Greater Scores for Dietary Fat and Grain Quality Components Underlie Higher Total Healthy Eating Index–2015 Scores, While Whole Fruits, Seafood, and Plant Proteins Are Most Favorably Associated with Cardiometabolic Health in US Adults

BACKGROUND: High-quality diets reduce the risk of cardiometabolic and other chronic diseases. The dietary components that distinguish higher from lower quality diets, and their associations with health, have not been fully investigated. OBJECTIVES: This study aimed to assess the component scores that underlie differences in total Healthy Eating Index (HEI)–2015 scores, quantify fatty acid (saturated, monounsaturated, polyunsaturated) intakes that comprise Fatty Acids component scores, and assess associations between component scores and cardiometabolic risk factors. METHODS: A cross-sectional analysis of data from the NHANES (2001–2016) was conducted. Total and component HEI-2015 scores were assessed in adult (≥19 y) participants who provided one 24-h dietary recall (n = 39,799). Survey-weighted mean component scores by quartile of total HEI-2015 score were determined. Regression analyses were conducted to assess fatty acid intakes across quartiles of Fatty Acids component scores. Separate regression analyses were conducted to assess associations between component scores and cardiometabolic risk factors, after adjusting for demographic characteristics and health behaviors. RESULTS: Scores for components related to dietary fat (Fatty Acids, Saturated Fats) and grain quality (Whole Grains, Refined Grains) accounted for the greatest differences in HEI-2015 scores. Higher Fatty Acids scores were primarily composed of lower saturated and greater polyunsaturated fat intakes. Whole Fruits, and Seafood and Plant Proteins, were most favorably associated with cardiometabolic risk factors including anthropometric measures (P < 0.001), systolic blood pressure (P < 0.01), glycemic markers (Whole Fruits only, P < 0.01), and HDL cholesterol and triglycerides (Seafood and Plant Proteins only, P < 0.001). CONCLUSIONS: Average diet quality in US adults is suboptimal. Higher quality diets are primarily distinguished by the types of fats and grain-based foods that are consumed. Interventions targeting dietary components that are most favorably associated with cardiometabolic risk factors—whole fruits, seafood, and plant proteins—may have the greatest impact on disease risk.