I had just finished my first cup of joe yesterday—a morning ritual of great importance to me—when I stumbled upon a Reuters story that said there was no link between coffee consumption in men and prostate cancer. Coffee, in this case, was vindicated, but I wasn’t aware that it had been a suspect, at least not for several years. A number of recent studies have shown that coffee—and most likely caffeine—has a protective effect against certain types of cancer; others show no association between coffee and a broad range of cancers. Since I consume so much of the stuff, I thought I’d best do a little digging, and I must say that I was pretty surprised by what I learned.

Let me say a couple things right off the bat, especially for you folks who don’t make it to the end of blog posts. If you’re a woman and pregnant, or a mother who is breastfeeding, you should drink no more than two cups of coffee per day (8oz each — so no more than 16oz), and quite possibly none at all. Studies associate coffee consumption during pregnancy with higher risk of miscarriage, low birth weight, and certain birth defects—cleft palate is one. Caffeine is transferred from mother to baby during breastfeeding. While adverse effects are unlikely, there are reports of irritability and sleep interruption in nursing infants. The American Academy of Pediatrics recommends limiting caffeine consumption to three cups of coffee, caffeinated tea, or soda per day. Yes, that had nothing to do with cancer, but making sure moms don’t walk away from a coffee story with the wrong message is important.

On to the good news about coffee. Cancer Epidemiology, Biomarkers & Prevention, a journal of The American Association for Cancer Research, recently published a study that found that people who drank four or more cups of coffee a day were 39% less likely to develop two types of head and neck cancer. The study was associative—it did not attempt to prove that coffee prevents head and neck cancer—and compiled data from nine previous studies. The association between significant coffee consumption and significantly lower risk for head and neck cancer is strong, however. By the way, “head and neck cancer” is a medical category that does not include brain cancer.

Coffee may reduce the risk of the deadliest form of prostate cancer, according to a Harvard Medical School study involving 50,000 men over 20 years. Men who drank six or more cups a day (6oz cups) had a 60% lower risk of developing advanced prostate cancer. The study did not find that coffee prevents prostate cancer. Rather, consuming large amounts of coffee is associated with a significantly lower chance of getting the most advanced form of this cancer.

A number of recent studies have shown other potentially positive effects of coffee consumption: lowered risk of type-II diabetes, dementia, and Parkinson’s disease. Again, this is potentially causal; there’s an association between increased coffee consumption and lowered risk, but it doesn’t mean that drinking more coffee will reduce your risk for these diseases.

And now for coffee’s dark side. A 1981 study by the Harvard School of Public Health showed a strong relationship between coffee consumption and significantly increased risk of pancreatic cancer. The New York Times reported at the time that statistically, the “data showed that a person who drank two cups of coffee a day had twice as great a risk of pancreatic cancer as a person who did not drink coffee. For a person who drank more than five cups, the risk was more than three times that of the nonuser.” Frightening news, particularly if the relationship is causal, but there was at least one significant problem with the study. Harvard scientists used hospitalized patients as their control group. In other words, they explored coffee-drinking habits among people who were already sick; the study did not look at whether there was an association between coffee consumption and increased pancreatic cancer risk among healthy people. A study published in Cancer Epidemiology, Biomarkers & Prevention in 2001, which looked at coffee and alcohol consumption and the risk of pancreatic cancer, found that among initially healthy people “Neither coffee nor alcohol intakes were associated with an increased risk of pancreatic cancer”.

Roasting coffee creates at least one known carcinogen: acrilamyde. While it might seem counterintuitive, the highest levels are in medium roast, and the lowest are in dark roast. And carcinogens from non-organic coffee farming and preparation might also be present in the products we consume—a strong argument in favor of organic coffee.

Altogether, I don’t see any reason to change my four-cup-a-day habit. Granted, I’m addicted—I readily admit it—but I’m also pretty concerned about my health. The evidence that I’ve been able to come up certainly isn’t leaning against coffee when it comes to cancer; the opposite seems to be the taste. Add to this the non-cancer-related benefits of coffee drinking mentioned above and my love for coffee’s taste and smell (when it’s good coffee, prepared correctly of course); well, you get it.

Oh, there goes my kitchen timer. Gotta run, folks — my coffee’s ready!*

*IMPORTANT NOTE: The working conditions on coffee plantations are often abysmal, and we know that pesticides contain carcinogens. If you’re a coffee drinker, buy only fair trade, organic coffee, and ask for it whenever you eat—or drink—out.  Also, be kind to Mother Earth. If you get your dose at a cafe each day, bring along a mug, and tell places that sell coffee that they should use recycled & recyclable containers and tops for their products.