What dose of dietary nitrate (in mmol or mg) is supported by trials to improve exercise performance?
Executive summary
Randomized trials and recent syntheses converge on an effective acute or short-term dietary nitrate dose of roughly 5–9 mmol per day (≈300–600 mg NO3−), taken about 2–3 hours before exercise, with multiple meta-analyses and reviews identifying this range as the most consistently ergogenic across studies [1] [2] [3]. Broader trial data show beneficial effects up to ~16.8 mmol (~1041 mg) in some protocols and report body-mass–adjusted dosing strategies, but heterogeneity across populations, exercise tasks, and study quality means the 5–9 mmol window is the best-supported practical recommendation to improve performance [1] [4] [5].
1. What the trials actually show about dose ranges
Narrative and systematic reviews summarize hundreds of trials and consistently report effective nitrate doses clustered around 5–9 mmol/day (≈300–600 mg NO3−), with some studies using as little as ~5 mmol and others using doses up to 16.8 mmol (~1041 mg) that also produced effects in selected settings [6] [1]. Meta-analyses that examined dose–response detected an inverse relationship for multi‑day protocols and estimated an optimal dose between 5 and 9.9 mmol·d−1 for protocols lasting ≥2 days [3], while other syntheses and sport‑science summaries endorse a similar effective range of ~5–7 mmol for observable physiological effects like reduced O2 cost and lower resting blood pressure [2] [5].
2. Timing, acute vs. chronic dosing, and body-mass approaches
Trials used both acute single-dose strategies (commonly 2–3 hours pre‑exercise) and short chronic loading (days to two weeks), with improvements reported from both approaches; the plasma nitrite time-course supports the 2–3 hour pre‑exercise window for acute benefit [1] [2]. Some investigators recommend body-mass–adjusted dosing (~0.1 mmol·kg−1, roughly 5–7 mmol for many adults) and report ergogenic effects with nitrate doses expressed per kg (or mg·kg−1), with studies noting effects at equivalent exposures of about 4.5 to 10.4 mg·kg−1 in intermittent high‑intensity tests [2] [7].
3. Who benefits most — training status and exercise type matter
The strongest and most reproducible benefits appear in less‑trained or recreational athletes and in exercise tasks of moderate duration or high intensity (notably ~10–17 minutes) where reductions in O2 cost or improvements in time‑trial performance translate to measurable gains [1] [4]. By contrast, results in highly trained elite cohorts and in some team‑sport field studies are mixed, and some trials report no performance benefit even at similar nitrate doses, underscoring heterogeneity by fitness, task, and study design [7] [8].
4. Limits of the evidence and safety caveats
Although multiple meta‑analyses support the 5–9 mmol/day window as optimal, the literature is heterogeneous: studies vary by nitrate source (beetroot juice vs. concentrated supplements), blinding, habitual diet control, and outcome measures, and several reviews note that trial quality and reporting limit firm dose‑response conclusions [4] [8]. Safety and long‑term effects of chronic high‑dose nitrate supplementation remain incompletely characterized in athletes, and supplement contamination is a practical concern for competitive athletes using commercial products [1].
5. Practical takeaway for performance dosing
Trials and consensus summaries indicate that an acute or short-term ingestion of about 5–9 mmol nitrate (~300–600 mg NO3−), taken ~2–3 hours before exercise, is the regimen most consistently associated with improved efficiency and performance; body-mass approaches (~0.1 mmol·kg−1) are an alternative for individualization, and longer loading protocols of similar daily doses can also be effective [2] [3] [6]. Given inter-study variability, athletes and coaches should weigh the evidence, monitor individual response, and consider dietary sources (eg, ~0.5 L beetroot juice can supply the effective dose) while being mindful of regulatory and safety issues documented in the literature [2] [9] [1].