The Rate of Cortisol Decline After Consuming a High-Fat Test Meal for Breakfast Partially Explained Sex-Dependent Variation in Post Ingestive Cardiovascular Status

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.