Quality of Popular Diets in the United States

OBJECTIVES: 1) Evaluate the quality of popular diets in the US, and 2) model the effect of targeted food substitutions on diet quality. METHODS: Dietary data from 34,411 adults ≥20 y were acquired from the National Health and Nutrition Examination Survey, 2005–2018. Usual dietary intake was assessed using the National Cancer Institute's usual intake methodology, and the Healthy Eating Index-2015 was used to evaluate the diet quality of eleven popular diets. A diet model was used to evaluate the effect of targeted food substitutions on diet quality. RESULTS: Participants that followed a pescatarian diet pattern had the highest diet quality (65.2, 95% CI: 64.0–66.4), followed by vegetarian (63.0, 62.0–63.0), very low grain (62.7, 62.2–63.3), flexible paleo (62.3, 61.1–63.4), low grain (61.2, 60.6–61.9), low-moderate grain (59.7, 59.3–60.2), omnivorous (57.8, 57.5–58.1), restricted carbohydrate (56.9, 56.6–57.3), time restricted (55.2, 54.8–55.5), moderate protein (55.0, 54.7–55.3), and high protein (51.8, 51.0–62.7). Modeled replacement of up to three daily servings of foods highest in added sugar, sodium, and saturated fat with alternative foods led to a statistically significant increase in diet quality and a decrease in energy intake for most diets (P < 0.001 for most diets). CONCLUSIONS: Low diet quality was observed for all popular diets evaluated in this study. Modeled dietary shifts that align with recommendations to choose foods lower in added sugar, sodium, and saturated fat led to only modest improvements in diet quality but a larger reduction in energy intake. Greater efforts are needed to shift consumer perceptions away from reductionist dietary approaches that place undue emphasis on specific foods, individual macronutrients, and timing of eating, and toward healthy dietary patterns that emphasize consumption of a variety of high-quality food groups. FUNDING SOURCES: This work was supported by the Institute for the Advancement of Food and Nutrition Sciences (IAFNS) Carbohydrate Committee. IAFNS is a nonprofit science organization that pools funding from industry collaborators and advances science through the in-kind and financial contributions from public and private sector participants. IAFNS had no role in the design, analysis, interpretation, or presentation of the data and results.