TAKE NUTRITION STUDIES WITH A GRAIN OF SALT

THE EPIDEMIOLOGY OF FOOD AND DRINK IS A MESS.

- RONALD BAILEY

COMB THROUGH ENOUGH nutrition research, and you can find a study confirming or rebutting nearly every belief you may hold about how specific nutrients affect your health. "Meat Increases Heart Risks, Latest Study Concludes," reported The New York Times in 2020. A year earlier, the Times ran this headline: "Eat Less Red Meat, Scientists Said. Now Some Believe That Was Bad Advice." 

Pick a different food group and find a similar contradiction. “Moderate Drinking Has No Health Benefits, Analysis of Decades of Research Finds,” reported the Times in April 2023. Two months later, Forbes declared: “Light And Moderate Drinking Could Improve Long-Term Heart Health Study Finds— Here’s Why.”

These headlines were not misrepresentations. Nutritional epidemiology is, by and large, what Stanford University biostatistician John Ioannidis calls a “null field”: one where there is nothing genuine to be discovered and no genuinely effective treatments exist.

“I think almost all nutrition studies that pertain to the effects of single nutrients on mortality, cancer, and other major health outcomes are null or almost null,” says Ioannidis. “Even the genuine effects seem to have very small magnitude in the best [and] least biased studies.”

When it comes to public policy, most nutritional epidemiologists are unclothed emperors ordering the rest of us around or lobbying lawmakers to do it for them.

This doesn’t mean you can eat an entire pizza, a quart of ice cream, and six beers tonight without some negative health effects. (Sorry.) It means nutritional epidemiology is a very uncertain guide for how to live your life and it certainly isn’t fit for setting public policy.