Is nutrition research dependable? Stanford’s John Ioannidis weighs in
John Ioannidis, MD, a Stanford professor of medicine and of health research and policy, is ready for a change in the way nutrition research is conducted. Too often, he says, nutrition studies today are flawed or biased, and their conclusions end up relaying fairly unreliable results.
So in a perspective piece published today in Advances in Nutrition, Ioannidis outlines what he hopes to see in the future of nutritional research and the changes he believes will steady the somewhat shaky structures of the average nutrition study.
I recently chatted with him to find out more about his vision for the field, and how he sees it coming to fruition.
There seems to be a lot of contradictory findings related to nutritional research. What do you think is the main reason for that?
We still largely depend on nonrandomized studies to assess questions of nutrition. These studies are notoriously incapable of giving reliable answers due to confounding factors. In nutrition, the situation is made even worse because our ability to measure diet is still limited in accuracy, and recall biases, in which study participants remember something incorrectly, can be severe. In addition, dietary intake of a single nutrient probably has small or even tiny effects on major health outcomes, even if diet as a whole is important. Therefore, any potential finding is largely shaped by the noise from errors and biases of observational studies.
What is the biggest inherent problem in the current designs of nutritional studies, and how do you think it could be remedied?
The biggest problem is that the vast majority of studies are not experimental, randomized designs. Simply by observing what people eat — or even worse, what they recall they ate — and trying to link this to disease outcomes is moreover a waste of effort. These studies need to be largely abandoned. We’ve wasted enough resources and caused enough confusion, and now we need to refocus. Funds, resources and effort should be dispensed into fewer, better-designed, randomized trials.
How feasible would it be to implement a new approach to nutrition research in which resources are pooled for larger studies and a handful of major questions are pursued?
It should be very feasible to implement this new approach. The cumulative cost would not be higher; it may even be less expensive. We would ask fewer questions, but we would get far more solid answers. We may be able to start getting some reliable evidence to inform nutritional guidelines rather than have them be battlefields of opinion.
Photo by Brooke Lark