The Claim
In trained cyclists, oral supplementation with citrulline at a dosage of 3g twice daily for 28 days has no statistically significant effect on plasma nitric oxide metabolite concentrations compared to placebo.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
In trained cyclists, taking 3 grams of citrulline twice daily for 28 days does not raise levels of nitric oxide metabolites in the blood compared to a placebo.
See the scientific wording
In trained cyclists, supplementation with citrulline (3g twice daily) for 28 days does not significantly increase plasma nitric oxide metabolites compared to placebo, contradicting the hypothesis that citrulline enhances NO production in this population.
Citrulline turns into arginine in the kidneys, and arginine is used by blood vessel cells to make nitric oxide. But in trained cyclists, the enzyme that makes nitric oxide is already working at full capacity from regular training, so extra arginine does not make more nitric oxide. At the same time, exercise produces free radicals that destroy nitric oxide before it can be measured, so even if some extra nitric oxide is made, it disappears quickly.
What the research says
1 studyThe study gave cyclists citrulline pills for a month and found their nitric oxide levels didn’t go up any more than in people who took sugar pills — so the supplement didn’t work as expected.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.