The leaves and fruit of the grape have been used medicinally since ancient Greece. Today, grape seed extract is used as a folk or traditional remedy for conditions related to the heart and blood vessels, such as atherosclerosis (hardening of the arteries), high blood pressure, high cholesterol, and poor circulation; complications related to diabetes, such as nerve and eye damage; vision problems, such as macular degeneration (which can cause blindness); swelling after an injury or surgery; cancer prevention; and wound healing.
The grape seeds used to produce grape seed extract are generally obtained from wine manufacturers. Grape seed extract is available in capsule and tablet forms.
What the science says
Studies have found that some compounds in 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). Larger trials are needed to confirm these findings.
Grape seed extract contains antioxidants, which help prevent cell damage caused by free radicals (highly reactive molecules that can damage cell function). Preliminary studies have shown some beneficial antioxidant effects; however, more research is needed.
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.
NCI is also funding studies to evaluate whether grape seed extract is effective in preventing breast cancer in postmenopausal women and prostate cancer.
NCCIH 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. Another study is investigating the effects of grape seed extract on colon cancer.
Side effects and cautions
Grape seed extract is generally well tolerated when taken by mouth. It has been used safely for up to 8 weeks in clinical trials.
Side effects that have been reported include a dry, itchy scalp; dizziness; headache; high blood pressure; hives; indigestion; and nausea.
Interactions between grape seed extract and medicines or other supplements have not been carefully studied.
Tell all your health care providers about any complementary health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.
Source: Herbs at a Glance. https://nccih.nih.gov/health/grapeseed/ataglance.htm.