Pine bark

Pine Bark Extract

1. Identity, Botanical Classification, and Commercial Forms

The pine (Pinus L.) is a genus of more than 100 different species which grow widespread in Europe and the Mediterranean basin, Asia, and Northern America. Extracts can be sourced from different Pinus species such as P. densiflora, P. maritima, P. massonia, P. nigra, P. pinaster, P. radiata, or P. sylvestris.

Pycnogenol® is the registered name of a standardized extract of the bark of the French maritime pine, Pinus pinaster Aiton, subspecies Atlantica des Villar, containing mainly phenolic acids and procyanidins. The extract's active ingredients include proanthocyanidins, shown to have photoprotective, antimicrobial, antioxidant, anti-inflammatory, and anticarcinogenic effects. Its anti-inflammatory properties may include the inhibition of IFN-γ and down-regulation of expression of interstitial factors. Pycnogenol is an extract of French maritime pine bark (Pinus pinaster), which grows only on the southwest coast of France in Les Landes de Gascogne.

Proanthocyanidins are among the most abundant constituents in pine bark extracts (PBEs), including Pycnogenol® from the bark of the European coastal or French maritime pine Pinus pinaster, Enzogenol® from the bark of New Zealand pine Pinus radiata (Monterey or Insignis pine), and PMBE from the bark of China pine Pinus massoniana.

Pycnogenol® is a standardized bark extract of the French maritime pine Pinus pinaster, Aiton, subspecies Atlantica des Villar. The quality of this extract is specified in the United States Pharmacopeia (USP 28).

Pycnogenol is currently used to describe the particular mixture of procyanidins extracted from pine tree bark in France (Pinus pinaster). The consistent extract product is a fine, reddish-brown powder that is water-soluble.

Commercial Preparations and Forms

Commercial pine bark extracts are typically sold as capsules or tablets, though powders and liquid tinctures are available. The majority of pine bark extracts sold as herbal supplements today come from maritime pines. Maritime pine bark extract is made by first grinding pine bark, then washing and soaking it in hot water. Next, the solids are removed from the liquid extract. The liquid extract can then be used as is or further processed by freeze-drying and grinding it into a powder.

Most research on French maritime pine extract has used Pycnogenol, as opposed to the other standardized extracts, oligopin and flavangenol. These extracts have slightly different chemical compositions, due to different extraction techniques, and there currently isn't enough evidence to know whether oligopin and flavangenol work the same as pycnogenol.

2. Traditional and Historical Use

The medicinal use of pine bark from different pine species can be traced back to Hippocrates, 400 B.C., and was applied in many parts of the world. Traditionally, pine bark has been used for its anti-inflammatory and wound healing effects.

Botanical extracts from pine bark have a long-standing history of use in traditional medicine, for example, for wound healing.

A well-documented historical account concerns the French explorer Jacques Cartier. There is a written account of an event that happened in 1534, when a French ship led by explorer Jacques Cartier became stranded in ice near Quebec, Canada. Cartier's crew became severely sick from scurvy, a fatal disease caused by a lack of vitamin C in the diet. Cartier's crew was saved when a Quebec Indian instructed them to drink a brew made from pine bark and needles.

In the 1940s, scientist Jacques Masquelier began studying the health effects of pine bark after learning that indigenous peoples of North America were using pine bark tea to heal scurvy and wounds.

Pine bark has been used for centuries generally for its anti-oxidant and anti-inflammatory activity and its vitamin C content.

Traditional use also extended to Asia. Its use in Chinese remedies dates back thousands of years. Traditional Chinese cultures used the needles, bark, and turpentine of the Pinus massoniana tree to make folk remedies that promoted constriction and hemostasis to prevent and stop bleeding. They also used pine bark to detoxify, ease joint stiffness, and support healthy blood pressure.

3. Key Constituents and Active Compounds

Pine bark extracts are concentrated sources of phenolic compounds such as procyanidins, flavonoids, and phenolic acids.

Between 65–75% of Pycnogenol® by weight are procyanidins comprising catechin and epicatechin subunits with varying chain lengths. Other constituents are polyphenolic monomers, phenolic or cinnamic acids, and their glycosides.

