Captive audience? Andrew Lichtenstein/Corbis via Getty Images
The science of nutrition has been with us for a long time. So why are there so many apparent uncertainties over dietary advice today?
The nutrients in our food may have inherent effects on metabolism, but proving so requires tightly controlled experiments in lab-like conditions that are difficult to conduct in groups of healthy people. Evaluating how diet influences diseases or defining the optimal diet for good health, where effects are small and long-term, can only occasionally be done under such conditions.
Instead, most dietary studies involve large-scale observational research to identify associations…
