Grape seed extract is very rich in oligomeric proanthocyanidin complexes, which can aid in nerve damage, atherosclerosis, macular degeneration. Grape seed extract is available as a liquid supplement, or as tablets or capsules, generally in doses of 50 to 100 milligrams. Other potential benefits of grape seed extract include relieving chronic venous insufficiency, and helping with high cholesterol as well as eye conditions related to diabetes.