Oligomeric Proanthocyanidins (OPCs) Overview

One of the bestselling herbal products of the early 1990s was an extract of the bark of French maritime pine. This substance consists of a family of chemicals known scientifically as oligomeric proanthocyanidin complexes (OPCs) or procyanidolic oligomers (PCOs). Similar (but not identical) substances are also found in grape seed. The research record is complicated by the fact that certain identically named proprietary products have consisted at different times of various proportions of these related substances.

OPCs are marketed for a wide variety of uses. As yet, however, there is no solid evidence that they are effective for any medical condition.

OPCs aren't a single chemical, but a group of closely related compounds. Several food sources contain similar chemicals: red wine, cranberries, blueberries, bilberries, tea (green and black), black currant, onions, legumes, parsley, and the herb hawthorn . However, most OPC supplements are made from either grape seed or the bark of the maritime pine. These two OPC sources lead to products that are not necessarily identical in function, although there do seem to be many similarities. In the discussion of scientific studies below, we indicate the source of the OPCs used when it is possible to do so. In some cases, however, identifying the exact product is difficult, as both grape seed and pine bark OPCs, or their combination, have at various times been sold under the same name.

For the treatment of specific medical conditions, studies have used doses of 150 to 300 mg daily. For use as a general antioxidant, 50 mg of OPCs daily are often recommended; however, there is no evidence that this dose provides any health benefits.

Venous Insufficiency (Varicose Veins)

There is fairly good preliminary evidence for the use of OPCs to treat people with symptoms of venous insufficiency .

A double-blind, placebo-controlled study of 71 subjects found that grape seed OPCs, taken at a dose of 100 mg 3 times daily, significantly improved major symptoms, including heaviness, swelling, and leg discomfort. ¹ Over a period of 1 month, 75% of the participants treated with OPCs improved substantially. This result doesn't seem quite so impressive when you note that significant improvement was also seen in 41% of the placebo group; nonetheless, OPCs still did significantly better than placebo.

A 2-month, double-blind, placebo-controlled trial of 40 people with chronic venous insufficiency found that 100 mg of pine bark OPCs 3 times daily significantly reduced edema, pain, and the sensation of leg heaviness. ² A similar study of 20 individuals also found OPCs from pine bark effective. ³ A placebo-controlled study (blinding not stated) that enrolled 364 people with varicose veins found that treatment with grape seed OPCs produced statistically significant improvements as compared to baseline. ⁴ There was a lesser response in the placebo group, but whether this difference was statistically significant was not stated.

OPCs have also been compared against other natural treatments for venous insufficiency. A double-blind study of 50 people with varicose veins of the legs found that doses of 150 mg per day of grape seed OPCs were more effective in reducing symptoms and signs than the bioflavonoid diosmin . ⁵ Similarly, a double-blind study of 39 people found pine bark OPCs more effective than the herb horse chestnut . ⁶

Edema After Surgery or Injury

Breast cancer surgery often leads to swelling of the arm. A double-blind, placebo-controlled study of 63 post-operative breast cancer patients found that 600 mg of grape seed OPCs daily for 6 months reduced edema, pain, and peculiar sensations known as paresthesias. ⁷ Also, in a double-blind, placebo-controlled study of 32 people who had received facial surgery, edema disappeared much faster in the group treated with grape seed OPCs. ⁸ Another 10-day, double-blind, placebo-controlled study enrolling 50 participants found that grape seed OPCs improved the rate at which edema disappeared following sports injuries . ⁹

Blood Clots After Plane Flights

It is commonly thought, though not proven, that the immobility endured during a long plane flight can lead to the development of potentially dangerous blood clots in the legs known as DVTs . ¹⁰ Travelers at high risk are often recommended to take aspirin to "thin" their blood prior to flying.

One crossover study of 22 smokers found that 100 mg of OPCs had an equivalent blood thinning effect as 500 mg of aspirin. ¹¹ On the basis of this, a large double-blind study was performed to evaluate whether OPCs from pine bark could help reduce risk of blood clots on long airplane flights. ¹² The study followed 198 people thought to be at high risk for blood clots. Some participants were given 200 mg of OPCs 2 to 3 hours prior to the flight, 200 mg 6 hours later, and 100 mg the next day; while others received placebo at the same schedule. The average flight length was about 8 hours. The results indicated that use of OPCs significantly reduced risk of blood clots. There were five cases of DVTs or superficial thrombosis in the placebo group, as compared to none in the OPC group, a difference that was statistically significant.

Another substantial double-blind study (204 participants) found benefit with a product that contains OPCs combined with nattokinase. ¹³ Nattokinase, also known as natto, is an extract of fermented soy thought to have some blood clot dissolving properties.

Periodontal Disease

Inflammation of the gums (gingivitis) and plaque formation lead to periodontal disease , one of the most common causes of tooth loss. A 14-day, double-blind, placebo-controlled trial of 40 people evaluated the potential benefits of a chewing gum product containing 5 mg of OPCs from pine bark. ¹⁴ Use of the OPC gum resulted in significant improvements in gum health and reductions in plaque formation; no similar benefits were seen in the placebo group.

Atherosclerosis

Although there are no reliable human studies, animal evidence suggests that OPCs can slow or reverse atherosclerosis . ^{15 16 17} This suggests (but definitely does not prove) that OPCs might be helpful for preventing heart disease.

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