Beetroot and Dietary Nitrates at Altitude: Can They Offset the Performance Hit of Thin Air?

When you ascend to altitude, your aerobic engine takes a hit. Reduced oxygen availability drives down VO2 max, raises the oxygen cost of exercise, and makes efforts that felt routine at sea level genuinely hard. Athletes have long looked for nutritional strategies to blunt this performance penalty — and beetroot juice at altitude has emerged as one of the most compelling candidates. The physiological rationale is sound, the research base is growing, and the practical application is simple. But whether dietary nitrates can meaningfully offset the hypoxic performance hit is a question that deserves a careful, evidence-based answer rather than supplement-marketing hype.

The Nitrate-Nitric Oxide Pathway

To understand why beetroot might matter at altitude, you first need to understand how dietary nitrate works in the body.

Inorganic nitrate (NO3⁻), abundant in beetroot, spinach, rocket, and celery, follows a pathway that bypasses the usual enzymatic route for nitric oxide (NO) production. Under normal conditions, the body synthesizes NO from the amino acid L-arginine via nitric oxide synthase (NOS) enzymes — a process that requires oxygen. At altitude, where tissue oxygenation is reduced, NOS-dependent NO production is compromised.

The nitrate pathway offers an alternative: NO3⁻ is absorbed in the gut, concentrated in saliva, reduced to nitrite (NO2⁻) by oral bacteria, and then further converted to NO in tissues — a process that is enhanced by low pH and low oxygen tension (hypoxia). In other words, the very conditions that impair the enzymatic NO pathway (hypoxia, acidosis during intense exercise) actually accelerate the dietary nitrate pathway. This is the mechanistic foundation for the hypothesis that nitrate supplementation should be particularly effective under altitude conditions.

What Nitric Oxide Does for Performance

NO is a signaling molecule with several performance-relevant effects:

Vasodilation: NO relaxes smooth muscle in blood vessel walls, increasing blood flow and oxygen delivery to working muscles
Reduced oxygen cost of exercise: Nitrate has been shown to reduce the phosphocreatine cost of ATP synthesis in skeletal muscle, improving mitochondrial efficiency — meaning less oxygen is needed per unit of work
Enhanced muscle fiber recruitment: Some evidence suggests NO improves the efficiency of calcium cycling in Type II muscle fibers
Mitigation of hypoxic pulmonary vasoconstriction: Critically for altitude, NO can partially offset the rise in pulmonary arterial pressure that occurs in hypoxia, improving pulmonary blood flow and arterial oxygen saturation (SpO2)

This last mechanism may be the most important for altitude performance specifically.

Key Research: What Do the Studies Show?

The Jonvik Study and Low-Oxygen Conditions

A landmark study by Masschelein et al. (2012, Journal of Applied Physiology) examined nitrate supplementation (0.1 mmol/kg/day inorganic nitrate for 3 days) in trained cyclists under moderate hypoxia (simulated 3,000 m). The nitrate group showed significantly improved time-to-exhaustion during hypoxic cycling compared to placebo, with attenuation of the hypoxia-induced performance decline. Importantly, blood nitrite levels in the nitrate condition were elevated at rest and during exercise, confirming successful conversion.

A follow-up by Kelly et al. (2014) in trained cyclists found that dietary nitrate supplementation reduced the VO2 cost of submaximal exercise during acute hypoxia — the same efficiency benefit seen at sea level, but potentially more impactful when oxygen is already scarce.

Pulmonary Vascular Effects

One of the most physiologically significant altitude-specific studies was conducted by Ramírez-Campillo et al. and complemented by work from Asahara and colleagues, examining NO and hypoxic pulmonary vasoconstriction (HPV). HPV is the lung's reflex response to low alveolar oxygen: pulmonary arterioles constrict, redirecting blood away from poorly ventilated lung segments. While adaptive in localized hypoxia (like a small pneumonia), HPV is largely counterproductive at high altitude, where the entire lung is hypoxic — it raises pulmonary artery pressure, increases right ventricular workload, and reduces SpO2.

