Yet another article about a possible link between wine and breast cancer is in the news, and as usual it is being widely quoted without any critical analysis or perspective. The article in question, a review of previously published studies, estimates that even a glass of wine per day increases risk of breast cancer and estimates that 1-2% of all breast cancer cases are attributable to light drinking alone. Rather than pick apart the article item by item, which would take all day since there are so many issues, I will highlight a few important things.
First, there are fundamental problems with the way that these types of studies are done, and reviewing them simply magnifies the underlying mistakes. Here’s the thing: in order to know if for example a glass of wine per day affected breast cancer risk, you would have to follow a large population of women who drink only wine, only a glass per day, every day, rarely more, rarely anything other than wine, and rarely not having a drink; this would need to be compared to a similar population who never drink, another who only drink beer, and so forth. But most people have mixed drinking patterns, they under-report their true level of drinking, and there is simply no reliable way to get any meaningful information. All we really know is that heavy drinking is bad.
Secondly, there are some populations of women in France who have traditionally consumed wine in moderate amounts and in a regular pattern. Their incidence breast cancer is dramatically lower than that of nondrinkers.
Third, breast cancer is nowhere near the leading cause of premature death in women; heart disease is far and away the biggest threat. It is well established that moderate wine consumption lowers heart disease risk, the net effect being overall reduction in risk of premature death.
Moderate wine consumption is also associated with lower odds of Alzheimer’s disease, osteoporosis, diabetes, and measurably improves quality of life and well-being. Wine drinkers outlive nondrinkers by about 5 years on average, and for most even if there is a fractional increase in breast cancer risk, the smart choice favors having a glass of wine with dinner and not stressing over it.