Pine

Pine (Pinus spp.) as a Dietary Supplement and Medicinal Ingredient

1. Identity: Botanical Classification, Natural Source, and Commercial Forms

1.1 Botanical Identity

Among conifers, the pine (Pinus L.) is a genus of more than 100 different species which grow widespread in Europe and the Mediterranean basin, Asia, and in Northern America. In the context of dietary supplements and medicinal use, the term "pine" most often refers to the bark, needles, resin, seeds, or essential oil derived from one or more species of this genus. The most extensively studied and commercially significant species in the supplement market is Pinus pinaster Aiton (syn. Pinus maritima), known as the French maritime pine; however, other species — including Pinus radiata (Monterey pine), Pinus densiflora (Japanese red pine), Pinus sylvestris (Scots pine), Pinus strobus (Eastern white pine), and Pinus nigra (black pine) — also serve as sources of commercially available bark extracts and needle preparations.

The sources of pine bark (Pinus spp.) extract come from various species and countries including Pinus pinaster from France, Pinus radiata from the USA, and Pinus densiflora from Korea. Pine seeds, needles, cones, and bark contain different categories of phytochemicals which are essential for plant growth and development as well as having protective functions for the pines.

1.2 Botanical Parts Used

All major anatomical parts of pine trees have recorded medicinal or nutritional uses:

• Bark (particularly the outer bark): The primary source of commercially standardized polyphenol-rich extracts.
• Needles (leaves): Used historically as infusions (teas), tinctures, essential oils, and poultices. There are over one hundred species of pine worldwide, and most have recorded medicinal uses. Cultures around the globe have used the needles, inner bark, and resin for similar ailments — internally, pine is a traditional remedy for coughs, colds, allergies, and urinary tract and sinus infections.
• Resin and turpentine: Used topically and as a source of essential oil components.
• Seeds (pine nuts): Consumed as food.
• Essential oil (distilled from needles and twigs): Used in aromatherapy and topical preparations.

1.3 Major Commercial Preparations and Brand Names

Pine bark extracts are marketed under various brand names including Pycnogenol®, ProVens®, PineXol®, Flavangenol®, Prelox®, Lady Prelox®, Enzogenol®, and Oligopin®. Of these, Pycnogenol® is by far the most researched proprietary extract. There are many pine bark extracts on the market from different pine tree species, from different countries, and with different levels of efficacy for human health. Pycnogenol® French maritime pine bark extract (Horphag Research) is the most researched pine bark extract, with over 450 published studies and over 160 human clinical trials including over 12,000 subjects.

Pycnogenol® is French maritime pine bark extract of the outer bark of Pinus pinaster Ait. subsp. atlantica. Its specifications are described in the USP 28 — Dietary Supplements. The French maritime pine bark extract Pycnogenol® is produced from the outer protective bark of the French Pinus pinaster Aiton, subspecies atlantica, which is particularly resistant against salt and frost. These pine trees grow in the coastal southwest France over 30–50 years, yielding consistent raw material. The purified aqueous extract is a reddish-brown fine powder which is soluble in water.

Pine bark is available in multiple forms including powders, tablets, capsules, solution, gummies, and teas. Pine bark extract is made from the bark of pine trees that grow in some Mediterranean countries. Pine bark extract supplements come as capsules, powders, and tablets. Pine needle preparations are additionally available as teas (infusions), tinctures (ethanolic extracts), and steam-distilled essential oils.

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2. Traditional and Historical Use

2.1 Ancient and Classical World

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. Ancient texts from multiple civilizations document pine's therapeutic role. In Turkish folk medicine, Pinus species have been used to treat rheumatic pain and for wound healing.

2.2 Native American Traditions

Native people across the continent — including the Cherokee, Chippewa, Iroquois, Apache, Hopi, and countless other groups — have used over twenty species of pine in a similar medicinal fashion. Indigenous cultures have long recognised the value of pine needle tea. For many Native American tribes, particularly the Haudenosaunee (Iroquois), pine trees held a special place in their traditions. They considered the white pine tree the "Tree of Peace" and used its needles to brew a nourishing tea. This practice was not only a part of their daily life but also played a crucial role in their medicinal traditions.

