Oligomeric Proanthocyanidins (OPCs) Usage

The best-documented use of OPCs is to treat chronic venous insufficiency , a condition closely related to varicose veins. In both of these conditions, blood pools in the legs, causing aching, pain, heaviness, swelling, fatigue, and unsightly visible veins. Fairly good preliminary evidence suggests that OPCs from pine bark or grape seed can relieve the leg pain and swelling of chronic venous insufficiency. ^{1 2 3 4} However, no studies have evaluated whether regular use of OPCs can make visible varicose veins disappear, or prevent new ones from developing.

Other small, double-blind trials suggest that OPCs may help reduce swelling caused by injuries or surgery . ^{5 6} Evidence from one small, double-blind trial suggests that OPCs from bilberry and grape seed may reduce the general fluid retention and swelling that can occur in premenstural syndrome (PMS) . ⁷ One large study found some evidence that use of OPCs from pine bark might help prevent the leg blood clots that can develop on a long airplane flight. ⁸ Two preliminary studies found evidence that OPCs from pine bark, alone or with arginine , may be helpful for impotence . ⁹ In a double-bind, placebo-controlled study of 61 children with attention deficit hyperactivity disorder (ADHD) , use of OPCs from pine bark (at a dose of 1 g per kg per day) appeared to improve some measurements of disease severity. ¹⁰ Two small, double-blind pilot studies suggest that OPCs from pine bark might help reduce asthma symptoms. ¹¹ OPCs are also often recommended for allergies , but an 8-week, double-blind trial of 49 individuals found no benefit with grape seed extract. ¹² OPCs might marginally improve blood sugar control in people with diabetes, according to a double-blind study of 77 people with type 2 diabetes. ¹³ Some evidence suggests that OPCs protect and strengthen collagen and elastin. ^{14 15 16 17 18} Theoretically, this could mean that OPCs are helpful for aging skin , and they are widely sold for this purpose, but there is as yet no direct evidence that the herbs work.

On the basis of their use in the treatment of varicose veins, OPCs are often recommended as a treatment for hemorrhoids as well, but there is no direct evidence to support this use. (Hemorrhoids are varicose veins in and around the anus.)

One study suggests that while OPCs alone may not reduce levels of cholesterol , some benefits may occur when taken in combination with chromium. ¹⁹ OPCs are strong antioxidants. Vitamin E defends against fat-soluble oxidants, and vitamin C neutralizes water-soluble ones, but OPCs are active against both types. ^{20 21} Based on the (unproven) belief that antioxidants offer many health benefits, regular use of OPCs has been proposed as a measure to prevent cancer , diabetic neuropathy and diabetic retinopathy , ²² and heart disease . ^{23 24 25} OPCs have been tried as a treatment for impaired night vision , ²⁶ lupus (systemic lupus erythematosus), ²⁷ easy bruising , ²⁸ high blood pressure , ²⁹ and liver cirrhosis . ³⁰ However, more research needs to be performed to discover whether it actually provides any benefits in these conditions.

A double-blind, placebo-controlled study of questionable validity reported that use of OPCs from pine bark produced benefits in allsymptoms of menopause . ³¹ One study failed to find OPCs significantly helpful for weight loss . ³² Another failed to find OPCs helpful for reducing the side effects of radiation therapy for breast cancer. ³³