How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Beetroot juice (nitrates)
A dietary source of nitrates, converted into nitric oxide by the body. One of the few endurance aids that holds up against trials.
Benefits
- Reduces oxygen consumption at equal effort: the same pace costs less, and time to exhaustion increases
- Lowers blood pressure by 3 to 4.4 mmHg on average (meta-analyses of 16 and 22 trials)
- Increases power during repeated sprints with little recovery (24 sprints of 6 seconds)
- Improves endurance at high altitude, and by 24% the exercise capacity of heart failure patients
Precautions
Colors urine and stool red: impressive, harmless. Antiseptic mouthwashes cancel the effect, as nitrate conversion starts with the bacteria in the mouth. Also good to know: the benefit diminishes as fitness levels rise — in elite 1,500 m runners and well-trained cyclists over a one-hour effort, several trials found no improvement.
Recommended dosage
Around 8 mmol of nitrates, or 140 ml of concentrated juice, about 2 hours before exercise.
How to take it
- Dose: around 8 mmol of nitrates, or 140 ml of concentrated juice in several trials. Beyond 8.4 mmol, exercise tolerance no longer improved.
- When: 2 hours before effort in the rowing trial, where the high dose (8.4 mmol) performed better than the moderate dose (4.2 mmol).
- Single dose or several days: a single dose has sometimes been enough, for example for cycling at altitude, but several positive trials give the juice for 5 to 7 days in a row.
- Not for everyone: in elite 1,500 m runners, and in well-trained cyclists on a one-hour time trial, no gain.
- Not with caffeine: the combination added nothing to caffeine alone, and could even reduce its benefits.
- For blood pressure: about −4 mmHg on systolic, with a more pronounced effect for higher doses and longer intakes. In already treated hypertensive patients, one week changed nothing.
What the studies say
This systematic review and meta-analysis of 22 randomized clinical trials examined the effects of beetroot juice supplementation on blood pressure. Overall, beetroot juice significantly reduced systolic blood pressure (by -3.55 mmHg) and diastolic blood pressure (by -1.32 mmHg). The blood-pressure-lowering effect was more pronounced with longer study durations and higher doses of beetroot juice. The study also highlights potential nitrate-independent effects to explain these reductions in blood pressure.
Bahadoran Z, Mirmiran P, Kabir A, Azizi F, Ghasemi A. — Advances in nutrition (Bethesda, Md.) (2017) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more