Native Americans drank warm infusions to promote respiratory health, or chewed the fresh needles for sore throats and oral hygiene. They made chewing gum from pine resin to soothe sore throats and created poultices from crushed pine needles to relieve headaches. Native American tribes employed pine needle teas and poultices to address respiratory ailments, arthritis, and skin conditions.

2.3 Scandinavian and Northern European Traditions

In Scandinavia and Northern Russia, pine needles were brewed into a restorative tea to maintain vitality and immunity through the cold winters. The bark and resin of Scots pine (Pinus sylvestris) have historically been used across Northern Europe as antimicrobial washes and expectorants.

2.4 East Asian Traditions

Pine needle tincture has been used for thousands of years in traditional Chinese medicine (TCM). In TCM, pine needle tincture is used to improve digestion, reduce inflammation, and manage pain. In China, there has been a long-standing view that pine needle may be used as a supplement material for medicines. For example, some of the recipes collected in the Great Dictionary of Chinese Herbs can treat injury, edema, eczema, chronic bronchitis, and insomnia, or prevent influenza and epidemic encephalitis. In Japan, the needles were used externally — in soothing baths and compresses to promote relaxation and relieve muscle pain.

2.5 Forms and Preparations in Traditional Use

Across cultures and periods, pine has been prepared in the following traditional forms:

• Infusions/teas: Needles steeped in hot water, consumed for respiratory ailments, colds, and as a general tonic.
• Poultices: Crushed or ground needles applied externally for headaches, skin infections, and joint inflammation.
• Tinctures: Alcoholic extracts of needles or bark, used internally for pain and inflammation.
• Resin/pitch: Applied directly or dissolved as an antimicrobial wash or wound sealant.
• Steam inhalation: Native American cultures traditionally used pine as herbal steam and incense for soothing respiratory issues, including relieving asthma and bronchitis, clearing the sinuses, and addressing respiratory infections.
• Baths: Needle-infused bathwater for muscle aches and general relaxation.

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3. Key Constituents and Active Compounds

3.1 Bark Extract Composition

The primary constituents of pine bark extracts are procyanidins and phenolic acids. More specifically, the aqueous extract of the bark of P. pinaster has a high concentration of polyphenols represented by a mixture of procyanidins (comprising catechin and epicatechin subunits with varying chain lengths), besides phenolic acids (gallic, ferulic, caffeic, and p-hydroxybenzoic acids), cinnamic acids and their glycoside forms, and taxifolin.

It contains low molecular weight compounds such as the flavonoids (+)-catechin, (−)-epicatechin, (+)-taxifolin, the benzoic acids protocatechuic acid, vanillic acid, gallic acid, and the cinnamic acids ferulic acid, caffeic acid or p-coumaric acid. These phenolic acids are present as glucosides, glucose esters, and as aglycons. In Pycnogenol®, higher molecular weight procyanidins predominate.

Pycnogenol® is standardized to contain 65–75% procyanidins, which are a variety of biopolymers consisting of catechin and epicatechin monomeric units. Procyanidin, the main active ingredient in pine bark extract, is a member of the proanthocyanidin class of flavonoids, a subgroup of polyphenols with potent antioxidant properties. Dietary sources include berries, apples, nuts, cinnamon, cocoa beans, and red wine.

3.2 Needle Composition

Proanthocyanidins are oligomers and polymers of flavan-3-ol monomer units. The most common classes of procyanidins consist of catechins, epicatechins, and/or their gallic acid esters. Pine needles also contain volatile terpenes — notably alpha-pinene — that contribute to the characteristic aroma and to respiratory and antimicrobial activities. Alpha-pinene, a terpene found in the needles, bark, and resin of pine trees, not only gives pine its characteristic fragrance, but also carries healing properties.

3.3 Pharmacokinetics

Based on plasma concentration profiles, it can be concluded that low molecular weight constituents of the extract, such as catechin, caffeic acid, ferulic acid, and taxifolin, are readily absorbed from the small intestine into systemic circulation. In contrast, larger procyanidin polymers undergo microbial metabolism in the gut. Active metabolites, produced by gut microbiota in the intestinal tract from oligomeric procyanidins, appear in blood 6 hours following ingestion and remain for at least 14 hours, providing a long-lasting flow of anti-inflammatory substances. Notably, the catechin-derived gut microbial metabolite 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone has gained particular interest as a bioactive species that may mediate some of Pycnogenol's systemic effects. The main route of elimination of constituents and metabolites of the French pine bark extract is renal excretion.

