For three days, Alex Jofriet drank one 8-ounce glass of milk per day. This was a big deal because he hadn’t touched the stuff in years. Jofriet has Crohn’s disease, a poorly understood chronic inflammation of the intestine. Eat the wrong thing, or even too much of the right thing, and he would pay the price: hours in the bathroom wracked with stomach pain, gas and diarrhea.
But Jofriet took the risk. He and his doctor, Shehzad Saeed, decided to set up an experiment, and Jofriet would be the only subject. For those three days, he would drink milk like he wasn’t afraid, like he hadn’t spent the past eight years negotiating a careful truce with his digestive system. He would drink milk and record how he felt on those days. How many bowel movements did he have? Was there blood in his stool? Did he have stomach pain and bloating? Then Saeed would statistically compare Jofriet’s health on the days he drank milk with the days he didn’t.
This isn’t how scientists normally answer health questions. In fact, the question itself is all wrong. Medical research happens on the scale of populations. You’re supposed to ask big questions like, “Does drinking milk cause negative symptoms in Crohn’s disease patients?” Then you’re supposed to round up a large and representative sample of patients, randomly sort them into groups, test the hypothesis using placebos or other controls, and check to see whether all the individual results yield a statistically significant aggregate answer.
This is the basic outline of a randomized control clinical trial — the gold standard of medical research and the basis of most of the medical facts we hear from doctors and read in magazines like this one. It’s the best way we know of to learn about how our bodies work (and don’t work) and what it takes to fix them.
But even the gold standard isn’t perfect. The controlled clinical trial is really about averages, and averages don’t necessarily tell you what will happen to an individual. Such a trial might tell you that, statistically speaking, milk isn’t good for Crohn’s patients. But within that sample, there might be people who didn’t have any problems drinking milk, and people whose symptoms even got better while drinking it. In the doctor’s office, one on one, what you know about average results for a population is just the beginning, not the final word.