The consistent extract of pycnogenol is composed of phenolic components from monomers (taxifolin, epicatechin, and catechin), condensed flavonoids (grouped as procyanidins and proanthocyanidins), and phenolic acids (cinnamic acids and some glycosides).

A number of phenolic acids that are derivatives of benzoic acid, vanillic acid, gallic acid, or cinnamic acid derivatives exist both free and in combination with glucose. The major procyanidin dimers include B1, consisting of catechin and epicatechin, and B3, consisting of two catechin monomers, and lower concentrations of the equivalent dimers.

Bioavailability and Pharmacokinetics

Based on plasma concentration profiles it can be concluded that low molecular weight constituents of the extract, such as catechin, caffeic and ferulic acid, and taxifolin are readily absorbed from the small intestine into systemic circulation. Procyanidin oligomers and polymers are subjected to gut microbial degradation in the large intestine, yielding small bioavailable metabolites such as 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone.

After intake of Pycnogenol®, constituents and metabolites have been detected in blood cells, synovial fluid, and saliva, indicating a substantial distribution in compartments other than serum. In studies simultaneously investigating concentrations in different specimens, a preferential distribution of individual compounds has been observed — for example, of ferulic acid and 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone into synovial fluid compared to serum. The main route of elimination of constituents and metabolites of the French pine bark extract is renal excretion.

Pine bark extract is a potent antioxidant and acts as a free radical scavenger by reacting with both hydroxyl radicals and singlet oxygen. It enhances the synthesis of antioxidant enzymes and regenerates vitamins C and E.

4. Established Mechanisms of Action

As investigated in several in vitro, in vivo, and clinical studies, Pycnogenol® French maritime pine bark extract showed antioxidative effects, anti-inflammatory abilities, beneficial effects on endothelial function, and reinforcing effects on the extracellular matrix.

Anti-inflammatory Action

Pycnogenol can reduce inflammation by acting as a blocker of inflammatory transcription factors NF-κB and lowering the levels of MMP-9.

Pycnogenol treatment was dose-dependently associated with significantly less release of nitric oxide (NO), TNF-α, IL-6, and IL-1β, and lower levels of intercellular adhesion molecule 1 (ICAM-1) and perilipin 2 (PLIN2). Furthermore, this effect was replicated in primary brain microglia.

Blood samples from seven healthy volunteers were obtained before and after five days' administration of 200 mg Pycnogenol per day. Plasma samples statistically significantly inhibited matrix metalloproteinase 9 (MMP-9) release from human monocytes and NF-κB activation. This provides evidence that bioavailable active principles of Pycnogenol exert anti-inflammatory effects by inhibition of proinflammatory gene expression, consistent with documented clinical observations.

Pycnogenol's anti-oxidative and anti-inflammatory efficacy extends to suppressing lipid peroxidation, total reactive species (RS), superoxide (O₂), nitric oxide (NO), peroxynitrite (ONOO⁻), pro-inflammatory inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and nuclear factor-kappa B (NF-κB) nuclear translocation.

Endothelial Function and Nitric Oxide Modulation

Pycnogenol antagonizes the vasoconstriction caused by epinephrine and norepinephrine by increasing the activity of endothelial nitric oxide synthase. Dilation of the small blood vessels has been observed in patients with cardiovascular disease, whereas in smokers, Pycnogenol prevents smoking-induced platelet aggregation and reduces the concentration of thromboxane. The ability to inhibit angiotensin-converting enzyme is associated with a mild antihypertensive effect.

Extracellular Matrix Reinforcement

Pycnogenol is a highly potent antioxidant with a high affinity for collagen. Furthermore, Pycnogenol® exerts some of its beneficial effects as it optimizes blood flow by improving endothelial function. Since blood vessels run through all tissues, the effects of Pycnogenol® were investigated in cardiovascular and venous health, as well as skin, hair, and eye health.

