Could a Coffee a Day Keep the Doctor Away?

Doctor poses for photo

Photo of Tania Carreón-Valencia, MS, PhD, by Cindy Starr/Mayfield Clinic.

A study published this month in the American Journal of Clinical Nutrition suggests that regular consumption of coffee and tea can protect you from glioma, the most common type of malignant brain tumor. Tania Carreón-Valencia, MS, PhD, an epidemiologist with the UC Brain Tumor Center and Assistant Professor in UC’s Department of Environmental Health, answers questions about the study and what its findings mean.

Q: Please tell us about this intriguing study, known as the Prospective Investigation into Cancer and Nutrition (EPIC). Dr. Carreón-Valencia: Researchers in Europe followed a very large group of people for a period of about eight and a half years. Researchers gave participants a questionnaire and asked them a number of questions about diet, food, occupational factors and environmental exposures. They also took blood specimens. Using a food-frequency questionnaire, which asked questions about food and liquid intake, researchers determined how much coffee and tea the participants consumed. At some point they determined how many participants had developed brain tumors. They compared the habits of those who developed brain tumors with the habits of those who did not and found that what differed was the consumption of coffee.

Q: What exactly did the researchers find? Dr. Carreón-Valencia: They found that people who consume more than 100 milliliters of coffee or tea per day — which is about 3.5 ounces, or half a cup — have a lower risk of developing gliomas. They only found this for glioma, however. The beverages did not offer protection against meningioma, a type of benign brain tumor. But for glioma, they found caffeine to have a protective effect that was also statistically significant. In short, these findings are not likely to be due to chance.

Q: Why would coffee and tea offer this protection? Dr. Carreón-Valencia: There are a few mechanisms that help explain why coffee and tea intake might be protective. First, the researchers speculate that it’s possible that the coffee is not actually preventing the development of the tumor, but that it is inhibiting the tumor’s growth. Researchers have previously found that when they apply caffeine to glioblastoma cells in vitro – in a laboratory – they are able to slow the invasive growth of these cells.

Second, the researchers talk about another mechanism that could be at work, a DNA repair protein. Certain components in coffee have been shown to trigger DNA repair activity in rat livers. Third, the researchers say that coffee has antioxidant capacity – the capacity to scavenge free radicals – and that it is actually greater than any single fruit or vegetable. That was surprising to me.

Q: If drinking half a cup of coffee is protective, is drinking more coffee even better? Dr. Carreón-Valencia: This actual research finding did not reveal a dose-response effect. When they divided the participants into different levels of coffee intake, they did not see an association. Only when they divided the group into those who drank more than 100 ml a day and those who drank less than 100 ml a day did they see a difference. I don’t know exactly what that means. But certainly that was interesting. This contrasted with an earlier U.S. study that did find a dose response, which was what you might expect: the higher the coffee intake, the lower the risk. We should keep in mind that the European study only looked at the volume of coffee consumed, not other agents or the amount of caffeine that was present in the coffee. Coffee can be brewed differently, and cultural customs – such as coffee strength – vary by country. One might drink more coffee, for example, but that might not necessarily equate with more caffeine intake. Coffee created through the force of hot, pressurized water is more concentrated than classically brewed coffee. A small cup of espresso will have much more caffeine than a large cup of filtered coffee.

Q: What about decaffeinated coffee? Dr. Carreón-Valencia: The researchers did not ask about the consumption of decaf coffee, and therefore did not measure it. Most of the coffee that is consumed in Europe is, in fact, caffeinated.   Q: Will this study inspire additional research into the benefits of specific foods and beverages? Dr. Carreón-Valencia: Absolutely. There are other studies that have looked at other food-related factors such as diet and the consumption of nitrates and nitrites that are found in cured meats, certain vegetables and beer. Cured meats have the higher content. Studies have found a higher risk of certain brain tumors with consumption of these foods, although the association hasn’t been consistent in the studies.

Q: Should people who do not drink coffee start? Dr. Carreón-Valencia:  Not yet. Because even though coffee appears to be protective against liver cancer as well, I would be cautious about recommending coffee at this point for those who dislike it. Coffee may be a reproductive risk factor for pregnant women. Furthermore, even a study as big as this, which shows some trends, is not completely conclusive. The study noted that coffee and tea drinkers tended to be older, more educated, current smokers and slimmer. Thus, coffee is sometimes associated with other habits. So other factors might also be involved.

Q: What is the UC Brain Tumor Center doing to help find definitive answers? Dr. Carreón-Valencia: What we need is a huge study involving thousands of people to study whether coffee or other factors reduce the risk of glioma. That is why we are participating in larger studies. The UC Brain Tumor Center is working with the Case Western Reserve University, the Ohio State University and the Cleveland Clinic in a larger study of brain cancer risk factors. I’m also a member of the Brain Tumor Epidemiological Consortium, which is trying to pool together data from different studies.

Q: What does the study suggest about the overall role of diet? Dr. Carreón-Valencia: We don’t know what the effect of diet is yet on cancer. There are studies that show that certain food intake reduces the risk of cancer, but are not certain. My recommendation is for people to eat a balanced diet that includes lots of fruits and vegetables and in general follows the USDA recommendations for a balanced diet – the food pyramid.

Q: Do you drink coffee? Dr. Carreón-Valencia: I do. I am having my coffee right now.

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