Synopsis

Source of validity: Scientific
Rating (out of 5): 2

L-citrulline is a non-essential amino acid that serves as a precursor to L-arginine, a substrate for nitric oxide (NO) synthesis. NO is a key mediator of vasodilation and plays a critical role in penile erection. The rationale for using L-citrulline in erectile dysfunction (ED) is based on its ability to enhance NO production, thereby improving blood flow to the penis. Several small-scale clinical studies have investigated this effect. For example, a 2011 pilot study (Urology, 2011) involving men with mild ED found that L-citrulline supplementation (1.5 g daily for one month) led to an improvement in erection hardness and satisfaction compared to placebo. Other studies have suggested similar modest benefits, especially among men with mild to moderate ED.

However, the evidence base remains limited. Most studies to date are small and of short duration, and the improvements reported are generally less pronounced than those seen with standard treatments like PDE5 inhibitors (e.g., sildenafil). Systematic reviews conclude that while L-citrulline may offer a safe, well-tolerated alternative or adjunct for some men, robust, high-quality clinical trials are lacking. There is no strong traditional use of L-citrulline for ED; its use is primarily based on the scientific understanding of NO pathways. Therefore, while some scientific evidence supports its use, it is not strong, and the ingredient should not be considered a first-line therapy for ED.

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