In studies simultaneously investigating concentrations in different specimens, a preferential distribution of individual compounds has been observed, e.g., of ferulic acid and 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone into synovial fluid compared to serum. This distribution into synovial fluid is particularly relevant to proposed mechanisms in osteoarthritis.

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4. Established and Proposed Mechanisms of Action

4.1 Antioxidant and Free Radical Scavenging

Pycnogenol is a complex mixture of bioflavonoids with reported protective effects against disease. It is an effective scavenger of reactive oxygen species, and its main constituents are procyanidins of various chain lengths. Investigations of the cellular mechanisms of these therapeutic effects have demonstrated that PYC has strong free radical-scavenging activity against reactive oxygen and nitrogen species.

There are three identified levels of antioxidant protection by procyanidins. There are three levels of mechanisms by which procyanidin can protect the body against oxidative stress: prevention, as antioxidants reduce hydroperoxides and hydrogen peroxide to alcohols and water, respectively. Additionally, proanthocyanidin binding of iron and copper, which are cofactors of several enzymes involved in oxygen metabolism, limits the formation of free radical reactions; direct inhibition of pro-oxidative enzymes such as lipoxygenase, nitric oxide synthase, and xanthine oxidase constitutes another arm of protection. Pycnogenol increases the activities of antioxidant enzymes by increasing the intracellular glutathione levels.

4.2 Anti-Inflammatory Mechanisms

In addition to increasing nitric oxide production which induces vasodilation, pine bark extract blocks the NF-κB activation stimulated by tumor necrosis factor-alpha (TNF-alpha) and inhibits production of adhesion proteins that cause inflammation and atherosclerosis. The inhibition of cartilage-destructing proteases and pain-producing cyclo-oxygenases provides the basis for relief from pain, improvement of stiffness, and enhanced mobility observed in osteoarthritis clinical studies.

4.3 Vascular and Endothelial Effects

PYC has been reported to have cardiovascular benefits, such as a vasorelaxant activity, angiotensin-converting enzyme (ACE) inhibiting activity, and the ability to enhance the microcirculation by increasing capillary permeability. Procyanidins inhibit thromboxane A2 synthesis, a key pathway in platelet activation, which contributes to the antithrombotic properties observed in preclinical and clinical work.

4.4 Glucose Metabolism

A possible mechanism to understand how Pycnogenol® contributes to lower blood glucose levels is that sugar absorption was slowed down in patients supplemented with Pycnogenol® by inhibition of α-glucosidase, the enzyme that disassembles starch.

4.5 Nitric Oxide Pathway (Erectile Function)

Nitric oxide (NO) is the messenger molecule of penile erection, which is produced by neuronal NO synthase of penile non-adrenergic, non-cholinergic nerve terminals and endothelial NOS of penile artery endothelial cells. After NO production, it binds to guanylate cyclase in the smooth muscle cells of the corpus cavernosum to generate cGMP. Increased cGMP leads to relaxation of vascular smooth muscle and increased blood flow into the corpus cavernosum. Pine bark extract's ability to stimulate endothelial NO production is considered a key mechanism in studies of erectile dysfunction.

4.6 Synergistic Effects

Uniquely, PYC displays greater biological effects as a mixture than its purified components do individually, indicating that the components interact synergistically.

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5. Scientific Evidence by Area of Use

5.1 Overview of the Clinical Evidence Base

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. However, overall evidence quality has important limitations. A Cochrane systematic review (updated 2020) found that 27 RCTs with 1,641 participants evaluated pine bark extract supplements across 10 chronic disorders: asthma (two studies; 86 participants); ADHD (one study; 61 participants), cardiovascular disease and risk factors (seven studies; 338 participants), chronic venous insufficiency (two studies; 60 participants), diabetes mellitus (six studies; 339 participants), erectile dysfunction (three studies; 277 participants), female sexual dysfunction (one study; 83 participants), osteoarthritis (three studies; 293 participants), osteopenia (one study; 44 participants), and traumatic brain injury (one study; 60 participants). While there have been many clinical trials of pine bark for these indications, all have been limited in size and duration of therapy. Most studies have shown only modest changes in clinical symptoms, physical signs, or biological features, and none have been considered definitive in demonstrating efficacy or safety.