5. Scientific Evidence by Area of Use

The overall body of clinical research on pine bark extract is substantial but carries significant limitations. Currently, available evidence is insufficient to support the efficacy of pine bark extracts and the certainty of evidence across all outcomes is very low, partly due to small sample sizes (11–156 participants), inconsistent outcome measures, and poor-quality reporting across the trials. Clinical research on pine bark extracts has methodological limitations and currently there is no conclusive evidence of efficacy in treating any specific health condition. Large, robust, long-term studies using pine bark extracts that meet accepted standards for pharmaceutical quality are required.

Despite this caveat, a substantial body of RCT-based data has accumulated, particularly for the proprietary Pycnogenol® extract. In 39 randomized double-blind, placebo-controlled (RDP) human clinical trials including 2,009 subjects, Pycnogenol® French maritime pine bark extract supplementation for two weeks to six months has been shown to beneficially affect cardiovascular health, chronic venous insufficiency, cognition, joint health, skin health, eye health, women's health, respiratory health and allergies, oral health, and sports performance. The important caveat noted by Weichmann and Rohdewald (2024) is that the results from studies using Pycnogenol® cannot be extrapolated to other plant or pine bark extracts.

5.1 Cardiovascular Health and Blood Pressure

A range of cardiovascular effects has been reported for pycnogenol, including vasorelaxant effects, ability to inhibit angiotensin-converting enzyme (ACE), and increase in the microcirculation by increasing capillary resistance.

A meta-analysis of blood pressure trials found quantifiable effects. A total of 12 clinical trials involving 922 participants were included in the meta-analysis. Pooled analysis suggested that pycnogenol supplementation can reduce systolic blood pressure (SBP) by −3.22 mmHg (95% CI [−5.52, −0.92]) and diastolic blood pressure (DBP) by −1.91 mmHg (95% CI [−3.64, −0.18]). These effects are statistically significant but modest in absolute magnitude.

In a specific clinical trial, a placebo-controlled, double-blind, parallel group study was performed with 58 patients to investigate effects of French maritime pine bark extract (Pycnogenol) on patients with hypertension. Supplementation with 100 mg Pycnogenol over a period of 12 weeks helped to reduce the dose of the calcium antagonist nifedipine in a statistically significant manner. The intake of Pycnogenol decreased endothelin-1 concentrations significantly compared to placebo while concentrations of 6-keto prostaglandin F1α in plasma were significantly higher compared to placebo.

In respect to cardiovascular symptoms, the extract has an antihypertensive effect, slows down the progression of atherosclerosis, and prevents venous thrombosis, as shown in double-blind, placebo-controlled clinical studies.

5.2 Chronic Venous Insufficiency

Two randomized, double-blind, placebo-controlled studies on chronic venous insufficiency have shown an interesting clinical application of Pycnogenol® that can be mechanistically explained by its beneficial effects on endothelial function and its anti-inflammatory action.

At 100 mg, Pycnogenol produces significant effects on edema and signs of CVI. Pycnogenol is very effective in acute venous edema with a selective action on lower limb swelling and edema. Pycnogenol has improved venous tone in clinical studies and improves healing of venous ulcers.

A registry study in diabetic patients with CVI found that after 8 weeks, the differences between Pycnogenol® and elastic compression were statistically significant for skin resting flux (RF), rate of ankle swelling (RAS), transcutaneous PO₂ and PCO₂, indicating a significant improvement in microcirculatory perfusion with Pycnogenol® in comparison with elastic compression. Clinical symptoms assessed by the Composite Symptom Score (CSS), the Venous Clinical Severity Score (VCSS), and the Venous Disability Score (VDS) were significantly lower in the Pycnogenol® group than in the compression group.

Pycnogenol may reduce symptoms of chronic venous insufficiency and osteoarthritis thanks to its antioxidant, anti-inflammatory, and vasoactive properties; however, the evidence is relatively weak.

5.3 Cognition and Neurological Health

Pine bark is used in traditional medicine to treat conditions most frequently associated with improving cognition.

Among 79 adults with Parkinson's disease and mild cognitive impairment treated with pine bark extract [Pycnogenol: 150 mg] or placebo once daily for 8 weeks, symptoms of tremor, bradykinesia, and cognitive impairments were improved with treatment, and "no side effects of supplementation were observed." This finding requires confirmation in larger trials.

