Fast-food meal reduces peripheral artery endothelial function but not cerebral vascular hypercapnic reactivity in healthy young men

Consumption of a representative fast-food meal (FFMeal) acutely impairs peripheral conduit artery vascular function; however, the effect on cerebral vascular function remains unknown. This study tested the hypothesis that a FFMeal would impair cerebral vascular function as indexed by an attenuated increase in cerebral vascular conductance (CVCI) in the middle cerebral artery (MCA) during a hypercapnic challenge. Ten healthy men (age: 24 ± 3 years, BMI: 24.3 ± 3.8 kg/m² ) were studied under two conditions; a standardized FFMeal (990 kcals, 50% fat, 36% carbohydrate, 14% protein, and 2120 mg sodium) and a fasting control condition. Basal hemodynamics, cerebral vasomotor reactivity (CVMR), and brachial artery flow-mediated dilation (BA FMD) were completed after an overnight fast (Pre) and again 2 h and 4 h later both days. To assess CVMR, subjects rebreathed from a 5-L bag while MCA velocity (MCAV_mean ) was measured using transcranial Doppler (TCD) ultrasound and converted into CVCI (MCAV_mean /mean arterial pressure). Peripheral artery endothelial function was assessed via BA FMD following a standard 5-min occlusion protocol. As expected, BA FMD was reduced at 2 h (Pre: 6.6 ± 1.7% vs. 5.2 ± 1.8%, P = 0.01). However, despite significant impairment in BA FMD, neither peak CVCI_%baseline nor CVMR was affected by the FFMeal (Control-Pre: 1.9 ± 1.1, 2 h: 2.1 ± 1.1, 4 h: 1.7 ± 1.1 ∆CVCI%·∆P_ET CO₂^-1 vs. FFMeal-Pre: 2.1 ± 1.1, 2 h: 2.2 ± 0.7, 4 h: 1.9 ± 0.9 ∆CVCI%·∆P_ET CO₂^-1 , time × condition P = 0.88). These results suggest that cerebral vascular reactivity to hypercapnia in healthy young men is not altered by an acute FFMeal.