Grape seed extract is used for conditions related to the heart and blood vessels, such as atherosclerosis (hardening of the arteries), high blood pressure, high cholesterol, and poor circulation.
Other reasons for the use of grape seed extract include complications related to diabetes, such as nerve and eye damage; vision problems, such as macular degeneration (which can cause blindness); and swelling after an injury or surgery.
Grape seed extract is also used for cancer prevention and wound healing.
Studies have found that some compounds of grape seed extract may be effective in relieving symptoms of chronic venous insufficiency (when veins have problems sending blood from the legs back to the heart) and reducing edema (swelling) after an injury or surgery.
Small randomized trials have found beneficial effects of grape seed extract for diabetic retinopathy (an eye problem caused by diabetes) and for vascular fragility (weakness in small blood vessels).
Grape seed extract contains antioxidants, which help prevent cell damage caused by free radicals (highly reactive molecules that can damage cell function).
A study funded by the National Cancer Institute (NCI) found that grape seed extract did not reduce the hardening of breast tissue that can occur after radiation therapy for breast cancer.
NCCAM is studying whether the action of grape seed extract and its components may benefit the heart or help prevent cognitive decline, Alzheimer's disease, and other brain disorders.