Oligomeric Proanthocyanidins (OPCs)

Supplement Forms/Alternate Names:

  • Grape seed extract
  • Pine bark extract
  • French maritime pine bark
  • Procyanidolic oligomers (PCOs)
  • Pycnogenol


Oligomeric proanthocyanidins (OPCs) are compounds found in grape seed and pine bark extracts. They have been used to improve blood flow, reduce symptoms of diabetes, and to ease swelling in the joints. OPCs have also been used to improve vein function to ease swelling. They can be taken by using either grape seed or pine bark. Grape seed and pine bark can both be taken as pill, powder, or extract. They can also be used as a gel or oil.


There are no advised doses for OPCs.

What Research Shows

May Be Effective

May Not Be Effective

Not Enough Data to Assess

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.
Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe to use OPCs on the skin or take them orally in small doses for a short time. Not enough studies have been done to say whether they are safe to use for a long period. It is also not known whether it is safe to take by women who are pregnant or breastfeeding.
Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.


A Attention Deficit/Hyperactivity Disorder
A1 Trebatická J, Kopasová S, et al. Treatment of ADHD with French maritime pine bark extract, Pycnogenol. Eur Child Adolesc Psychiatry. 2006;15(6):3290335. A2. Sarris J, Kean J, et al. Complementary medicines (herbal and nutritional products) in the treatment of Attention Deficit Hyperactivity Disorder (ADHD): a systematic review of the evidence. Complement Ther Med. 2011 Aug;19(4):216-227. A3. Anheyer D, Lauche R, et al. Herbal medicines in children with attention deficit hyperactivity disorder (ADHD): A systematic review. Complement Ther Med. 2017 Feb;30:14-23.
B Bone Loss After Menopause
B1 Panahande SB, Maghbooli Z, et al. Effects of French maritime pine bark extract (Oligopin®) supplementation on bone remodeling markers in postmenopausal osteopenic women: A randomized clinical trial. Phytother Res. 2019 Apr;33(4):1233-1240.
C Cancer Treatment Support
C1 Brooker S, Martin S, et al. Double-blind, placebo-controlled, randomised phase II trial of IH636 grape seed proanthocyanidin extract (GSPE) in patients with radiation-induced breast induration. Radiother Oncol. 2006 Apr;79(1):45-51.
D Cardiovascular Disease Risk
D1 Kar P, Laight D, et al. Effects of grape seed extract in Type 2 diabetic subjects at high cardiovascular risk: a double blind randomized placebo controlled trial examining metabolic markers, vascular tone, inflammation, oxidative stress and insulin sensitivity. Diabet Med. 2009 May;26(5):526-531.
D2 Drieling RL, Gardner CD, et al. No beneficial effects of pine bark extract on cardiovascular disease risk factors. Arch Intern Med. 2010 Sep 27;170(17):1541-1547.
D3 Valls RM, Llauradó E, et al. Effects of low molecular weight procyanidin rich extract from french maritime pine bark on cardiovascular disease risk factors in stage-1 hypertensive subjects: Randomized, double-blind, crossover, placebo-controlled intervention trial. Phytomedicine. 2016 Nov 15;23(12):1451-1461.
E Chronic Disorders
E1 Schoonees A, Visser J, et al. Pycnogenol® (extract of French maritime pine bark) for the treatment of chronic disorders. Cochrane Database Syst Rev. 2012 Apr 18;(4):CD008294.
F Dysmenorrhea
F1 Suzuki N, Uebaba K, et al. French maritime pine bark extract significantly lowers the requirement for analgesic medication in dysmenorrhea: a multicenter, randomized, double-blind, placebo-controlled study. J Reprod Med. 2008 May;53(5):338-346.
G Gingivitis
G1 Díaz Sánchez RM, Castillo-Dalí G, et al. A Prospective, Double-Blind, Randomized, Controlled Clinical Trial in the Gingivitis Prevention with an Oligomeric Proanthocyanidin Nutritional Supplement. Mediators Inflamm. 2017;2017:7460780.
