Read meat causes cancer. No, processed meat causes cancer. OK, it’s both read meat and processed meat. Wait, genetically modified grain causes cancer (well, not really). No, aspartame causes cancer. No, this food coloring or that one causes cancer.
Clearly, everything you eat causes cancer!
That means you can avoid cancer by avoiding processed meats, red meat, GMO-associated food (no, probably not), aspartame, food colorings, or anything “unnatural.” Or so it would seem from reading the popular literature and sometimes even the scientific literature. As I like to say to my medical students, life is a sexually transmitted fatal disease that gets us all eventually, but most of us would like to delay the inevitable as long as possible and remain as healthy as possible for as long as possible. One of the most obvious ways to do accomplish these twin aims is through diet. While the parameters of what constitutes a reasonably healthy diet have been known for decades, diet still ranks high on the risk of concerns regarding actions we take on a daily basis that can increase our risk of various diseases. Since cancer is disease (or, I should say, cancers are diseases) that many, if not most, people consider to be the scariest, naturally we worry about whether certain foods or food ingredients increase our risk of cancer.
Thus was born the field of nutritional epidemiology, a prolific field with thousands of publications annually. Seemingly, each and every one of these thousands of publications gets a news story associated with it, because the media love a good “food X causes cancer” or “food Y causes heart disease” story, particularly before the holidays. As a consequence, consumers are bombarded with what I like to call the latest health risk of the week, in which, in turn, various foods, food ingredients, or environmental “toxins” are blamed and exonerated for a panoply of health problems, ranging from the minor to the big three, cardiovascular disease, diabetes, and cancer. It’s no wonder that consumers are confused, reacting either with serial alarm at each new “revelatory” study or with a shrug of the shoulders as each new alarm joins other alarms to produce a tinnitus-like background drone. Unfortunately, this cacophony of alarm also provides lots of ammunition to quacks, cranks, and crackpots to tout their many and varied diets that, they promise, will cut your risk of diseases like cancer and heart disease to near zero—but only if adhered to with monk-like determination and self-denial. (Yes, I’m talking about you, Dean Ornish, among others.)
All of this is why I really wanted to write about an article I saw popping up in the queue of articles published online ahead of print about a month ago. Somehow, other topics intervened, as did my vacation and then the holidays, and somehow I missed it last week, even though a link to the study sits in my folder named “Blog fodder.” Fortunately, it just saw print this week in its final version, giving me an excuse to make up for my oversight. It’s a study by one of our heroes (despite his occasional misstep) here on the SBM blog, John Ioannidis. It comes in the form of a study by Jonathan D. Schoenfeld and John Ioannidis in the American Journal of Clinical Nutrition entitled, brilliantly, Is everything we eat associated with cancer? A systematic cookbook review.