Dietary nitrate has been shown to attenuate HPV, reducing pulmonary artery pressure in hypoxic conditions and improving oxygen saturation. Bailey et al. demonstrated in healthy volunteers that beetroot juice (490 mL, ~8 mmol NO3⁻) reduced the fall in SpO2 during hypoxic exercise compared to placebo. This is a direct performance and safety implication for altitude athletes: higher SpO2 during exercise means more oxygen delivered to the muscles and brain at a given workload.

VO2 Max at Altitude: Mixed Evidence

Where the evidence is less consistent is in improving absolute VO2 max at altitude. Several studies find that dietary nitrate reduces the oxygen cost of submaximal exercise (same work, less oxygen used) but does not fully restore the reduced VO2 max itself. The peak aerobic capacity remains lower than sea-level values, even with nitrate supplementation. This is expected — nitrate doesn't replace the missing hemoglobin-bound oxygen, it simply uses the available oxygen more efficiently.

For practical purposes, this means dietary nitrates are most valuable at moderate-to-high submaximal intensities (think: threshold, race pace, and long sustained efforts) rather than at absolute VO2 max ceiling work. The athlete who benefits most from altitude nitrate supplementation is one doing sustained aerobic or threshold training, not pure sprint or short VO2 max intervals.

Optimal Dosing at Altitude

How Much Nitrate?

Most of the positive studies in hypoxic conditions used doses equivalent to 5–9 mmol of inorganic nitrate. In practical terms:

70–140 mL of concentrated beetroot juice (typical "shots" contain ~5–6.4 mmol per 70 mL)
500 mL of raw beetroot juice (~7–8 mmol NO3⁻, depending on variety and soil nitrate content)
Whole beetroot: approximately 2–3 medium beets (300–400 g) provides a comparable dose but with more variability

The dose used in Masschelein et al. (6.2 mmol/day for 3 days) and Bailey et al. (~8 mmol single acute dose) represent the effective range. Some practitioners use 8–12 mmol for altitude-specific applications given the enhanced conversion efficiency in hypoxia.

Concentrated beet shots (e.g., 70 mL shots providing 6.4 mmol NO3⁻) are the most reliable delivery vehicle for training and competition due to controlled dose and minimal GI bulk.

Timing: Acute vs. Chronic Supplementation

Acute single dose: Peak plasma nitrite occurs approximately 2–3 hours after ingestion of a nitrate dose. For a single training session or competition, consume one to two concentrated beet shots 2–2.5 hours beforehand.

Chronic loading (3–7 days): Multiple studies suggest that chronic supplementation produces greater and more consistent effects than acute dosing alone. Tissue nitrite levels accumulate over several days, and oral bacterial colonies involved in conversion become established. A 3–6 day loading protocol before altitude arrival, continuing throughout the camp, is the recommended approach for altitude training blocks.

Key protocol for altitude camps:

Begin 3 days before altitude arrival
Continue throughout the block (daily dosing)
On training days: additional acute dose 2 hours pre-session
On rest or low-intensity days: single daily dose with a meal

Important: Do Not Use Antibacterial Mouthwash

The oral bacteria in the mouth are essential for the first reduction step (NO3⁻ → NO2⁻). Using antibacterial mouthwash — even a single use — abolishes the oral nitrate-reducing flora and can eliminate the nitrate benefit for 24–48 hours. Studies by Govoni et al. (2008) confirmed that mouthwash use completely blocked plasma nitrite elevation after dietary nitrate intake.

Athletes using nitrate supplementation should avoid antibacterial mouthwash entirely. Plain fluoride toothpaste without antibacterial agents is fine.

Altitude-Specific Considerations

Acclimatization Phase (Days 1–5)

The acute acclimatization phase — when EPO is rising, plasma volume is contracting, and the body is dealing with the full hypoxic load — is arguably when nitrate supplementation is most valuable. SpO2 is at its nadir, pulmonary vasoconstriction is highest, and any intervention that improves tissue oxygen delivery without adding metabolic cost is potentially beneficial.

