Grape seed extract is a flavonoid, a plant substance with antioxidant properties that protect cells from damage by free radicals (unstable oxygen molecules). As its name suggests, the extract is made from the seeds, and sometimes the skins, of red grapes.
Some laboratory tests suggest that active ingredients in grape seed extract, called procyanidolic oligomers (PCOs) or proanthocyanidins, have 50 times greater antioxidant activity than Vitamin C or E. PCOs may also improve blood circulation and help strengthen blood vessels, and may help reduce swelling after surgery or injury.
People with fibromyalgia may take grape seed extract because its antioxidant power may help protect muscle cells from damage.
(Source: Natural Treatments for Fibromyalgia: An A to Z Guide, by Kenna Simmons. An official publication of the Arthritis Foundation. To purchase, visit www.arthritis.org.)