that consumption of coffee, as well as tea, is unlikely to increase risk for renal cell cancer.[7]

Tea
In both green and black varieties, tea may help protect your body against several forms of cancer as well as enhance your overall health. According to the National Cancer Institute, the antioxidants found in tea (called catechins) may inhibit the growth of cancer cells.[8] And because the tradition of tea drinking dates back as far as 5,000 years in India and China, the research community is understandably curious about the scientific link between tea and health, with cancer-related health being a particular area of interest. Following are some of the findings made to date:

Tea has shown a protective effect against ovarian cancer. In 2005 researchers in Sweden reported that women who drank tea had a reduced risk of developing the disease compared with those who seldom or never drank tea—up to 46 percent with two or more cups per day.[9]
Tea may share with coffee the potential to reduce the risk of kidney cancer. Research has indicated a lower risk of the disease among individuals consuming one or more 8-ounce cups per day compared with those who didn’t drink tea.[8]
Because tea contains flavonols (plant chemicals found in tea as well as in fruits, vegetables, and red wine), it may help reduce risk of pancreatic cancer, particularly among smokers—a group at increased risk of the disease. A recent study observed that individuals with high flavonol intake had a 23 percent reduced risk of developing pancreatic cancer compared with those with a low intake.[10]

Although tea may help protect against cancer, its ability to improve cancer outcomes is less certain. Green tea, specifically, was evaluated in 2006 for its association with cancer mortality. Findings from this study indicated no survival benefit for cancer patients who consumed green tea.[11]