Continue daily dosing through the first week. If altitude sickness symptoms develop, nitrate supplementation is not contraindicated but should be considered in the context of the overall management plan.

High-Intensity Training at Altitude

At altitude, athletes already struggle to reach sea-level intensities. Dietary nitrate's ability to reduce the oxygen cost of submaximal exercise means you can potentially sustain a higher absolute power or pace for a given physiological cost. In practical terms: if your altitude-adjusted threshold pace is 10% below sea level, nitrate supplementation may help you narrow that gap by 2–4% through improved mitochondrial efficiency and enhanced oxygen delivery.

This is not a cure for altitude's suppressive effect on performance — but it is a meaningful edge, and the evidence is substantially more convincing than for most nutritional supplements.

Interaction with Iron Supplementation

Athletes on altitude trips commonly supplement with iron to support erythropoiesis. Nitrate/nitrite can interact with iron-containing compounds in complex ways, but no clinically significant interactions have been identified in healthy athletes at normal supplementation doses. Iron and nitrate supplementation can be used concurrently without concern.

Practical Takeaways

1. Start 3 days before altitude arrival. Give the nitrate-nitrite-NO pathway time to establish before the hypoxic stress begins. This chronic loading phase produces more consistent results than relying on acute pre-workout doses alone.

2. Target 6–9 mmol of NO3⁻ per day. Two concentrated beetroot shots (70 mL each, ~6.4 mmol each) exceed this threshold. If using whole foods, track your intake from high-nitrate vegetables: beetroot, rocket, spinach, celery, and lettuce are the highest sources.

3. Abandon antibacterial mouthwash for the duration. This is non-negotiable. The oral bacterial pathway is the gateway to the entire nitrate benefit. Antibacterial agents eliminate it.

4. Time pre-training doses to 2–2.5 hours pre-session. Peak plasma nitrite arrives at approximately 2–3 hours post-ingestion. Don't consume your shot 30 minutes before exercise — the conversion won't be complete.

5. Expect GI adjustment in the first 1–2 days. High-nitrate foods can cause reddish urine and stools (beeturia — harmless), mild GI activity, and occasionally bloating. Starting with a lower dose (one shot, not two) for the first 2 days reduces initial GI disturbance.

6. Combine with a whole-foods dietary approach. Athletes whose diets are already rich in green leafy vegetables have naturally elevated plasma nitrite baselines. Supplemental nitrate from beet juice provides additional loading on top of this. If your altitude camp nutrition is already poor (high-stress travel, poor appetite typical in early altitude exposure), beet shots become even more important as a reliable delivery vehicle.

7. Manage expectations: nitrate supplements do not prevent altitude sickness. The ergogenic and SpO2-preserving effects are real but modest. Nitrate supplementation is not a substitute for proper acclimatization, hydration, pacing, or medical treatment of altitude-related illness. It is one tool in a comprehensive altitude performance strategy.

The Bottom Line on Dietary Nitrate Altitude Performance

The case for dietary nitrate altitude performance enhancement is among the strongest in the sports nutrition literature for any hypoxia-specific intervention. The mechanism is sound and directly addresses one of altitude's limiting factors: NO-dependent vasodilation and oxygen use efficiency are impaired in hypoxia, and the nitrate pathway is specifically enhanced by the same conditions. The evidence base spans multiple well-controlled studies showing improved time-to-exhaustion, reduced oxygen cost of exercise, attenuated SpO2 decline, and blunted hypoxic pulmonary vasoconstriction.

The intervention is low-cost, widely available, well-tolerated, and carries no significant safety concerns in healthy athletes.

For any athlete spending more than 3 days above 2,000 m — whether at a training camp, in a competition, or during a trekking expedition — a daily beet shot protocol starting 3 days before departure represents one of the highest return-on-investment nutritional strategies available. The thin air will still slow you down. But it will slow you down a little less.

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