Beetroot and Nitrate Supplements: The Athlete's Complete Guide

In a supplement landscape characterized by overpromising and underdelivering, dietary nitrate — sourced primarily from beetroot — stands out as a genuine ergogenic aid with a mechanistic basis and replicated evidence. Since the landmark research from the University of Exeter in 2009, beetroot and nitrate supplementation has moved from an obscure curiosity to a broadly used performance tool in endurance sports.

This guide explains the mechanism accurately, specifies what the research shows (and what it does not), provides a clear dosing protocol, and covers the mouthwash interaction that eliminates the supplement's effectiveness if ignored.

The mechanism: nitrate to nitrite to nitric oxide

The ergogenic effect of dietary nitrate operates through a distinct pathway from the arginine-to-nitric-oxide route that most "NO booster" supplements target.

The nitrate-nitrite-nitric oxide pathway:

1. Dietary nitrate (NO3-) is absorbed in the small intestine and enters systemic circulation
2. The blood transports nitrate to the salivary glands, which concentrate it and secrete it into saliva — concentrations in saliva can be 10–20 times higher than in plasma
3. Anaerobic bacteria in the oral cavity (particularly on the tongue's surface) reduce nitrate to nitrite (NO2-) — this bacterial reduction step is essential and irreplaceable
4. Swallowed nitrite reaches the stomach, where it can be reduced further to nitric oxide by stomach acid and certain enzymes
5. Nitrite absorbed into the bloodstream is converted to nitric oxide in tissues, particularly under the low-oxygen, low-pH conditions present in working muscles during intense exercise

The key distinction from arginine-based NO supplements: this pathway does not depend on endothelial nitric oxide synthase (eNOS) and is actually more efficient under hypoxic conditions — exactly the conditions during intense exercise when you most need NO production. The arginine-eNOS pathway becomes less efficient as oxygen drops. The nitrate-nitrite-NO pathway becomes more efficient.

What nitric oxide does in the working muscle:

• Vasodilation: relaxes smooth muscle in blood vessel walls, increasing blood flow and oxygen delivery
• Reduces the ATP cost of muscular contraction — effectively making muscle more efficient per unit of oxygen consumed
• May enhance calcium release in muscle fibers, improving contractile performance
• Reduces the oxygen cost of phosphocreatine resynthesis between high-intensity efforts

The evidence: what beetroot/nitrate actually improves

The research on dietary nitrate is extensive and unusually consistent. Key findings:

Oxygen efficiency: The most replicated finding is a 3–5% reduction in the oxygen cost of submaximal exercise. This means an athlete consuming dietary nitrate can sustain the same pace or power output using less oxygen — effectively improving exercise economy. The Larsen et al. (2007) study was early and influential; Bailey et al. (2009) demonstrated a 16% improvement in time to exhaustion at high intensity in a well-controlled crossover design.

Time trial performance: Multiple well-designed randomized crossover trials show improvements in cycling and running time trial performance of 1–3% with nitrate supplementation. In competition, these are substantial margins.

Oxygen uptake at VO2 max: Some studies show improved power at VO2 max, not just at submaximal intensities.

Team sport performance: Research in team sport athletes (football, rugby) has shown improvements in repeated sprint performance and high-intensity running volume during simulated match protocols.

Where the evidence is weaker: Benefits are most consistent in recreational to well-trained athletes (VO2 max approximately 50–65 mL/kg/min). Highly elite athletes (national and international competitors, VO2 max >65) show smaller and less consistent improvements, potentially because they have already optimized NO production through training adaptations. Strength training performance is not a primary target for nitrate supplementation.

Dosing: how much and when

The effective dose is 300–600mg of dietary nitrate, which corresponds to:

• Approximately 300–500ml (10–17oz) of concentrated beetroot juice
• 2–3 shots of standard commercial beetroot shots (like Beet-It Sport — each 70ml shot typically contains approximately 400mg nitrate)
• Standardized nitrate supplements (potassium nitrate or sodium nitrate capsules) with dosage verified on the label

Timing is important:

• Nitrate must be converted to nitrite by oral bacteria, nitrite absorbed, and NO generated — this process takes 2–3 hours from ingestion
• Most research uses a timing of 2.5 hours before exercise for single acute doses
• Do not take beetroot supplements immediately before training expecting benefit — the conversion pipeline requires time

Chronic vs. acute supplementation:

• Acute (single pre-exercise dose) does produce performance benefits
• Chronic supplementation (3–6 days of daily dosing before a key event) may produce greater plasma nitrite elevation and enhanced performance effects
• For key competitions, combining 3–5 days of daily nitrate loading with a final dose 2.5 hours before the event is a evidence-consistent approach

The mouthwash interaction: the most important caveat in nitrate research

This is the detail that separates athletes who actually benefit from beetroot supplementation from those who consume it and wonder why it is not working.

