Is there anything coffee can't do? / by Methods Man

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Coffee. It’s hard not to be biased when it comes to the ubiquitous drink. Many of us, myself included, depend on the stuff to start our day, continue our day, and give us something to do when we should otherwise be working. Studies linking coffee to better health get a lot of press. A few months ago, a big splash was made when a study linked coffee consumption to lower risk of melanoma (though they failed to account for sun exposure). Now, we have coffee staving off colon cancer.

The paper, appearing in the Journal of Clinical Oncology, examined roughly 1000 individuals with stage 3 colon cancer, who had been through at least the first round of surgery and chemotherapy. Each of them filled out a detailed food-frequency questionnaire within a couple months after the initial treatment, and they were followed prospectively for cancer recurrence or death.

The majority of the cohort reported drinking 1-3 cups of coffee per day. A small number, 6%, reported taking more than 4 cups per day. Heavy coffee drinkers were more likely to be male, white, and smokers, and had a higher level of physical activity.

After around 7 years of follow-up, 35% of the patients had experienced cancer recurrence or died. Among those who drank 4 or more cups of caffeinated coffee per day, the overall risk of recurrence or death was reduced by about 50% after adjustment for confounders.

Let that sink in a minute. 50%. Has one of the most potent anti-cancer agents been literally sitting under our nose all these years? Well, as much as I’m a java fan, I might need to cool this off a bit.

First off, these patients were part of a clinical trial evaluating the role of adding irinotecan to standard adjuvant chemotherapy for colon cancer. Clinical trials recruit very specific patients - these results may not hold for your typical colon cancer survivor. 

Another issue: Food frequency questionnaires generate a ton of data - you can't possibly control for everything people eat. The authors adjusted their results for total caloric consumption, but it is possible that foods that correlate with coffee intake are the actual drivers of the relationship here. Put simply, it's just as likely that this is a biscotti effect as a coffee effect.

Finally, the big issue: What do we mean when we say coffee? Is an espresso the same as a venti caramel macchiato? Does it matter where the beans come from? How they are roasted? How much sugar you add to it? This is the central problem of dietary research, and one that can only be overcome by randomized trials.

So let’s do it. There seems to be enough data now to justify actually trying this under controlled settings. My prediction is that we won’t see a 50% reduction in recurrence of colon cancer, but we may see something. After all, coffee is a drug. A wonderful, tasty, necessary drug that goes great with pie.