5.2 Cardiovascular Health and Blood Pressure

In humans, Pycnogenol® has been shown to lower blood pressure in mild to moderate hypertensive individuals and blood glucose levels in diabetics. A PRISMA-compliant systematic review and meta-analysis of randomized, double-blind, placebo-controlled studies examined the effect of Pycnogenol on blood pressure specifically (Fogacci et al., 2020, published in Angiology). Additionally, a meta-analysis and systematic review of RCTs to evaluate cardiometabolic effects (Malekahmadi et al., 2019, Pharmacological Research) reported that Pycnogenol significantly reduced fasting blood glucose (WMD: −5.86 mg/dl), glycated hemoglobin (WMD = −0.29%), systolic blood pressure (WMD: −2.54 mmHg), diastolic blood pressure (WMD: −1.76 mmHg), body mass index (WMD: −0.47 kg/m²), LDL cholesterol (WMD: −7.12 mg/dl), and increased HDL cholesterol (WMD: 3.27 mg/dl). The authors concluded that this meta-analysis suggests pycnogenol may have a role in preventing cardiometabolic disease; however, further well-designed RCTs are recommended to evaluate its long-term effects and explore the optimal duration of use and dosage.

An earlier meta-analysis of 5 controlled studies (N=442) in various patient populations reported that lipid parameters (i.e., total cholesterol, HDL, triglycerides), excluding LDL, were not affected by supplementation with Pycnogenol. A significant dose-effect association was found for effects on LDL (slope, −0.007; P=0.01). Limitations of the analysis included observed effect sizes too small to be clinically relevant, lack of data on concomitant lipid-lowering drugs, and uncontrolled dietary measures. Evidence strength: Preliminary to moderate; effect sizes are statistically significant in some meta-analyses but clinically modest; larger confirmatory RCTs are lacking.

5.3 Chronic Venous Insufficiency (CVI)

Pine bark extract showed antioxidant, anti-inflammatory, immunostimulant, cardioprotective, and neuroprotective effects in preclinical studies. In a double-blind RCT of 40 patients with CVI and leg varices, participants received Pycnogenol® 100 mg three times daily or placebo for 2 months. Pycnogenol treatment induced a significant reduction in subcutaneous edema as well as heaviness and pain in the legs, at both 30 and 60 days. Approximately 60% of patients treated with Pycnogenol® experienced improvement. A comparative study found that after eight weeks of treatment, patients who supplemented with Pycnogenol® experienced decreased ankle swellings by 35 percent, while Daflon (a reference drug) decreased ankle swelling by 19 percent. Evidence strength: Positive signal in small RCTs; the Cochrane review included only two CVI studies totaling 60 participants, making definitive conclusions premature.

5.4 Osteoarthritis

This area of investigation summarizes the effects of the standardized proprietary bark extract of the French maritime pine (Pycnogenol®) in mild osteoarthritis (OA), stage 1 and 2. The extract exerts antioxidative, anti-inflammatory, and chondroprotective effects in vitro and in vivo. Three identically designed clinical trials investigating the role of Pycnogenol in OA treatment have been published. All studies were randomized, double blind, and placebo controlled. Middle-aged patients (48–54 years) suffering from mild OA, stage I or II, verified by X-ray, were treated either with 3 × 50 mg Pycnogenol daily or placebo, added to existing therapy with NSAIDs. Together, the three clinical studies demonstrate a highly significant improvement of symptoms of mild OA under Pycnogenol, despite the reduced intake of NSAIDs. No unwanted effects of Pycnogenol were reported in the three studies.

Pharmacokinetic evidence supports biological plausibility: constituents of Pycnogenol could be detected in serum, blood cells, and synovial fluid of OA patients. 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 overall, given small sample sizes and short trial durations. Evidence strength: Preliminary positive — three small RCTs show consistent symptomatic benefit; independent replication in larger trials is needed.

