Effect of nitrate supplementation on hepatic blood flow and glucose homeostasis: a double-blind, placebo-controlled, randomized control trial.

Study answer

What this study found

Nitrate-rich beetroot juice increased plasma nitrate and nitrite versus placebo, with older adults showing faster nitrite rise; increases persisted for 3 hours. Hepatic diffusion (ADC) and portal vein flux did not change with nitrate. Portal vein velocity decreased after nitrate in young adults but not in older adults. Plasma glucose, active/total GLP-1, and C-peptide were not reduced by nitrate; blood pressure did not differ. Authors conclude that acute dietary nitrate elevates circulating nitrite but does not modulate hepatic blood flow or glucose homeostasis in healthy young and older…

Study & population

Double-blind, placebo-controlled, crossover randomized trial; 37 participants enrolled (17 healthy young adults and 20 healthy older adults); 31 completed (16 young, 15 older); hepatic diffusion (ADC), portal vein flux and velocity measured by MRI; blood measures included plasma nitrate, nitrite, glucose, GLP-1 (total and active), and C-peptide at baseline…

Intervention

Beetroot juice beverage (140 mL) containing 11.91 mmol nitrate (nitrate-rich) or nitrate-depleted beetroot juice containing 0.01 mmol nitrate (placebo); consumed with a standardized breakfast; single acute dose per testing session; hourly MRI scans for 3 hours post-ingestion; 7-day washout between sessions.

Key limitation

Small sample size with limited power to detect small or age-specific effects; baseline differences in older adults for portal vein flux; short 3-hour observation window; MRI-based measures of hepatic diffusion/portal hemodynamics have variability; cross-over design potential carryover; findings in healthy individuals…

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Original abstract