Government Dietary Guidelines: Uncertain Science Leads to Questionable Public Health Policy

Abstract

The US Department of Agriculture has issued dietary recommendations for more than a century, and during that period the health, longevity, and nutritional status of Americans improved markedly. Before the release of the first Dietary Guidelines for Americans (DGA) in 1980, the recommendations were based on rigorous science and simply offered general information on choosing foods and beverages to prevent deficiencies and maintain health. Yet with each subsequent version, the DGA became increasingly complex, prescriptive, and nutrient-focused (as opposed to food-based) despite an ever-increasing uncertainty and lack of credibility in the supporting evidence. This review examines the historical record of the development of the DGA and demonstrates that current recommendations were based on biased, implausible anecdotal evidence and that rigorous contrary research and the diversity of expert opinions on diet–health relationships were ignored. It concludes with an examination of the unintended negative public health consequences of founding policy on uncertain science.