Proanthocyanidins (PACs) are polymer chains of flavonoids. They are also known as oligomeric proanthocyanidins (OPCs), leukocyanidins, and condensed tannins. These compounds are found in plants, such as apples, grape seeds, and cinnamon. They are also found in black and green teas, as well as red and white wine, though in substantially lower levels than their parent plants.
The first of these flavonoids were isolated in 1936 by Professor Jacques Masquelier, and given the name vitamin P. This name was never officially recognized and is no longer used. Masquelier was responsible for creating the techniques by which proanthocyanidins could be extracted from plants. These extracts have been used in Europe as a supplement for nutritional and therapeutic use for over 25 years, but the United States has only recently begun to see an increase in their use.
One of the most popular uses is as antioxidants, which means that they slow or inhibit the oxidization of other molecules. When a molecule oxidizes, there is a possibility that a free radical will be produced. A free radical is an atom, molecule, or ion that carries an unpaired electron. This causes them to be highly chemically reactive, and they will bond easily with many compounds essential for cellular growth and maintenance. When this happens, there is a chance that the free radical will start a chain reaction, resulting in cellular damage. Proanthocyanidins are thought to be free radical scavengers, which means that they readily bond with free radicals, thereby limiting their interactions with healthy cells.
Proanthocyanidin supplements are also used to combat heart disease. Studies have demonstrated that proanthocyanidins are able to reduce blood pressure and increase fat metabolism. Clinical tests, using rabbits that were given grapeseed oil, have shown that PACs are able to reduce the development of aortic atherosclerosis. In addition, there is some evidence to suggest that the supplements may counter the effects of high cholesterol on the heart and surrounding blood vessels.
These compounds also aid in the stabilization of collagen and elastin proteins in the body, which are required for healthy and resilient skin. Both of these proteins are also integral to the structure of of blood vessels and muscle fibers. In several double-blind trials, proanthocyanidin supplements produced a measurable increase in capillary strength. A French study, in which women with chronic venous insufficiency were given 150 milligram (mg) doses of proanthocyanidins daily, showed an decrease in all symptoms related to the condition. There are no noted side effects associated with the use of this compound, even in high doses.