Clinical assessment of a supplement of Pycnogenol® and L-arginine in Japanese patients with mild to moderate erectile dysfunction

Phytother Res. 2012 Feb;26(2):204-7. doi: 10.1002/ptr.3462. Epub 2011 May 27.


A double-blind parallel group comparison design clinical study was conducted in Japanese patients with mild to moderate erectile dysfunction to investigate the efficacy of a supplement containing Pycnogenol® and L-arginine. Subjects were instructed to take a supplement (Pycnogenol® 60 mg/day, L-arginine 690 mg/day and aspartic acid 552 mg/day) or an identical placebo for 8 weeks, and the results were assessed using the five-item erectile domain (IIEF-5) of the International Index of Erectile Function. Additionally, blood biochemistry, urinalysis and salivary testosterone were measured. Eight weeks of supplement intake improved the total score of the IIEF-5. In particular, a marked improvement was observed in 'hardness of erection' and 'satisfaction with sexual intercourse'. A decrease in blood pressure, aspartate transaminase and γ-glutamyl transpeptidase (γ-GTP), and a slight increase in salivary testosterone were observed in the supplement group. No adverse reactions were observed during the study period. In conclusion, Pycnogenol® in combination with L-arginine as a dietary supplement is effective and safe in Japanese patients with mild to moderate erectile dysfunction.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Arginine / therapeutic use*
  • Asian People
  • Aspartate Aminotransferases / metabolism
  • Blood Pressure
  • Double-Blind Method
  • Erectile Dysfunction / drug therapy*
  • Flavonoids / therapeutic use*
  • Humans
  • Male
  • Middle Aged
  • Patient Satisfaction
  • Penile Erection
  • Plant Extracts
  • Testosterone / analysis
  • gamma-Glutamyltransferase / metabolism


  • Flavonoids
  • Plant Extracts
  • Testosterone
  • pycnogenols
  • Arginine
  • gamma-Glutamyltransferase
  • Aspartate Aminotransferases