Vascular effects of dietary nitrate supplementation in older adults with coronary artery disease: A randomized, placebo-controlled, crossover pilot trial.

Coronary artery disease (CAD) is characterized by endothelial dysfunction, arterial stiffening, and abnormal central hemodynamics, which are independent predictors of adverse cardiovascular events. Dietary nitrate supplementation using beetroot-derived products is a promising strategy, but its vascular effects in adults with CAD remain unclear. This randomized, double-blind, placebo-controlled, crossover pilot trial evaluated the safety, feasibility, and vascular effects of dietary nitrate supplementation to inform the development of a full-scale trial. Eight older adults with confirmed CAD (6 males and 2 females; age 74 [8] years; body mass index 29.2 [5.0] kg·m-2; mean [SD]) were randomized to twice-daily, 2-week supplementation with either nitrate-rich beetroot juice (NRBJ) or nitrate-depleted beetroot juice (NDBJ; placebo). We found that the intervention was well-tolerated, resulting in 100% participant retention, 100% intervention adherence, and no adverse effects requiring medical treatment. Compared to pre-intervention values, brachial artery flow-mediated dilation, expressed as %Δ, improved by 0.98% following NRBJ (90% CI: 0.17 to 1.80), corresponding to a medium-to-large effect size (Hedges' g: 0.72), whereas values remained unchanged following NDBJ (Mean Δ: -0.75%, 90% CI: -1.53 to 0.04). Between-arm comparisons revealed that NRBJ yielded a 1.73% greater improvement in flow-mediated dilation than NDBJ (90% CI: 0.32 to 3.15), representing a medium-to-large effect size (Hedges' g: 0.73). NRBJ resulted in negligible changes in arterial stiffness and hemodynamics. Collectively, these results suggest that dietary nitrate supplementation is highly feasible and well tolerated, and that NRBJ generates promising endothelial effects in older adults with CAD. These findings justify a subsequent, fully powered randomized controlled trial.