Chronobiology of meal timing in early-stage hypertension: a controlled feeding pilot study investigating the effects on renal and vascular function

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. Ten young adults with elevated blood pressure or stage 1 hypertension (means ± SD: 26 ± 8 yr, 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-h urine collection and simultaneous 24-h ambulatory blood pressure monitoring. Daytime fractional excretion of sodium was greater after MMC compared with EMC (MMC vs. EMC: 0.84 ± 0.28 vs. 0.35 ± 0.13%, <i>P</i> = 0.008). However, nighttime sodium excretion was not elevated after EMC (0.48 ± 0.24 vs. 0.39 ± 0.30%, <i>P</i> = 0.314), suggestive of overnight sodium retention. There were increased systolic (126 ± 6 vs. 121 ± 6 mmHg, <i>P</i> = 0.028), diastolic (80 ± 4 vs. 77 ± 6.4 mmHg, <i>P</i> = 0.028), and mean arterial (95 ± 5 vs. 91 ± 6 mmHg, <i>P</i> = 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%, <i>P</i> = 0.249). Resting systolic blood pressure was increased the morning following EMC (119 ± 8 vs.121.8 ± 9 mmHg, <i>P</i> = 0.018). 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 control was uncoupled from renal-mediated mechanisms.<b>NEW & NOTEWORTHY</b> Using a controlled feeding intervention, we investigated the time-of-day impact of Western-style meal consumption on acute blood pressure and renal responses in young adults with early-stage hypertension. Our pilot results translate preclinical work demonstrating that endogenous diurnal kidney function does not acutely respond to food as a time cue. Therefore, timing of a high sodium meal that was misaligned with the endogenous kidney function rhythm extended sodium retention, and blood pressure regulation was potentially uncoupled from renal-mediated mechanisms.