Abstract
Caloric restriction (CR) and dietary nitrate supplementation are nutritional interventions with pleiotropic physiological functions. This pilot study investigates the combined effects of CR and nitrate-rich beetroot juice (BRJ) on metabolic, vascular, and cognitive functions in overweight and obese middle-aged and older adults. This was a two-arm, parallel randomized clinical trial including 29 participants allocated to CR + BRJ (
= 15) or CR alone (
= 14) for 14 days. Body composition, resting energy expenditure (REE), and hand-grip strength were measured. Resting blood pressure (BP) and microvascular endothelial function were measured, and Trail-Making Test A and B were used to assess cognitive function. Salivary nitrate and nitrite, and urinary nitrate and 8-isoprostane concentrations were measured. Changes in body composition, REE, and systolic and diastolic BP were similar between the two interventions (
> 0.05). The CR + BRJ intervention produced greater changes in average microvascular flux (
= 0.03), NO-dependent endothelial activity (
= 0.02), and TMT-B cognitive scores (
= 0.012) compared to CR alone. Changes in urinary 8-isoprostane were greater in the CR + BRJ group (
= 0.02), and they were inversely associated with changes in average microvascular flux (r = -0.53,
= 0.003). These preliminary findings suggest that greater effects on vascular and cognitive functions could be achieved by combining CR with dietary nitrate supplementation.