One of the mechanisms behind Pycnogenol's ability to suppress neuroinflammation is its ability to inhibit the NF-κB and AP-1 pathway, which suppresses the activation of microglia. In addition, Pycnogenol modulates nitric oxide (NO) production through the suppression of inducible nitric oxide synthase (iNOS), a key enzyme of NO.

5.4 Attention-Deficit/Hyperactivity Disorder (ADHD)

In a small RCT involving 61 children, Pycnogenol improved attention and visual-motor coordination and reduced hyperactivity compared with placebo.

However, the evidence at the systematic review level is rated as very uncertain. In children with ADHD, it is not known whether pine bark extract decreases inattention and hyperactivity assessed by parent- and teacher-rating scales (narrative synthesis; one study; 57 participants; very low-certainty evidence) or increases the change in visual-motoric coordination and concentration (MD 3.37, 95% CI 2.41 to 4.33; one study; 57 participants; very low-certainty evidence).

5.5 Diabetes and Blood Glucose

As reported in studies in China and the US, type 2 diabetes as well as diabetic retinopathy is improved with Pycnogenol. The extract restores mobility of seniors in patients suffering from osteoarthritis, and Pycnogenol reduces pain and stiffness.

However, a 2025 umbrella review concluded that evidence supports the use of ginger and turmeric for glycemic control, and reported that the pine bark extract Pycnogenol had minimal effects on HbA1c and fasting blood glucose levels, with no reported serious adverse events.

5.6 Diabetic Retinopathy and Eye Health

Owing to its effects on microcirculation, inflammation, and oxidation, Pycnogenol® was found to have positive effects on eye health. The retina is the tissue with the highest metabolic rate in the body and is particularly susceptible to oxidative stress. The eye tissue is particularly exposed to UV light, which generates reactive oxygen species in cells. Furthermore, metabolic conditions like diabetes involve a pathological oxidative stress, which can lead to diabetic retinopathy. Pycnogenol® showed effects to stop further progression of retinopathy and ameliorate the eyesight of diabetics by stabilizing and sealing leaky capillaries of the retina, stopping further outflow of blood.

All studies on retinopathy unequivocally showed that Pycnogenol retains progression of retinopathy and partly recovers visual acuity. Treatment efficacy of Pycnogenol was at least as good as that of calcium dobesilate. Pycnogenol was shown to improve capillary resistance and reduce leakages into the retina. These findings, while consistent, derive from small trials and warrant confirmation in larger studies.

5.7 Joint Health and Osteoarthritis

There is mixed evidence about the effectiveness of pycnogenol for osteoarthritis. Pycnogenol might reduce overall symptoms, but it does not seem to reduce pain or improve the ability to perform daily tasks.

In patients suffering from osteoarthritis, Pycnogenol reduces pain and stiffness and use of analgesics. The mechanistic rationale rests on NF-κB inhibition and reduced MMP-9 activity, both of which are relevant to cartilage degradation pathways.

5.8 Skin Health

Pycnogenol binds with skin proteins collagen and elastin to help support skin elasticity and structure. In research, those taking Pycnogenol supplements daily over 12 weeks experienced significantly increased collagen (type 1) production by 41%. This in turn can contribute to reduction of wrinkles and fine lines.

Pycnogenol supplementation also improves production of hyaluronic acid, the compound responsible for skin hydration, with one study showing a boost of up to 44% after 12 weeks. This benefit was particularly noticeable in the skin of subjects who had dry skin prior to the study.

5.9 Women's Health

Pycnogenol relieves premenstrual symptoms, including abdominal pain, and this action may be associated with the spasmolytic action of some phenolic acids.

Early research shows that taking pycnogenol by mouth decreases menopausal symptoms, including tiredness, headache, depression and anxiety, and hot flashes. These findings are preliminary and based on small trials.

5.10 Respiratory Health and Asthma

In adults with asthma, the Cochrane review found that it is not known whether pine bark extract increases change in FEV1 % predicted (MD 7.70, 95% CI 3.19 to 12.21; one study; 44 participants; very low-certainty evidence).

