When to take Nitric oxide boosters (L-citrulline and beetroot)
Also known as beetroot juice, dietary nitrate, L-citrulline, citrulline malate
Take beetroot juice about 2 to 3 hours before exercise, and take L-citrulline about 1 to 2 hours before exercise. The time of day does not matter, but the time before your workout does.
Last reviewed October 13, 2026
Timing
| Best time | Any time of day |
|---|---|
| Food | With or without food |
| Fat-soluble | No |
- Beetroot juice: most studies gave it once, about 2.5 to 3 hours before exercise, or daily for up to 15 days.
- A review of 15 meta-analyses found beetroot taken 2 to 3 hours before exercise helped performance a little; daily use for 3 days or more added very little.
- Any benefit from beetroot may last up to 24 hours after you drink it.
- L-citrulline: in studies, single doses were taken 60 to 120 minutes before exercise. One weightlifting study used citrulline malate 1 hour before training.
Check with your doctor first if…
- Pink or red urine: beetroot can color your urine pink or red. This is harmless.
- Stomach upset: in one study, 6 of 41 people felt stomach discomfort after taking citrulline malate.
- Long-term use: the safety of citrulline taken for months has not been well studied, and beetroot has not been studied beyond several weeks.
- Beetroot powders: studies used juice or juice concentrate. It is not known whether beetroot powder capsules work the same way.
Amounts studied
Beetroot: most studies used about 500 mL (2 cups) of juice, giving about 310–682 mg (5–11 mmol) of nitrate. L-citrulline: endurance studies used 1.5–9 g, most often 6 g; one strength study used 8 g of citrulline malate (1 g citrulline malate holds about 566 mg citrulline).
Follow the serving size on your product’s label.
What the research says
| Area | Evidence | Summary |
|---|---|---|
| Exercise performance | Moderate | Reviews show beetroot juice gives small gains in endurance, mostly in regular exercisers rather than elite athletes. Effects were small and varied between studies.[2] |
| Endurance | Limited | A review of 9 trials found a single dose of L-citrulline did not improve endurance in young healthy adults. The evidence base is small.[3] |
| Muscle strength | Limited | In one study, weightlifters did more bench press repetitions after taking citrulline malate 1 hour before, but other studies disagree. NIH ODS calls the citrulline research limited and conflicting.[1] |
Questions
How long before a workout should I take beetroot?
Most studies used beetroot juice about 2 to 3 hours before exercise. Any benefit may last up to 24 hours.
When should I take L-citrulline before exercise?
Studies gave single doses 60 to 120 minutes before exercise. Research on citrulline is limited and mixed, so results are not certain.
Do nitric oxide boosters help with weightlifting?
There is little research on beetroot for weightlifting. One study found more bench press reps with citrulline malate, but the overall citrulline evidence is mixed.
Is red urine after beetroot normal?
Yes. Red pigments from beets can turn urine pink or red, and this is not a safety concern.
Can I take beetroot every day?
Studies found no safety concerns with about 2 cups of beetroot juice a day for several weeks. Longer use has not been studied.
Plan your whole routine
Add Nitric oxide boosters (L-citrulline and beetroot) and everything else you take to the planner to see your morning, midday and evening, and what to keep apart.
Open the plannerSources
- Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals, NIH ODS (accessed October 13, 2026)
- Effects of Beetroot Juice on Physical Performance in Professional Athletes and Healthy Individuals: An Umbrella Review (Nutrients, 2025), PMC (accessed October 13, 2026)
- Effects of citrulline on endurance performance in young healthy adults: a systematic review and meta-analysis (J Int Soc Sports Nutr, 2023), PMC (accessed October 13, 2026)
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. It is general information, not medical advice: talk with your doctor or pharmacist before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a health condition.