A cup of cancer prevention? News about coffee and cancer

A recent study found that drinking coffee might be protective against colorectal cancer.  In the Israeli-based Molecular Epidemiology of Colorectal Cancer study, the coffee consumption patterns of 5,145 individuals who had been diagnosed with colorectal cancer were compared to 4,097 individuals who lived in close proximity and were roughly of the same age, gender and ethnicity, but did not have colorectal cancer.  The study analyzed the amount and types of coffee consumed (e.g., boiled, espresso, filtered, instant, and decaffeinated) from questionnaires that were completed within 6 months of the cancer diagnosis from the cancer survivors and during a similar time period from the matched controls.

The results showed that when individuals who drank less than 1 cup of coffee a day were compared to those who drank 1 to 2 cups per day, coffee drinkers had a risk of colorectal cancer that was 22% lower.  Moreover, heavier coffee drinkers (i.e., those who drank more than 2.5 cups per day) had a risk that was even lower (54%).  Associations seemed just as strong for decaffeinated coffee as for coffee with caffeine, though coffee that was boiled seemed to be more protective.  The scientists who completed this study postulate that boiled coffee may offer more protection because it has higher levels of some antioxidants. 

What does this information mean to you, or how can you use it?

Case control studies, such as this one, are helpful in “getting the field moving,” but the data that they provide should be interpreted with caution since the study design can introduce some factors that unduly influence the findings (“bias”).  In this case, colorectal cancer survivors may have cut back on their coffee consumption after diagnosis, either because they felt it was not good for them, or perhaps because it interacted with the treatments they received and caused side effects, like nausea, stomach upset, or diarrhea (all of which are possible with a diagnosis of colorectal cancer).  Cancer survivors instead should look for evidence from reviews and meta-analyses that combine the results of several studies together (including those from cohort studies which are much more rigorous than case-control studies) in order to “make more sense” out of study data.  A few months ago, the World Health Organization did just that.  

A team of 23 scientists from around the world reviewed more than 1,000 studies that explored relationships between coffee consumption and cancer. They found solid evidence that coffee reduced the risk for both endometrial cancer and liver cancer.  In addition, while their findings do not show protection for other cancers, the data also show that coffee does not increase risk.  However, none of these studies looked specifically at risk in cancer survivors.  Therefore, while it may be a bit too early to start “tanking up” on coffee with the hope that it will protect you from getting another cancer, there certainly isn’t a reason to avoid it.  Enjoy!






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