Benefits
Blood pressure studies: mixed, very low certainty
A meta-analysis of 7 double-blind Pycnogenol trials found no significant change in blood pressure. A 2025 analysis of 27 trials of pine bark extracts found drops of about 2 mmHg but rated that evidence very low certainty, found signs of publication bias, and saw no drop at 200 mg a day. A 130-person Stanford trial of a Japanese-made pine bark extract (Flavangenol) found no effect versus placebo. One small Swiss Pycnogenol trial found better blood vessel widening without lower blood pressure.
Heavy legs: small, mostly open studies
Small trials, mostly from one research group and mostly unblinded, reported less leg swelling and heaviness in people with chronic venous insufficiency. Two small trials from 2000 were positive but tiny, and European venous guidelines do not include pine bark extract.
Memory: limited evidence
One double-blind trial in 101 adults aged 60 to 85 found better working memory after 3 months of 150 mg a day of Pycnogenol, and a small trial of Enzogenol with vitamin C found faster spatial working memory. A planned 12-month Pycnogenol trial has not published its main results, and most other memory studies are open registry studies from one research group.
Attention scores in children
In small trials in children with ADHD, Pycnogenol was reported to improve some attention and behavior ratings. In the largest trial (88 children), teachers saw improvement but parents did not, and it could not show Pycnogenol was as good as methylphenidate. A small adult trial found no effect. It is not a replacement for medical care.
Breathing studies (small trials)
Two small trials, one in 60 children funded by Horphag, reported better breathing measures and less rescue-inhaler use with Pycnogenol alongside usual care. A Cochrane review rated this evidence very low certainty. It is not a replacement for prescribed treatment.
Skin hydration and elasticity
A double-blind crossover trial in 76 outdoor workers found that 100 mg a day of Pycnogenol for 12 weeks prevented the usual autumn drop in skin hydration. Claims of protection from sunburn rest on one uncontrolled study in 21 people.
Antioxidant in lab tests
Procyanidins are antioxidants in laboratory tests. In people, a few trials found lower oxidative stress markers, such as 15-F2t-isoprostane in a small Swiss heart trial. The FTC called a seller's claim that pycnogenol was 20 times more protective than vitamin C unsubstantiated in 2000.
CRP marker: results vary by trial
A meta-analysis of 5 trials (324 adults) of Pycnogenol, a branded French maritime pine bark extract, found lower CRP overall, but heterogeneity was very high (I² 99%), two trials were not randomized, and the two double-blind trials at 200 mg/day showed no clear change, so the true effect is uncertain. In a subgroup analysis by the Belcaro group of a 3-month knee osteoarthritis trial (100 mg/day), among people with high CRP, it fell from 3.9 to 1.1 mg/L vs 3.9 to 3.6 on placebo.
Mechanism of action
Blood vessel lining effects
In small trials, Pycnogenol improved flow-mediated dilation and lowered endothelin-1, a vessel-narrowing signal. These effects on the vessel lining are the proposed basis for its circulation claims.
Antioxidant and anti-inflammatory activity
Procyanidins are antioxidants in laboratory tests. In people, results on inflammation markers are mixed.
Absorption and metabolites
The large procyanidin chains are poorly absorbed. After a dose, small phenolic compounds and a gut-bacteria metabolite (M1) appear in the blood at low levels that vary widely between people.
Capillary effects (lab and animal data)
Laboratory and animal studies suggest procyanidins may reduce capillary leakiness. Human venous studies were mostly small and open.
Clinical trials
Double-blind, randomized, placebo-controlled crossover: 200 mg a day for 8 weeks on top of standard therapy. Supported by an unrestricted Horphag grant. (Enseleit et al. 2012, Eur Heart J)
23 adults with stable coronary artery disease.
Flow-mediated dilation improved (treatment effect 2.75 percentage points) and an oxidative stress marker fell slightly, but blood pressure, inflammation markers and platelet adhesion did not change.
Randomized, placebo-controlled trial: 200 mg a day of Flavangenol (Toyo-FVG), not Pycnogenol, for 12 weeks; funded by the extract's maker per ClinicalTrials.gov. (Drieling et al. 2010, Arch Intern Med)
130 adults at increased cardiovascular risk.
No difference from placebo in blood pressure, cholesterol, glucose, insulin or CRP.
Randomized, double-blind, placebo-controlled trial: 1 mg per kg a day for 4 weeks; Horphag-funded. (Trebatická et al. 2006, Eur Child Adolesc Psychiatry)
61 children with ADHD.
Hyperactivity fell and attention ratings improved on Pycnogenol, with symptoms returning a month after stopping. A Cochrane review rated this evidence very low certainty.
Double-blind, placebo-controlled trial: 100 mg three times a day for 2 months. (Arcangeli 2000, Fitoterapia)
40 adults with chronic venous insufficiency.
Swelling, heaviness and pain fell on Pycnogenol, with no effect on placebo. A small, early trial; most later venous studies were open studies from one research group.