Like so many of you, my wife and I like to start off our day with a cup of steaming black coffee. Then, before dinner, we catch up on the day’s events during “happy hour” (I love a cold beer, or classic martini à la James Bond, while she usually prefers a glass of white or red wine).
Our daily ritual is predicated on the belief that, when consumed in moderation, both beverages provide pleasure and, especially in the case of alcohol, may provide a significant health benefit. Yet, when it comes to cancer risk, there appear to be pros and cons associated with each.
Let’s examine the evidence, starting with coffee.
As reported last week on CTV, a just-published study of 6,000 Swedish women between the ages of 50 and 74 found a 20% decrease in breast cancer among heavy coffee drinkers (five or more cups per day). Moreover, the researchers found that heavy consumption of non-filtered “Swedish-style” coffee mainly decreased (by 57%) the risk of developing the more aggressive type of breast cancer that is not driven by estrogen.
Since coffee contains several substances, including caffeine, that decrease circulating estrogen levels, a preferential drop in estrogen-driven breast cancer might have been predicted, but this was not found.
Can we believe these results? Yes and no. A significant decrease in breast cancer risk among heavy coffee drinkers was also found in the large Nurses’ Health Study , while an equally large Swedish study published two years ago by different researchers at the same (Karolinska) institution as the current study, found no association between heavy coffee drinking and decreased breast cancer risk.
There is also disagreement over whether lesser amounts of coffee confer protection against breast cancer.
For example, a recently-published French study involving over 67,000 subjects, found no decrease in the incidence of breast cancer in women who drank, on average, 2.2 cups of coffee per day.
In contrast, a meta-analysis of 59 published epidemiological studies carried out by Chinese researchers found that, compared to non-coffee drinkers, low to moderate coffee drinkers had an 11-13% decrease in overall cancer risk, including breast cancer, while heavy coffee drinkers had an 18% decreased risk. Combining all of the data, they determined that, for every cup of coffee consumed per day, there was a 3% reduced risk of cancer (including breast, bladder, oral cavity, esophagus, pancreas, liver, colon, pancreas and prostate).
And what about alcohol?
It has been firmly established, both in large populations and in studies of twins, that those who drink spirits (wine, beer or hard liquor) in moderation (up to 2 drinks daily for men and 1 drink daily for women) live longer, on average, than non-drinkers, mainly as a result of a significant reduction in cardiovascular disease.
When it comes to cancer, there are no data to indicate whether low to moderate alcohol consumption is ever beneficial. Heavier consumption is another matter, however. Recent large population studies have shown unequivocally that exceeding 2 drinks per day in men and 1 drink per day in women increases overall cancer rates in males by 10% and in females by 3%, and breast cancer rates by 5%. Not surprisingly, the greatest increase in alcohol-related cancers in both sexes occurs in the oral cavity, esophagus and liver.
With regard to alcohol and breast cancer, the American Cancer Society states: “Compared with non-drinkers, women who consume 1 alcoholic drink a day have a very small increase in risk. Those who have 2 to 5 drinks daily have about 1½ times the risk of women who drink no alcohol….The American Cancer Society recommends that women limit their consumption of alcohol to no more than one drink a day.”
So there you have it. Moderation wins. A cup of coffee in the morning and a single beer, martini, or glass of wine at happy hour appear to do virtually no harm at worst, and are beneficial to our health at best. I’ll drink to that!