Publication of Citrulline on Journal of the International Society of Sports Nutrition

KYOWA HAKKO BIO CO., LTD. (President and CEO: Chikakuni Kotani), published a research article titled ‘Oral L-citrulline^*1 supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study’ on Journal of the International Society of Sports Nutrition.

Summary
Many studies report that nitric oxide (NO) improves sport performance in human study. L-Citrulline is an amino acid present in the body and is a potent endogenous precursor of L-arginine, which is a substrate for NO synthase. Interestingly, it has been reported that oral supplementation of L-citrulline increases the plasma L-arginine level more effectively than L-arginine in healthy subjects. The aim of this study was to investigate the effect of oral supplementation of L-citrulline on cycling time trial performance in humans.
A randomized double-blind crossover study design was employed. Twenty-two well-trained males consumed 2.4 g/day of L-citrulline or placebo orally for 7 days, and took 2.4 g of L-citrulline or placebo 1 hour before a 4-km cycling time trial on Day 8. Time taken to complete the 4 km cycle, amino acid levels, and visual analog scale (VAS) scores was evaluated.
The results showed that L-citrulline supplementation significantly increased plasma L-arginine and reduced completion time by 1.5% (p < 0.05) compared to placebo. Moreover, L-citrulline significantly improved subjective feelings of muscle fatigue and concentration immediately after exercise.
We conclude that Oral L-citrulline supplementation reduced the time take to complete a cycle ergometer exercise trial.

Term
*1 L-Citrulline: Amino acid presents in the body and is a potent endogenous precursor of L-arginine, which is a substrate for NO synthase. L-Citrulline supplementation has been shown to exhibit various beneficial effects such as improving arterial stiffness, erectile function, and memory deficit through up-regulation of NO synthesis.

Reference
Journal of the International Society of Sports Nutrition. 13:6,2016.

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