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Dietary nitrate supplementation preserves peak oxygen uptake during Ramadan fasting in healthy adults

In a randomized controlled trial, healthy adults who consumed beetroot juice (providing ~6.45 mmol nitrate) twice daily for 10 days during Ramadan fasting maintained their absolute and relative peak oxygen uptake, while the control group experienced significant declines. Absolute VO2peak decreased by -155 mL/min in controls but increased by +67 mL/min in the nitrate group (P<0.01). Relative VO2peak changed by -2.4 mL/kg/min in controls versus +0.3 mL/kg/min in the nitrate group (P=0.02).

Last updated: Aug 23, 2026•1 RCTs•📖 Read as article →

Evidence Score

Evidence Score44/100
Human RCT★★☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Effects of dietary nitrate supplementation on peak oxygen uptake following 10 days of Ramadan fasting in healthy adults.

observational

Bhimani MM, Bommarito JC, Miners NI, Khangura PK, Stapleton RK, Sharma A, Thiessen JS, Cyr NO, McCarthy DG, Dong J, Cho CE, Millar PJ · Experimental physiology (2026)

Participants: N/A
Duration: 10 days
Intervention: 70 mL of beetroot juice (~6.45 mmol nitrate) twice daily for 10 days during Ramadan fasting
Outcome: Peak oxygen uptake (VO2peak) measured by indirect calorimetry during a maximal cycle ergometer ramp test; also body mass, blood pressure, urine specific gravity, sleep quality, physical activity, and peak power output
Effect Size: N/A (not reported in abstract)
Population: 21 healthy adults (13 females) observing Ramadan fasting

Result:

PubMed: 42613915DOI: 10.1113/EP093800

Mechanism Graph

Dietary nitrate is converted to nitrite and then nitric oxide in the body
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Nitric oxide enhances vasodilation and oxygen delivery to muscles
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Improved oxygen delivery may offset declines in aerobic capacity during fasting
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Result: VO2peak preserved in nitrate group versus decline in control

Limitations

  • ⚠Small sample size (n=21)
  • ⚠Self-reported physical activity; no objective monitoring
  • ⚠Short duration (10 days) may not reflect full Ramadan month
  • ⚠No blinding for control group (non-supplement control)

Frequently Asked Questions

What is the effect of beetroot juice on VO2peak during Ramadan fasting?▼

Beetroot juice supplementation (70 mL twice daily) prevented the decline in VO2peak observed in the control group after 10 days of Ramadan fasting.

How much nitrate is in the beetroot juice used in this study?▼

Each 70 mL serving contained approximately 6.45 mmol of nitrate, taken twice daily.

Did dietary nitrate affect body mass or blood pressure during Ramadan?▼

No significant differences were found between groups for changes in body mass, systolic or diastolic blood pressure, or urine specific gravity.

Is this study a randomized controlled trial?▼

Yes, it used a randomized design with 21 healthy participants assigned to either beetroot juice or a non-supplement control group.

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References

  1. 1.Bhimani MM, Bommarito JC, Miners NI, Khangura PK, Stapleton RK, Sharma A, Thiessen JS, Cyr NO, McCarthy DG, Dong J, Cho CE, Millar PJ. "Effects of dietary nitrate supplementation on peak oxygen uptake following 10 days of Ramadan fasting in healthy adults.." Experimental physiology, 2026. PMID: 42613915 DOI: 10.1113/EP093800
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.