Chronobiology of Meal Timing in Early-Stage Hypertension: A Controlled Feeding Pilot Study Investigating the Effects on Renal and Vascular Function

Introduction: Lifestyle intervention is critical for young adults with early-stage hypertension. A Western-diet has negative effects on kidney function and blood pressure; however, time-of-day effects are understudied. We hypothesized that consumption of a Western-style meal that is misaligned with the endogenous circadian rhythm would have adverse effects on blood pressure, kidney function and vascular function. Methods: Ten young adults with elevated blood pressure or stage-1 hypertension (Mean±SD; 26±8years, 50% female) underwent a randomized crossover, isocaloric controlled feeding intervention. Participants were allocated to receive a Western-style meal high in sodium, sugar and saturated fat in the morning (MMC) or the evening (EMC). Participants completed 24-hour urine collection and simultaneous 24-hour ambulatory blood pressure monitoring. Results: Daytime fractional excretion of sodium was greater after MMC compared to EMC ( MMC vs. EMC: 0.84±0.28 vs. 0.35±0.13%, p=0.008). However, nighttime sodium excretion was not elevated after EMC (0.48±0.24 vs. 0.39±0.30%, p=0.314), suggestive of overnight sodium retention. There were increased systolic (126±6 vs. 121±6mmHg, p=0.028), diastolic (80±4 vs. 77±6.4mmHg, p=0.028), and mean arterial (95±5 vs. 91±6mmHg, p=0.028) blood pressures during waking hours of MMC. Following consumption of the EMC, nocturnal blood pressure elevation was mitigated, presumably through protective sodium storage mechanisms ( systolic pressure dipping: 15±5 vs. 12±5%, p=0.249). Resting systolic blood pressure was increased the morning following EMC (119±8 vs.121.8±9mmHg, p=0.018). Conclusions: The findings suggest that in young adults with early-stage hypertension a misaligned Western-style meal consumed late at night results in extended sodium retention and nocturnal blood pressure was uncoupled from renal mediated mechanisms.