5.5 Diabetes and Blood Glucose Regulation

Pycnogenol® supplementation lowered glucose levels in plasma significantly by 22% in subjects with diabetes mellitus after three months. In a separate RDP study, Pycnogenol® was shown to lower glycated hemoglobin by 10% in the Pycnogenol® group, a significant effect compared to placebo. Fasting plasma glucose levels decreased significantly by 16.7% compared to baseline and by 18.4% compared to placebo. However, an umbrella review of herbal medicines for type 2 diabetes (Li et al., 2025, BMC Complementary Medicine and Therapy) concluded that the pine bark extract Pycnogenol had minimal effects on HbA1c and fasting blood glucose levels and had no reported serious adverse events. Evidence strength: Mixed; individual small RCTs show statistically significant glucose-lowering effects, but an umbrella review characterizes the overall glycemic impact as minimal. Effect sizes may not be clinically sufficient as standalone therapy.

5.6 Erectile Dysfunction

When used in conjunction with L-arginine, pycnogenol improved erectile dysfunction symptoms. A systematic review and meta-analysis (PMC10614297) searched seven databases and included three studies with 184 patients. The results showed that there were significant differences in the international index of erectile function scores (erectile domain), intercourse satisfaction scores, orgasmic function scores, overall satisfaction scores, and sexual desire scores between the combination treatment group and the control group. Studies investigating erectile function have commonly used pycnogenol doses between 100 mg and 120 mg daily, often in combination with L-arginine (1.7–3 g daily). However, optimal dosing has not been established through large-scale clinical trials. A meta-analysis showed that the combination of pine bark extract and arginine improved erectile dysfunction. Evidence strength: Preliminary, based on a small number of trials with modest participant numbers; a mechanistic rationale (endothelial NO stimulation) is supported by in vitro work, but independent large-scale RCTs are absent.

5.7 Cognition and Neurological Function

Pycnogenol may enhance memory in elderly participants, but studies in adults and children with ADHD yielded mixed results. A large RCT protocol — the Australian Research Council Longevity Intervention (ARCLI) study — described a trial in which 465 participants were to be randomized to receive Pycnogenol (150 mg/day) or placebo daily for 12 months to examine cognitive and cardiovascular outcomes. In vitro, pycnogenol reduced neuronal apoptosis, an important feature of Alzheimer's disease, by decreasing free radical generation. Evidence strength: Preliminary; in vitro neuroprotective data are available; human clinical evidence in cognition and ADHD is limited and has yielded mixed results.

5.8 Respiratory Health and Asthma

The Cochrane review included two asthma studies (N=86) among its 15 trials. Preclinical and ethnobotanical rationale for pine's use in respiratory conditions is strong, but human clinical evidence remains sparse. Evidence strength: Insufficient; only two small clinical trials have been conducted in asthma, precluding conclusions about efficacy.

5.9 Benign Prostatic Hyperplasia (BPH)

In a clinical study of 75 men with signs and symptoms of benign prostatic hyperplasia, Pycnogenol® 50 mg three times daily for 60 days significantly improved emptying, frequency, intermittency, urgency, weak flow, straining, and nocturia compared with a standard management group and a group receiving 5-alpha reductase inhibitor therapy. Evidence strength: Single small open-label clinical study; independent replication in blinded, placebo-controlled settings is required.

5.10 General Appraisal of Evidence Quality

Due to small sample size, limited numbers of trials per condition, variation in outcomes evaluated and outcome measures used, as well as the risk of bias in the included studies, no definitive conclusions regarding the efficacy or safety of Pycnogenol® are possible. Current evidence is insufficient to support Pycnogenol® use for the treatment of any chronic disorder. (This 2012 Cochrane conclusion preceded the expanded 2020 update but reflects a persistent finding.) Systematic reviews have concluded that evidence is insufficient and that large-scale studies are needed to establish the value of various pine bark extract supplements for chronic disorders.

