Abstract
BACKGROUND: Circulating cortisol concentrations are connected to diet and the neurological systems that regulate food intake. Skipping breakfast can diminish the typical drop in circulating cortisol concentrations. OBJECTIVES: Determine 1) whether overnight fasted males and females differ in salivary cortisol (CORT) dynamics after consuming a high-fat test meal, 2) if these differences in postprandial (PP) CORT explain variation in cardiovascular status later in the day, and 3) whether PP CORT mediates sex-based differences in cardiovascular status. METHODS: This cross-sectional study examined >300 male and female participants. The recruitment sampling scheme consisted of sex (male and female) × age (18‒33 y, 34‒49 y, 50‒65 y) × BMI (normal weight: 18.5‒24.99, overweight: 25‒29.99, and obese: 30‒39.99). The study test visit was conducted at the USDA Western Human Nutrition Research Center and included a high-fat test meal, an emotion-induction (anger recall) task, and collection of blood, saliva, self-reported mood, and physiological information under fasted, PP, and post anger-recall conditions. RESULTS: After an overnight fast and following the test meal, PP CORT descended significantly (P (time × sex) = 0.00008) more sharply in females compared with males. Fasting CORT did not differ (P = 0.620) between males and females, but females displayed lower CORT at 30 min (P < 0.007), 60 min (P < 0.005), and 90 min (P < 0.010) following the test meal. Higher PP CORT associated with elevated anger-induced heart rate (β: 0.050 ± 0.022; P = 0.0232), elevated anger-induced sympathetic tone (β: 0.232 ± 0.105; P = 0.0282), and lower endothelial function (β: ‒0.1637 ± 0.0698; P = 0.0197). Endothelial function, and anger-induced heart rate and sympathetic tone differed between males and females, with variation in PP CORT partially explaining these sex-based differences. CONCLUSIONS: The magnitude of CORT decline after consuming the first daily meal may contribute to sex-based differences in downstream cardiovascular reactivity.