Two studies have shown that therapy with the combination of L-arginine and Pine Bark Extract is significantly more successful in improving erectile dysfunction than supplementation with L-arginine alone.

L-arginine alone: inconclusive results

L-arginine is the body’s only available raw material for producing the molecule NO, nitric oxide. NO is involved in vascular toning; specifically, it signals the tissue of the interior wall of blood vessels, the endothelium, to dilate. It also plays an important role in the contraction and relaxation of muscle.

While it was hoped that pure L-arginine would be a natural, simple and well-tolerated sexual potency enhancer. These expectations did not quite materialize. Studies conducted in this research area showed only moderate effects, particularly when doses consisted of 3,000 mg a day or less.

A dose of 5,000 mg L-arginine per day attained the best results.1

Arginine and Pine Bark Extract

First Study 2003

However, supplementation with the combination of L-arginine and Pine Bark Extract proved to be very convincing. This combination therapy was studied as early as 2003 by Stanislavov and his colleagues.2 In the study, men with mild to moderate erectile dysfunction received the following therapy regimen: at the start, only 1,700 mg L-arginine; after four weeks, L-arginine with 40 mg of Pine Bark Extract; and after another four weeks, L-arginine with 80 mg of Pine Bark Extract.

The result: taking l-arginine alone (1,700 mg a day) did not show measurable improvement. But once Pine Bark Extract was added to the supplementation with L-arginine, the majority of men reported significantly less sexual potency problems.

Studies from 2008 confirm the results

The first study garnered approval, but also criticism from the scientific community due to the way it was structured. The study failed to compare the results of the men receiving the combination therapy with results of a control group that would have received a placebo.

Therefore, in 2008, the same group of authors again researched the effects of combination therapy with L-arginine and Pine Bark Extract on erectile dysfunction.3 The study was designed according to the highest possible clinical standards. Double-blind, placebo-controlled, and randomized studies are considered the “gold standard” in clinical trials and their results are deemed valid and reliable.

The result of this study: more than 90% of the men receiving the combination supplementation reported improvement in their sex life. Virtually none of the study participants receiving the placebo reported improvement.

In a subsequent, similar study, the effects of 2,800 mg L-arginine in combination with 80 mg of Pine Bark Extract per day were measured on a group of 124 patients over a period of six months.4 The results of the previous study were confirmed: the combination of arginine and Pine Bark Extract can improve erectile dysfunction.

% Positive effect confirmed



  1. Chen et al.;”Effect of oral administration of high-dose nitric oxide donor L-arginine in men with organic erectile dysfunction: results of a double-blind, randomized, placebo-controlled study.”; BJU Int. 1999 Feb;83(3):269-73.;
  2. Stanislavov R1, Nikolova V. “Treatment of erectile dysfunction with pycnogenol and L-arginine.” J Sex Marital Ther. 2003 May-Jun;29(3):207-13.
  3. Stanislavov R1, Nikolova V, Rohdewald P.; “Improvement of erectile function with Prelox: a randomized, double-blind, placebo-controlled, crossover trial.”; Int J Impot Res. 2008 Mar-Apr;20(2):173-80. Epub 2007 Aug 16.
  4. Ledda A1, Belcaro G, Cesarone MR, Dugall M, Schönlau F.; “Investigation of a complex plant extract for mild to moderate erectile dysfunction in a randomized, double-blind, placebo-controlled, parallel-arm study.”;BJU Int. 2010 Oct;106(7):1030-3. doi: 10.1111/j.1464-410X.2010.09213.x. Epub 2010 Feb 22.,
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