Supplement
Red spinach extract is a nitrate-rich plant extract that the body can turn into nitric oxide, a molecule that helps blood vessels widen. People mostly look at it for aerobic exercise performance, and the evidence is limited: in small crossover trials, people finished a 4-km cycling time trial faster than on placebo. Only 42 people took part across those studies, so the findings are early.
Sources: PMID 31136549; PMID 29910440
- Updated
- How we grade
- 4 studies cited
- Best evidence
- Grade C
- Conditions studied
- 3
- Outcomes
- 5
- Graded outcomes
- 0032
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Aerobic Exercise Performance In a double-blind crossover RCT (n=17), 7 days of 1g red spinach extract improved 4-km cycling time trial completion time, average power, and speed vs placebo. A separate crossover trial (n=14) found RSE significantly increased VO2 at ventilatory threshold (+6.1%). A 15-day supplementation study (n=11) found ~19% greater time-to-exhaustion during high-intensity exercise with RSE vs placebo. | Improves (the measure goes up) | Small effect | 2 studies | 42 people | ||
Studies that measured aerobic exercise performance | ||||||
General
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Nitric Oxide Production Multiple crossover RCTs consistently demonstrate that red spinach extract dramatically increases plasma nitrate levels (+255% at 65-75 min post-ingestion in one study, +447% in another). A 15-day trial (n=11) found significantly elevated exhaled nitric oxide (41 vs 21 ppb) following RSE vs placebo. | Improves (the measure goes up) | Large effect | 2 studies | 40 people | ||
| Blood Pressure In a crossover RCT (n=17), red spinach extract supplementation significantly reduced post-exercise diastolic blood pressure vs placebo. A 15-day supplementation trial (n=11) found RSE significantly lowered systolic blood pressure (124 vs 128 mmHg). However, an acute single-dose crossover study (n=15) found no significant changes in resting blood pressure. | Improves (the measure goes down) | Small effect | 1 study | 28 people | ||
Studies that measured blood pressure | ||||||
Cardiovascular Health
- Vascular Function: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Vascular Function A randomized double-blind crossover study (n=15) found acute red spinach extract ingestion increased reactive hyperemia calf blood flow by 13.7% vs a 14.0% decrease with placebo. However, no differential response was observed in brachial artery flow-mediated dilation. | Improves (the measure goes up) | Small effect | 1 study | 15 people | ||
Studies that measured vascular function | ||||||
Anaerobic Exercise Performance
- Anaerobic Exercise Performance: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Anaerobic Exercise Performance In a crossover study of NCAA female soccer athletes (n=11), acute red spinach extract did not improve peak or mean power during repeated Wingate tests, but significantly reduced fatigue index. A 7-day trial in resistance-trained males (n=10) found no significant improvement in bench press repetitions, peak power, or mean power with RSE supplementation. | Improves (the measure goes up) | Small effect | 1 study | 21 people | ||
Studies that measured anaerobic exercise performance | ||||||
Key findings
- Aerobic Exercise PerformanceImproves (the measure goes up)
- Nitric Oxide ProductionImproves (the measure goes up)
- Blood PressureImproves (the measure goes down)
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- Grade C
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Studies cited
4 studies from PubMed
- Red Spinach Extract Supplementation Improves Cycle Time Trial Performance in Recreationally Active Men and Women
- Impact of Red Spinach Extract Supplementation on Bench Press Performance, Muscle Oxygenation, and Cognitive Function in Resistance-Trained Males
- Red Spinach Extract Increases Ventilatory Threshold during Graded Exercise Testing
- Differential vascular reactivity responses acutely following ingestion of a nitrate rich red spinach extract