title: Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction.
abstract: OBJECTIVE
  To test the efficacy and safety of oral L-citrulline supplementation in improving erection hardness in patients with mild erectile dysfunction (ED). L-arginine supplementation improves nitric oxide-mediated vasodilation and endothelial function; however, oral administration has been hampered by extensive presystemic metabolism. In contrast, L-citrulline escapes presystemic metabolism and is converted to L-arginine, thus setting the rationale for oral L-citrulline supplementation as a donor for the L-arginine/nitric oxide pathway of penile erection.
  
  
  METHODS
  In the present single-blind study, men with mild ED (erection hardness score of 3) received a placebo for 1 month and L-citrulline, 1.5 g/d, for another month. The erection hardness score, number of intercourses per month, treatment satisfaction, and adverse events were recorded.
  
  
  RESULTS
  A total of 24 patients, mean age 56.5 ± 9.8 years, were entered and concluded the study without adverse events. The improvement in the erection hardness score from 3 (mild ED) to 4 (normal erectile function) occurred in 2 (8.3%) of the 24 men when taking placebo and 12 (50%) of the 24 men when taking L-citrulline (P < .01). The mean number of intercourses per month increased from 1.37 ± 0.93 at baseline to 1.53 ± 1.00 at the end of the placebo phase (P = .57) and 2.3 ± 1.37 at the end of the treatment phase (P < .01). All patients reporting an erection hardness score improvement from 3 to 4 reported being very satisfied.
  
  
  CONCLUSIONS
  Although less effective than phosphodiesterase type-5 enzyme inhibitors, at least in the short term, L-citrulline supplementation has been proved to be safe and psychologically well accepted by patients. Its role as an alternative treatment for mild to moderate ED, particularly in patients with a psychologically fear of phosphodiesterase type-5 enzyme inhibitors, deserves further research.
authors.affiliation: Department of Urology and Renal Transplantation, University of Foggia, Foggia, Italy. luigicormio@libero.it
authors.forename: Luigi
authors.initials: L
authors.lastname: Cormio
authors.forename: Mario
authors.initials: M
authors.lastname: De Siati
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Lorusso
authors.forename: Oscar
authors.initials: O
authors.lastname: Selvaggio
authors.forename: Lucia
authors.initials: L
authors.lastname: Mirabella
authors.forename: Francesca
authors.initials: F
authors.lastname: Sanguedolce
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Carrieri
mesh_terms: D000284:Administration, Oral; D002956:Citrulline / Q000008:administration & dosage*; D019587:Dietary Supplements; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D010410:Penile Erection / Q000187:drug effects*; D010865:Pilot Projects; D011446:Prospective Studies; D012720:Severity of Illness Index; D016037:Single-Blind Method
chemical_list: D002956:Citrulline