H High Blood Pressure
H1 Sivaprakasapillai B, Edirisinghe I, et al. Effect of grape seed extract on blood pressure in subjects with the metabolic syndrome. Metabolism. 2009 Dec;58(12):1743-1746.
H2 Feringa HH,Laskey DA, et al. The effect of grape seed extract on cardiovascular risk markers: a meta-analysis of randomized controlled trials. J Am Diet Assoc. 2011;111(8):1173-1181.
H3 Ras RT, Zock PL, et al. Effect of polyphenol-rich grape seed extract on ambulatory blood pressure in subjects with pre- and stage I hypertension. Br J Nutr. 2013 Dec;110(12):2234-2241.
H4 Park E, Edirisinghe I, et al. Effects of grape seed extract beverage on blood pressure and metabolic indices in individuals with pre-hypertension: a randomised, double-blinded, two-arm, parallel, placebo-controlled trial. Br J Nutr. 2016 Jan 28;115(2):226-38.
H5 Zhang H, Liu S, et al. The impact of grape seed extract treatment on blood pressure changes: a meta-analysis of 16 randomized controlled trials. Medicine (Baltimore) 2016;95(33):e4247.
I High Cholesterol
I1 Razavi SM, Gholamin S, et al. Red grape seed extract improves lipid profiles and decreases oxidized low-density lipoprotein in patients with mild hyperlipidemia. J Med Food. 2013 Mar;16(3):255-258.
J Knee Osteoarthritis
J1 Cisár P, Jány R, et al. Effect of pine bark extract (Pycnogel) on symptoms of knee osteoarthritis. Phytother Res. 2008;1087-1092.
K Menopause
K1 Yang HM, Liao MF, et al. A randomised, double-blind, placebo-controlled trial on the effect of Pycnogenol on the climacteric syndrome in peri-menopausal women. Acta Obstet Gynecol Scand. 2007;86(8):978-985.
K2 Kohama T, Negami M. Effect of low-dose French maritime pine bark extract on climacteric syndrome in 170 perimenopausal women: a randomized, double-blind, placebo-controlled trial. J Reprod Med. 2013 Jan-Feb;58(1-2):39-46.
K3 Terauchi M, Horiguchi N, et al. Effects of grape seed proanthocyanidin extract on menopausal symptoms, body composition, and cardiovascular parameters in middles-aged women: a randomized, double-blind, placebo-controlled pilot study. Menopause. 2014;21(9):990-996.
L Migraine
L1 Chayasirisobhon S. Use of a pine bark extract and antioxidant vitamin combination product as therapy for migraine in patients refractory to pharmacologic medication. Headache. 2006 May;46(5):788-793.
M Periodontitis
M1 Rayyan M, Terkawi T, et al. Efficacy of grape seed extract gel in the treatment of chronic periodontitis: A randomized clinical study. J Investig Clin Dent. 2018;9(2):e12318.
N Photoaged Facial Skin
N1 M, Sato N, et al. Oral administration of French maritime pine bark extract (Flavangenol(®)) improves clinical symptoms in photoaged facial skin. Clin Interv Aging. 2012;7:275-286.
O Post-Thrombotic Syndrome Prevention
O1 Errichi BM, Belcaro G, et al. Prevention of post thrombotic syndrome with Pycnogenol® in a twelve month study. Panminerva Med. 2011 Sep;53(3 Suppl 1):21-27.
P Venous Insufficiency
P1 Cesarone MR, Belcaro G, et al. Improvement of signs and symptoms of chronic venous insufficiency and microangiopathy with Pycnogenol: a prospective, controlled study. Phytomedicine. 2010 Sep;17(11):835-839.
P2 Martinez-Zapata MJ, Vernooij RW, et al. Phlebotonics for venous insufficiency. Cochrane Database Syst Rev. 2016 Apr 6;4:CD003229.
Q Wound Healing
Q1 Hemmati AA, Foroozan M, et al. The topical effect of grape seed extract 2% cream on surgery wound healing. Glob J Health Sci. 2014 Oct 29;7(3):52-58.
Q2 Izadpanah A, Soorgi S, et al. Effect of grape seed extract ointment on cesarean section wound healing: A double-blind, randomized, controlled clinical trial. Complement Ther Clin Pract. 2019 May;35:323-328.

Revision Information

  • Reviewer: EBSCO NAT Review Board Eric Hurwitz, DC
  • Review Date: 03/2020
  • Update Date: 06/29/2020