Interaction Between Meal-timing and Dietary Inflammatory Potential: Association with Cardiometabolic End Points in a 3-Month Prospective Analysis

Background Diet quality is a moderator of cardiometabolic markers. The timing of dietary intake may be an important determinant; however, previous results have been mixed. Complex mechanisms may result in an interaction between diet timing and quality. Objectives This study aimed to examine the association between fasting duration and first and last mealtime and inflammatory and lipid biomarkers. We also explored the interactions between Energy-density Dietary Inflammatory Index (E-DII) scores and meal-timing on inflammatory and lipid biomarkers. Methods This study was a secondary data analysis of a dietary intervention. Assessments occurred at baseline and 3 mo. Three unannounced 24-h dietary recalls estimated diet for calculation of E-DII scores, nighttime fasting duration, and first and last mealtime. Cardiometabolic markers were obtained from a fasting blood sample. Multiple linear regression of baseline data was used for aim 1. For aim 2, the interaction between E-DII change over 3 mo and the meal-timing metrics were used to estimate changes in cardiometabolic markers. Results Most participants (n = 95) were female (81%) and White (62%) and their average age was 46.9 ± 13.4 y and body mass index of 31.4 ± 7.1 kg/m2. Every 1-h longer fasting duration was associated with increased total cholesterol (β = 5.79, P = 0.01), low-density lipoprotein (LDL) cholesterol (β = 4.47, P = 0.03), and LDL:high-density lipoprotein (HDL) ratio (β = 0.08, P = 0.04). For every 30-min later first mealtime, increases in total cholesterol, LDL cholesterol, and LDL:HDL ratios also were observed. Anti-inflammatory E-DII changes were associated with reduced total cholesterol and LDL cholesterol (among participants with shorter fasting durations, later last mealtime, or earlier first mealtime) and C-reactive protein (among earlier first mealtime and shorter fasting duration). Conclusions This study provides evidence for interaction between dietary timing and quality on cardiometabolic biomarkers. Worsening lipid profiles seen with longer fasting durations may be an artifact of skipped or delayed breakfast, underlining the potential importance of food consumption early in the morning.