Pine Bark Extract for Osteoarthritis

Pine bark extract, tested almost entirely as the French maritime pine product Pycnogenol, has been studied for osteoarthritis in a handful of small trials. In one, 100 adults with mild to moderate knee osteoarthritis took 150 mg a day or placebo for 3 months; pain and WOMAC scores (a standard pain, stiffness and function questionnaire) improved with the extract, and painkiller use fell [1]. A second placebo-controlled trial of 156 people reported a 56% drop in WOMAC score with 100 mg a day versus 9.6% with placebo [2].

The catch is certainty. A 2020 Cochrane review counted three osteoarthritis trials (293 participants) and could not say whether pine bark extract reduces WOMAC scores or anti-inflammatory drug use: the evidence was very low certainty, and small trials and poor reporting ruled out firm conclusions [3]. Treat it as a possible add-on to standard care for mild knee osteoarthritis, not a proven treatment.

Osteoarthritis involves enzymes that break down cartilage and low-grade inflammation inside the joint. Two reports, each on 33 people awaiting knee replacement and sharing authors, gave Pycnogenol for 3 weeks before surgery and then sampled the joint. Pine bark polyphenols, including taxifolin, ferulic acid and a gut-microbe metabolite of catechin, turned up in the synovial fluid (the fluid that lubricates the joint), although levels varied widely between people [4].

In the same setting, 200 mg a day lowered the activity of cartilage-degrading genes in chondrocytes (cartilage cells), with significant falls in MMP3, MMP13 and the inflammatory signal IL1B, and blood levels of the cartilage-degrading enzyme ADAMTS-5 fell too [5].

In a subset of one trial with raised C-reactive protein (CRP, a blood marker of inflammation), CRP fell from 3.9 to 1.1 mg/l with Pycnogenol versus 3.9 to 3.6 mg/l with placebo, and fibrinogen and plasma free radicals fell as well [6].

These are laboratory markers measured over 3 weeks to 3 months. The cartilage studies had no placebo group and measured no symptoms [5][4], and no randomised trial has imaged the joint to show slower cartilage loss. A plausible mechanism makes a benefit more believable; it does not show the extract protects joints.

The knee trials used 150 mg a day with meals [1] or 100 mg a day [2], each for 3 months. The pre-surgery studies used 200 mg a day (100 mg twice daily) for 3 weeks [5][4], and a hand osteoarthritis registry used 150 mg a day for 4 weeks [7].

All of these used Pycnogenol, a standardised extract. Generic pine bark products are not necessarily equivalent, so look for an extract standardised for procyanidins if you want to match the trials. Some products combine pine bark with other ingredients; those combinations have their own small studies [8][9] and the results do not transfer to pine bark alone.

In a double-blind trial, 100 adults with stage I-II knee osteoarthritis took 150 mg Pycnogenol a day or placebo for 3 months. WOMAC scores improved (p < 0.05) and pain on a visual analogue scale eased (p < 0.04) with the extract, while placebo had no effect; painkiller use fell with Pycnogenol and rose with placebo [1]. The abstract reports P values but not the size of the difference between groups.

In the SVOS trial, 156 people with osteoarthritis took 100 mg a day or placebo for 3 months. The global WOMAC score fell 56% with Pycnogenol versus 9.6% with placebo; treadmill walking distance rose from 68 m to 198 m (versus 65 m to 88 m on placebo); and anti-inflammatory drug use fell 58% versus 1% [2].

Cochrane's 2020 review included three osteoarthritis trials with 293 participants. Only one trial of 37 people could be used for its WOMAC estimate, and the review rated the evidence on both WOMAC and NSAID use as very low certainty. Across all conditions it concluded that no definitive conclusions on efficacy or safety were possible [3].

A 2018 meta-analysis of oral supplements for hand, hip and knee osteoarthritis listed pycnogenol among seven supplements with large, clinically important effects on pain in the short term. It also found the overall quality of evidence very low, and no supplement had clinically important effects on pain at long-term follow-up [12]. Memorial Sloan Kettering's monograph describes the osteoarthritis data as preliminary and notes that another meta-analysis recommended against pycnogenol for musculoskeletal pain [11].

The rest of the evidence is weaker. A 4-week registry in 42 people with painful hand osteoarthritis reported less pain and fewer people needing painkillers (2 of 22 vs 8 of 20) with 150 mg a day added to standard care, but it was not randomised or blinded [7]. Two combination products also have small studies: pine bark with Centellicum in a 6-month registry that reported better ultrasound cartilage thickness and surface regularity than standard care alone [9], and pine bark with mineral-rich algae and magnesium, which beat glucosamine on pain in a 30-person pilot [8].

Missing: larger trials longer than 3 months, trials in hip osteoarthritis, and imaging of cartilage in a placebo-controlled design. One research group, Belcaro and Cesarone's, ran the SVOS trial, its CRP sub-analysis and both registries [2][6][7][9], so more independent replication would help. Better-studied options include boswellia and undenatured type II collagen.

Tolerability looked good in the osteoarthritis studies: the 150 mg trial reported it was well tolerated [1], the hand osteoarthritis registry observed no side effects [7], and in the SVOS trial gastrointestinal complications fell by 63% with Pycnogenol, likely because people used fewer NSAIDs [2]. Memorial Sloan Kettering lists irritability and lower energy as possible reactions in its professional monograph [11].

Trials lasted 6 months at most, so long-term safety is unknown, and Cochrane noted that safety reporting across pine bark trials was too poor for firm conclusions [3].

The documented interaction is with anticoagulant and antiplatelet drugs, because pine bark can inhibit platelet aggregation [11]. In the osteoarthritis trials people could keep their usual anti-inflammatory medicines, and their use fell with pine bark [1][2]; no study looked for an interaction with NSAIDs.