This section is a list of chemical entities identified in this dietary supplement to possess pharmacological activity. This list does not imply that other, yet unidentified, constituents do not influence the pharmacological activity of this dietary supplement nor does it imply that any one constituent possesses greater influence on the overall pharmacological effect of this dietary supplement.
Proanthocyanidins also known as leucocyanidins or procyanidolic oligomers (PCOs).(1
Condensed tannins termed oligomeric proanthocyanidins (OPCs), or procyanidolic oligomers (PCOs), are the main active constituents found in grape seed and are possibly some of the most important natural products to be discovered in the last several years. They are flavonoid-rich compounds, which are being heavily regarded as some of the most potent antioxidants found in nature. An in vitro
study reported that OPCs contained in grape seed are approximately 2 times more powerful than vitamin E and as much as 4 times stronger than vitamin C.(2
) They may enhance absorption of and work synergistically with vitamin C, and have been reported to actually spare vitamin E from oxidation in vitro
) Activity of these OPCs include antibacterial, antiviral, anticarcinogenic, anti-inflammatory, anti-allergic, and vasodilatory.(4
) In addition, they have been found to inhibit lipid peroxidation, platelet aggregation, capillary permeability and fragility, and to affect enzyme systems including phospholipase A2, xanthine oxidase, cyclooxygenase, and lipoxygenase. Proanthocyanidins have been associated with the term "French Paradox," or the observation that a high dietary intake of fats in France is not associated with an increase in atherosclerosis and other cardiovascular diseases.(5
Interactions and Depletions
25-100mg (standardized extract), 1-3 times a day.
50mg (standardized extract), 2 times a day.
*Standardization represents the complete body of information and controls that serve to enhance the batch to batch consistency of a botanical product, including but not limited to the presence of a marker compound at a defined level or within a defined range.
The most current available medical and scientific literature indicates that the dietary supplement should be standardized to a procyanidolic value of greater than 95% or at least 80% proanthocyanidins or 95% polyphenols per dose.
Frequently Reported Uses
Other Reported Uses
- Improves Capillary Fragility And Permeability
- Improves Elastic Fibers Of Collagen And Elastin Of Capillaries
- Improves Microcirculation To The Brain, Heart, Periphery
- Retinopathy, Macular Degeneration
- Atherosclerosis Prevention
- Decreases Platelet Aggregation, Improves Blood Flow
- Arterial Or Venous Insufficiency, Intermittent Claudication
- Preventative, Anti-Aging Effects
No known toxicity or adverse effects even under high doses.(6
Based on pharmacology, use with caution in individuals with bleeding disorders.
If pregnant or nursing, consult a physician before use.
Do not use in children under 2 years of age unless recommended by a physician.
OPCs found in grape seed are antioxidants, or free radical scavengers.(7
) Free radical damage has been associated with nearly every chronic degenerative disease, including cardiovascular diseases, arthritis, hypercholesterolemia and cancer.(8
Proanthocyanidins are claimed to support collagen structures and inhibit the destruction of collagen, strengthening capillary walls and other vessels.(9),(10) Collagen protection is claimed to be very important for health because it allows red blood cells to penetrate into the microcapillary system and prevent fluids from leaking out of the microvasculature.(11),(12) OPCs reportedly protect 1-antitripsin, a chemical that keeps enzymes from breaking down collagen, elastin and hyaluronic acid(13),(14) and directly inhibits these substances from damaging enzymes. OPCs have also been reported to decrease edema, based upon the stabilization of the capillary wall and prevention of the increase in capillary permeability.(15),(16),(17) In one double-blind, placebo controlled study, 71 patients with peripheral venous insufficiency received grape seed extract (300mg OPCs) or placebo daily.(18) The individuals receiving the grape seed extract reported a 75% reduction in the symptoms associated with venous insufficiency. Another report of a single administration of OPCs (150mg) resulted in an increase in venous tone in patients with varicosities.(19) Similarly, a double blind, placebo controlled study of elderly individuals with either spontaneous or drug-induced low capillary resistance were treated with OPCs from grape seed (100-150mg) or placebo.(20) The study results reported a noticeable improvement (53% of treated individuals) in capillary resistance after two weeks of therapy.
The OPCs of grape seed have also been reported to have PAF inhibiting ability in laboratory studies, with potency comparable to that of aspirin.(21) The inhibitory effect of OPCs on thromboxane biosynthesis may explain the platelet aggregation inhibiting activity. Grape seed extract proved to be beneficial in lowering blood pressure in patients with metabolic syndrome.(22)
Proanthocyanidins contained in grape seed are reported to neutralize lipid peroxidation damage to cell membranes through their free radical scavenging activity, including hydroxyl, lipid peroxides and iron-induced lipid peroxidation.(23),(24),(25),(26),(27),(28) This effect may be useful in protection from elevated cholesterol levels. A laboratory animal study reported that a single dose proanthocyanidins from grape seeds increased the resistance of blood plasma against oxidative stress.(29) A study involving 8 healthy volunteers found that grape seed extract enhanced the resistance to oxidative modificaton of LDL.(30) A randomized, double-blind, crossover study with 24 healthy male heavy smokers, aged 50 and over showed grape seed extract slowed oxidation of low density lipoprotein.(31)
OPCs have been reported effective in improving the visual performances after glare as well as the visual adaptation.(32) An open trial of 147 individuals with retinopathy were administered OPCs from grape seed (100mg) daily.(33) The authors reported successful treatment of exudations secondary to hypoxia. The matrix metalloproteinases (MMP's), a protein which plays a key role in the extracellular matrix turnover, is thought to be involved in ocular pathologies such as glaucoma, diabetic retinopathy, macular degeneration, vitreous degeneration and corneal stroma ulceration.(34) An in vitro study using OPCs from grape seed was reported to inhibit this type III collegenase activity and may be beneficial in reducing the damaging effects on ocular structures.(35)
Grape seed proanthocyanidins were recently reported to be cytotoxic in vitro against some cancer cell lines, including MCF-7 human breast cancer cells, A-427 human lung cancer cells and CRL-1739 human gastric adenocarcinoma.(36) Also, the grape seed extract enhanced the growth and viability of the normal human gastric mucosal cells and murine macrophage cells. Grape seed proanthocyanidins were also reported to have radioprotective activity, decreasing the damaging effects of radiation in an in vitro study.(37) Another in vitro study reported that OPCs from grape seed were effective in reducing the damaging effects of chemotherapeutic agents (idarubicin and cyclophosphamide) on Chang liver cells, and may be useful in preventing the toxic effects of these agents in individuals undergoing cancer treatment.(38) Grape seed OPCs were also reported in a laboratory animal study to be hepatoprotective against acetaminophen, decreasing the damaging effects on hepatocytes and reducing liver injury.(39)
OPCs have been reported to inhibit the degredation of mast cells and the subsequent release of mediators of inflammation, such as histamine and prostaglandins, and therefore may be useful in allergies and sinus problems.(40),(41) OPCs have also been reported to inhibit the enzyme xanthine oxidase, a major producer of free radicals.(42) OPCs have been used in allergies because of their reported ability to inhibit degradation of mast cells and the subsequent release of histamine and other mediators of inflammation. In contrast, a study involving forty-nine seasonal allergic rhinitis sufferers compared the effects of 100mg grape seed extract twice a day against placebo. The evaluation of multiple endpoints demonstrated no significant differences between the treatment and placebo groups.(43)