Why Does Nutrition Advice Always Seem to Be Changing?

It can be hard to keep up with ever-changing guidelines. Marion Nestle shares a few principles to help steer you right.

Marion Nestle
Elemental
Published in
6 min readOct 9, 2020

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Photo: Kseniya Ovchinnikova/Getty Images

Everyone eats. Everyone can claim firsthand experience and expertise. Whose experience and expertise should you trust? “Mine, of course,” is my standard (slightly facetious) answer. I can understand why people trust celebrities more than scientists or nutritionists; they feel like friends, even if the relationship is unreal. It doesn’t help that nutritionists have impenetrably confusing credentials, ranging from none beyond personal experience to years of graduate and post-graduate study.

It also doesn’t help that nutrition science is so extraordinarily difficult to do. Just think of what it would take to show whether eggs, the largest dietary source of cholesterol, raise the risk of heart disease. To achieve definitive results, you would need to put large numbers of people matched in age, gender, and risk on one of two defined diets, the same except for whether eggs are included. To make sure your study subjects stick to the diet, you would have to confine them under close supervision for expensively long periods to see whether eggs induced symptoms.

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Marion Nestle
Elemental

Professor of Nutrition, Food Studies & Public Health, emerita, NYU. Writes books about food politics; blogs at foodpolitics.com, tweets @marionnestle.