Pycnogenol is a standardized pine bark extract derived specifically from French maritime pine trees (Pinus pinaster) found on the coast of France. It provides a concentrated source of flavonoids and phenolic acids, including procyanidin oligomers (65–75% by weight), catechin, epicatechin, taxifolin, caffeic acid, and ferulic acid. While other French maritime pine bark extracts exist (oligopin and flavangenol), their composition varies slightly due to different extraction techniques. Pycnogenol has been used in the vast majority of clinical trials to date, and will be the focus of this page unless otherwise mentioned.

Pycnogenol possesses anti-inflammatory, antioxidant, and vasoactive properties that may beneficially impact various health conditions. Despite some promising results, most health outcomes are supported by just a handful of small trials, and many of the existing trials have a high risk of bias.

Pycnogenol may reduce the signs and symptoms of chronic venous insufficiency (e.g., leg pain, heaviness, and edema; venous ulcers; microangiopathy)^[4][5][6][7] and reduce leg edema and blood clot risk during long-duration air travel (although the latter has only been observed in a single trial).^[8][9]

Short-term (≤3 months) trials have found that pycnogenol may reduce pain, improve physical functioning, and reduce the use of non-steroidal anti-inflammatory drugs (NSAIDs) in people with osteoarthritis.^{[10][11][12][13]} Interestingly, research suggests that some compounds in pycnogenol can enter the synovial fluid in joints, where they may act locally to reduce inflammation and inhibit the breakdown of collagen.^[14][15][16]

Pycnogenol is generally considered safe and well tolerated. Side effects occur rarely and may include headache, dizziness, drowsiness, skin irritation, and gastrointestinal upset (e.g., nausea), the latter of which may improve if pycnogenol is taken with food.^[1]

Most of the research on pycnogenol has been at least partially funded by the manufacturer of pycnogenol. While this doesn’t invalidate the research, it does make it more prone to bias in favor of pycnogenol.

The biological activity of pycnogenol is due to its diverse and rich content of polyphenols.^[17] Following ingestion, some of these compounds are metabolized by bacteria in the colon into other bioactive compounds that can be absorbed. For example, bacteria can convert the procyanidins in pycnogenol into the compound M1 (δ-(3,4-dihydroxy-phenyl)-γ-valerolactone), which is thought to strongly contribute to its overall biological effects.^[18][19]

Pycnogenol seems to decrease pain and inflammation by reducing the activity of certain pathways in the body that lead to the production of pro-inflammatory compounds, including nuclear factor kappa B (NF-κB) and cyclooxygenase (COX)-1 and COX-2 enzymes.^[15][20] As an antioxidant, in vitro and animal research suggests that pycnogenol may directly scavenge free radicals, regenerate other antioxidants in the body (e.g., vitamin C, vitamin E, and glutathione), and increase the activity of antioxidant enzymes.^[21][22][23] The above effects, as well as pycnogenol's ability to enhance nitric oxide synthesis and increase capillary integrity, may contribute to reduced capillary permeability and increased blood flow.^[24][7]