The conversion of nitrate to nitrite — step 3 in the pathway described above — is performed entirely by oral bacteria. These bacteria live on the surface of the tongue and in the crypts of oral tissue. They are not a digestive enzyme your body produces. They are symbiotic oral bacteria.

Antibacterial mouthwash — particularly chlorhexidine-based products — destroys these bacteria. Studies have demonstrated that using chlorhexidine mouthwash eliminates the salivary nitrate-to-nitrite conversion for 12–24 hours, which fully blocks the nitrate-to-NO pathway and abolishes the ergogenic effect of beetroot supplementation.

Research by Lansley et al. and subsequently Govoni et al. confirmed this in exercise contexts: subjects using mouthwash before or after consuming nitrate showed no reduction in oxygen cost of exercise and no performance improvement compared to placebo.

Practical implications:

• Avoid chlorhexidine mouthwash when using beetroot/nitrate supplements — including the 12–24 hours before consuming nitrate
• Standard fluoride toothpaste does not significantly disrupt oral bacteria in the same way, but minimize brushing intensity immediately before consuming nitrate supplements
• Alcohol-based mouthwashes may partially disrupt the oral microbiome — caution is reasonable
• Antibiotics that reduce oral bacteria (a common side effect of broad-spectrum antibiotic treatment) may temporarily reduce nitrate-to-nitrite conversion efficiency

The beetroot side effects you should know about

Beeturia: Beetroot contains betalain pigments that are not fully broken down by everyone. Approximately 10–14% of the population (and more following high beetroot intake) will notice pink or red urine and possibly pink stool after consuming significant amounts of beetroot. This is completely harmless but can be alarming if you are not expecting it. If you see red urine after a training session, recall whether you consumed beetroot before assuming something is wrong.

GI tolerance: High doses of beetroot juice (>500ml) can cause digestive discomfort in some individuals. Starting with a lower dose and increasing gradually over days is sensible for sensitive individuals. Concentrated shots are easier on the stomach than large volumes of juice.

Blood pressure: Nitrate supplementation reliably lowers blood pressure, typically by 2–5 mmHg systolic. For athletes with normal blood pressure, this is unlikely to be clinically significant. Athletes with already-low blood pressure or those on blood pressure medications should be aware of additive effects.

Interaction with PDE5 inhibitors: Do not combine beetroot/nitrate supplements with erectile dysfunction medications (sildenafil, tadalafil, etc.) — both lower blood pressure via the NO-cGMP pathway, and the combination can produce dangerous hypotension.

How beetroot compares to arginine-based NO boosters

Many pre-workout supplements claim to boost nitric oxide through arginine or its precursors. As described in detail in the citrulline guide, oral arginine has poor bioavailability due to first-pass metabolism by arginase in the gut and liver. L-citrulline is a more effective arginine-based approach.

Dietary nitrate and the arginine/citrulline pathway are complementary, not redundant — they generate NO through different mechanisms and have different exercise-intensity profiles. Nitrate's pathway is particularly efficient under hypoxic conditions (during intense exercise), while the arginine-eNOS pathway is more active under normoxic conditions.

Using both dietary nitrate and citrulline together is not well-studied as a combined protocol, but there is no known interaction that would make it unsafe.

Who should use beetroot/nitrate supplements

The strongest candidates for beetroot supplementation:

• Endurance athletes (cyclists, runners, rowers, triathletes) competing at sub-maximal intensities where oxygen efficiency is performance-limiting
• Team sport athletes doing repeated high-intensity efforts
• Well-trained recreational athletes (VO2 max 45–65) who want a legal, evidence-based performance edge

Less likely to benefit significantly:

• Elite/professional athletes with very high baseline VO2 max
• Pure strength or power athletes (the mechanism is most relevant to oxygen-dependent exercise)
• Athletes who regularly use antibacterial mouthwash (the benefit is blocked)

The bottom line

Dietary nitrate from beetroot or standardized nitrate supplements is one of the most evidence-backed ergogenic aids available to athletes. The mechanism — nitrate reduction to nitrite by oral bacteria, then to nitric oxide in working muscle — is well-understood, and the performance effects (improved exercise efficiency, 1–3% improvement in time trial performance) are replicated across dozens of independent studies.

Dose at 300–600mg nitrate, 2–3 hours before exercise. Use chronic loading (3–5 days) before key events. Never use chlorhexidine mouthwash around beetroot supplementation — it blocks the entire mechanism. Expect red urine and do not be alarmed.

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