5.11 Erectile and Sexual Dysfunction

The Cochrane review included three studies on erectile dysfunction involving 277 participants. Many of these used pine bark extract in combination with L-arginine, making it difficult to attribute effects to pine bark alone. Evidence strength is rated as very low certainty.

5.12 Traumatic Brain Injury

In individuals with traumatic brain injury, it is not known whether pine bark extract decreases cognitive failure scores (MD −2.24, 95% CI −11.17 to 6.69; one study; 56 participants; very low-certainty evidence) or post-concussion symptoms (MD −0.76, 95% CI −5.39 to 3.87; one study; 56 participants; very low-certainty evidence).

Overall Evidence Assessment

A Cochrane review of the efficacy of pine bark extracts for treating various chronic disorders identified 27 randomized controlled trials (1,641 patients) in 10 different chronic disorders and concluded that "no definitive conclusions regarding the efficacy or safety of pine bark supplements are possible."

The overall risk of bias was low for four studies, high for one, and unclear for 22 studies. This refers to the extent to which the methods used in a study enable it to determine the truth. The certainty of evidence was very low for all outcomes across all chronic diseases in the included studies.

6. Dosages Reported in Clinical Studies

A commonly used commercial preparation available in Europe (Pycnogenol®) is a standardized extract of Pinus pinaster with 70% procyanidins that is used in doses of 100 to 200 mg daily.

Many clinical trials are methodologically weak, making it difficult to support the use of pine bark extract for any condition. In clinical trials, Pycnogenol dosages ranged from 20 to 360 mg (or were weight-based), with the most common duration of use being 2 to 3 weeks; however, longer-term use has been described.

Condition-specific dosages as reported in clinical trials include the following:

• ADHD: 1 mg/kg/day
• Asthma: 100 mg/day
• Chronic venous insufficiency: 150 to 360 mg/day
• Diabetes: 50 to 200 mg/day
• Dyslipidemia: 120 to 150 mg/day
• Dysmenorrhea: 30 to 60 mg/day
• Endometriosis: 60 mg/day
• Erectile dysfunction: 120 mg/day
• Hypertension: 100 to 200 mg/day
• Osteoarthritis: 100 to 150 mg/day
• Retinopathy: 20 to 160 mg/day

The included studies tested different treatment durations (4 weeks to 6 months), doses, and dosages, as well as single-ingredient (Pycnogenol®, Flavangenol®, Oligopin®, Enzogenol®) and multi-ingredient products with different chemical profiles.

7. Safety Considerations and Interactions

General Tolerability

Pine bark is generally recognized as safe and has not been linked to serum enzyme elevations during therapy nor to episodes of clinically apparent liver injury.

Pycnogenol is well tolerated with some reports of dizziness, drowsiness, rash, and stomach complaints. Pycnogenol may be safe during the third trimester of pregnancy, but safety has not been established during lactation.

Tolerance was generally very good and side effects were rare, mostly referring to gastric discomfort.

Pregnancy and Special Populations

Information regarding safety and efficacy during pregnancy and lactation is lacking. Pine bark extract at a dose of 30 mg/day has been studied in a small clinical trial for pain in the third trimester of pregnancy and did not result in any adverse effects; however, this should not be regarded as evidence of safety in pregnancy.

Potential Interactions

Some medications for blood clotting, diabetes, and immunosuppressants may interact with pine bark.

People with autoimmune conditions, bleeding disorders, or those scheduled for surgery should use caution or avoid Pycnogenol, as it may increase immune activity or bleeding risk.

Rare Adverse Events

A case report of rhabdomyolysis associated with excess pycnogenol (maritime pine bark extract) was published in 2025 in the journal Cureus. This represents an isolated adverse event report and its causality has not been definitively established.

Liver Safety

While there have been many clinical trials of pine bark for these indications, all have been limited in size and duration of therapy. Pine bark has not been linked to serum enzyme elevations during therapy nor to episodes of clinically apparent liver injury.

Evidence Gaps in Safety Data

For most comparisons, studies did not report outcomes of hospital admissions or serious adverse events. Small sample sizes, limited numbers of RCTs per condition, variation in outcome measures, and poor reporting of the included RCTs mean no definitive conclusions regarding the efficacy or safety of pine bark extract supplements are possible.

References

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