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6. Body Systems and Health Areas Associated With Pine

Based on the aggregate of preclinical and clinical data, pine and pine bark extract have been investigated or used in association with the following body systems:

• Cardiovascular system: Blood pressure regulation, endothelial function, platelet aggregation, lipid profiles, capillary permeability, chronic venous insufficiency, and deep vein thrombosis prevention.
• Metabolic system: Blood glucose regulation, insulin sensitivity, and management of metabolic syndrome parameters including BMI and waist circumference.
• Musculoskeletal system: Osteoarthritis symptom management (pain, stiffness, mobility), muscle cramps, and osteopenia.
• Neurological system: Cognitive function, memory, ADHD, and neuroprotection (primarily preclinical).
• Reproductive/genitourinary system: Erectile dysfunction, female sexual dysfunction, sperm quality, and benign prostatic hyperplasia.
• Respiratory system: Asthma, bronchitis, and respiratory infections (primarily traditional use and limited clinical data).
• Skin and integument: Melasma, skin elasticity, and skin hydration.
• Women's health: Perimenopausal symptoms, dysmenorrhea, and osteopenia.
• Sports and physical performance: Pycnogenol®-supplemented cyclists rode 80 seconds longer until they reached exhaustion compared to subjects taking a placebo drink.
• Ocular system: Retinopathy (primarily small preliminary trials).

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7. Dosage Forms and Dosages Reported in Clinical Studies

In clinical trials, Pycnogenol® dosages ranged from 20 to 360 mg (or were weight based). The American Botanical Council states the most common duration of use in clinical trials was 2 to 3 weeks; however, longer-term use has been described.

The typical dose reported across trials is 100 to 400 mg daily.

The following indication-specific dosages were used in published clinical trials:

• ADHD: 1 mg/kg/day.
• Asthma: 100 mg/day.
• Chronic venous insufficiency: 150 to 360 mg/day.
• Diabetes: 50 to 200 mg/day.
• Erectile dysfunction: 120 mg/day (alone or combined with arginine).
• Hypertension: 100–200 mg/day.
• Melasma: 75 mg/day.
• Muscle cramps: 200 mg/day.
• Osteoarthritis: 3 × 50 mg per day (150 mg/day total); also reported at 100–150 mg/day.
• Perimenopause: 200 mg/day.
• Retinopathy: 20–160 mg/day.
• BPH: 50 mg three times daily (150 mg/day) for 60 days.
• Cardiovascular studies (general): 120 to 200 mg/day for durations of 2 to 24 weeks.

In the clinical trials, the most common duration of use was 2–3 months; however, long-term use may be justified. Based on the published chemistry, pharmacology, and toxicology of Pycnogenol®, there are no data suggesting a limitation on duration of use.

Most research on French maritime pine extract has used Pycnogenol®, as opposed to other standardized extracts such as Oligopin® and Flavangenol®. These extracts have slightly different chemical compositions, due to different extraction techniques, and there currently is not enough evidence to know whether Oligopin® and Flavangenol® work the same as Pycnogenol®.

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8. Safety Considerations and Drug Interactions

8.1 General Safety Profile

Pine bark is an extract from the bark of several species of pine trees (Pinus) used in traditional medicine to treat a wide variety of conditions. 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. A comprehensive review of 27 randomized controlled trials involving 1,641 participants across various chronic conditions found that pine bark extract supplements were generally safe, with few reports of serious adverse events or hospital admissions.

In animal safety studies, pine bark extract did not affect organ weights and liver-function indexes (activities of alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase) at doses of 0.04%, 0.4%, and 2.0% PBE in the diet, in normal and ovariectomized female mice.

8.2 Drug Interactions

Anticoagulant and/or antiplatelet drugs: Pine bark extract can inhibit platelet aggregation and may increase risk of bleeding when used with these drugs. Combining it with anticoagulant drugs (e.g., warfarin) or antiplatelet drugs (e.g., aspirin, clopidogrel) could increase the risk of bruising and bleeding. This risk is mechanistically grounded: procyanidins inhibit thromboxane A2 synthesis, a key pathway in platelet activation.

Because pine bark can help lower blood sugar levels, taking it alongside antidiabetic drugs (like insulin or metformin) may cause blood sugar to drop too low, leading to hypoglycemia.

Pine bark extract can potentially interfere with medications that suppress the immune system, decreasing their efficacy for those with autoimmune diseases or transplants.

Individuals taking blood pressure medication may experience an excessive drop in blood pressure if taking pine bark extract concurrently.

Combining pycnogenol (especially with L-arginine) and PDE5 inhibitors such as sildenafil could potentially cause additive blood pressure lowering effects.

In oncology contexts, herbs that exert antioxidant effects, such as grape seed and pine bark extracts, should be used with caution alongside anthracyclines, platinum compounds, alkylating agents, bleomycin, and epipodophyllotoxins — all of which generate free radicals for their cytotoxic effects — as antioxidants may theoretically interfere with their mechanisms.

