Even though older people with high blood pressure are already taking medicine for it, their bodies can still turn nitrates from food (like beets or spinach) into useful compounds — but this doesn’t seem to lower their blood pressure or improve their blood vessels over time.

In older adults (≥65 years) with treated hypertension (stable on antihypertensive meds for ≥3 months), a single acute dose of dietary nitrate (e.g., 6.4 mmol sodium nitrate in beetroot juice) would be compared to placebo (nitrate-free juice) in a crossover design. Plasma and salivary nitrate/nitrite would be measured at baseline, 1h, 2h, 4h, and 6h post-intake; vascular function (flow-mediated dilation) and ambulatory blood pressure would be monitored over 24h. The study would test whether nitrate intake reliably elevates nitrate/nitrite without sustained BP or vascular improvement.

In older adults (≥65 years) with treated hypertension, participants would be randomized to daily dietary nitrate (e.g., 500 mL beetroot juice providing ~6.4 mmol nitrate) or placebo for 8 weeks. Plasma and salivary nitrate/nitrite would be measured weekly; vascular function (brachial FMD, arterial stiffness) and 24-hour ambulatory BP would be assessed at baseline, 4 weeks, and 8 weeks. The study would determine if nitrate metabolism remains active over time despite lack of sustained BP or vascular benefit.

In older adults with treated hypertension, participants would receive a single oral dose of 15N-labeled sodium nitrate. Plasma, saliva, and urine would be sampled over 24h to track the conversion of labeled nitrate → nitrite → nitric oxide metabolites. Vascular reactivity and BP would be measured concurrently. This would directly confirm the metabolic pathway is active (via isotope tracing) even when no hemodynamic changes occur.

A cohort of older adults with treated hypertension would be placed on a controlled diet for 7 days, with standardized dietary nitrate intake (e.g., 300 mg/day from spinach/beetroot) and no other nitrate sources. Plasma and salivary nitrate/nitrite would be measured daily; BP and vascular function tracked. This would assess whether nitrate metabolism persists under real-world dietary conditions without confounding supplements.

Among older adults with treated hypertension given a single nitrate-rich meal, individuals with robust plasma/salivary nitrate/nitrite increases (top quartile) would be compared to those with minimal increases (bottom quartile). Both groups would be assessed for vascular function and BP changes. This would test whether pathway functionality (biomarker rise) is dissociated from hemodynamic outcomes.