Evidence supporting the use of: L-citrulline
For the health condition: Exercise

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Synopsis

Source of validity: Scientific
Rating (out of 5): 3

L-citrulline is a non-essential amino acid commonly used as a dietary supplement to support exercise performance and recovery. Scientific evidence suggests that L-citrulline supplementation can enhance exercise capacity, primarily by increasing nitric oxide (NO) production. This occurs because citrulline is a precursor to arginine, which in turn is a substrate for NO synthesis. Increased NO levels can promote vasodilation, improving blood flow, oxygen delivery, and nutrient transport to muscles during physical activity.

Several randomized controlled trials have examined the effects of L-citrulline on exercise performance. Studies indicate that acute and chronic supplementation (typically 6–8 grams of L-citrulline malate) can reduce muscle soreness after intense exercise, delay the onset of muscle fatigue, and improve exercise performance in activities such as weightlifting and cycling. For example, a 2010 study published in the Journal of Strength and Conditioning Research found that subjects who took L-citrulline malate before resistance exercise performed more repetitions and reported less muscle soreness compared to placebo.

However, while results are promising, some studies report only modest benefits, and not all findings are consistent. The magnitude of effect may depend on the type of exercise, dosage, and population studied. Overall, the evidence base is moderate, supporting the use of L-citrulline for exercise enhancement but indicating that effects may vary between individuals.

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