8.3 Special Populations

Pregnant or breastfeeding women should avoid this supplement due to limited safety data. The concern is substantiated by ethnobotanical reports: throughout history, some indigenous cultures used certain pine species specifically to terminate pregnancies. Today's research shows that compounds like isocupressic acid can pose serious risks during all pregnancy stages.

People with autoimmune disorders should exercise caution, as the extract can stimulate the immune system and potentially worsen symptoms.

8.4 Adverse Effects Reported

Adverse effects in clinical trials have been infrequent and generally mild. Reported effects may include irritability and lower energy levels. Gastrointestinal upset (nausea, diarrhea) and headache have been noted in some participants in trials, though these were not consistently distinguished from placebo. A rare but serious side effect is an allergic reaction, especially for those sensitive to pine trees or related plants.

8.5 Variability Across Products

It is important to note that findings from studies of Pycnogenol® — a highly standardized, well-characterized extract — may not directly apply to other pine bark products, which can differ substantially in procyanidin content, extraction method, species of origin, and quality. There are many pine bark extracts on the market from different pine tree species, from different countries, and with different levels of efficacy for human health. Similarly, crude preparations such as pine needle teas lack the standardization of commercial bark extracts, and claims derived from bark extract research should not automatically be extrapolated to needle-based preparations.

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References

• Frontiers in Nutrition (2024): Pycnogenol® French maritime pine bark extract in randomized, double-blind, placebo-controlled human clinical studies
• Frontiers in Nutrition (2024): Review of the pharmacokinetics of French maritime pine bark extract (Pycnogenol®) in humans — PMC
• PMC / Cochrane (2020): Pine bark (Pinus spp.) extract for treating chronic disorders — updated Cochrane review
• PubMed (2012): Pycnogenol® (extract of French maritime pine bark) for the treatment of chronic disorders — original Cochrane review
• NIH/NCBI LiverTox: Pine Bark — NCBI Bookshelf
• Memorial Sloan Kettering Cancer Center: Pine Bark Extract — Herb/Supplement Monograph
• PubMed (1999): Antioxidant activity and biologic properties of a procyanidin-rich extract from pine (Pinus maritima) bark, pycnogenol
• PubMed (2000): Enzyme inhibition and protein-binding action of the procyanidin-rich French maritime pine bark extract, pycnogenol: effect on xanthine oxidase
• PMC (2018): Review on Sustained Relief of Osteoarthritis Symptoms with a Proprietary Extract from Pine Bark, Pycnogenol
• PMC (2017): Distribution of Constituents and Metabolites of Maritime Pine Bark Extract (Pycnogenol®) into Serum, Blood Cells, and Synovial Fluid of Patients with Severe Osteoarthritis — RCT
• PubMed (2000): Pycnogenol in chronic venous insufficiency
• PMC (2023): Efficacy of L-arginine and Pycnogenol® in the treatment of male erectile dysfunction: a systematic review and meta-analysis
• PMC (2011): Antioxidant activity and analysis of proanthocyanidins from pine (Pinus densiflora) needles
• PMC (2010): Comparison of methods for proanthocyanidin extraction from pine (Pinus densiflora) needles and biological activities of the extracts
• PubMed (2010): Identification of polymeric procyanidins from pine bark by mass spectrometry
• PMC (2012): ARCLI study protocol — RCT investigating Pycnogenol and Bacopa on cognitive and cardiovascular outcomes
• Examine.com: Pycnogenol — evidence summary, dosage, and side effects
• Drugs.com Natural Product monograph: Pine Bark Extract — Uses, Benefits, and Dosage
• PMC (2015): Protective effects of pine bark extract against cisplatin-induced hepatotoxicity and oxidative stress in rats
• ResearchGate: A review of the French Maritime Pine Bark Extract (Pycnogenol), a herbal medication with diverse clinical pharmacology
• PMC (2025): Ultrasound-Assisted Extraction of Bioactive Compounds From Black Pine (Pinus nigra) Bark: Optimization and Evaluation of Their In Vitro Bioactivities
• Chestnut School of Herbal Medicine: The Medicine of Pine