Grapes (Vitis vinifera) have been heralded for their medicinal and nutritional value for thousands of years. Egyptians ate grapes at least 6,000 years ago, and several ancient Greek philosophers praised the healing power of grapes -- usually in the form of wine. European folk healers made an ointment from the sap of grapevines to treat skin and eye diseases. Grape leaves were used to stop bleeding, inflammation, and pain, such as the kind brought on by hemorrhoids. Unripe grapes were used to treat sore throats and dried grapes (raisins) were used for constipation and thirst. Round, ripe, sweet grapes were used to treat a range of health problems including cancer, cholera, smallpox, nausea, eye infections, and skin, kidney, and liver diseases.
But grapes -- or the chemicals within them, especially oligomeric proanthocyanidin complexes (OPCs) -- have been touted as powerful antioxidants. Some people believe they could help treat a number of conditions, from heart disease to cancer to aging skin, although scientific evidence is mostly lacking for those conditions. However, there is good evidence that grape seed extract can help treat chronic venous insufficiency and edema.
A study of healthy volunteers found that taking grape seed extract did substantially increase levels of antioxidants in their blood. Antioxidants are substances that destroy free radicals -- harmful compounds in the body that damage DNA (genetic material) and even cause cell death. Free radicals are believed to contribute to aging as well as the development of a number of health problems, including heart disease and cancer.
Today, standardized extracts of grape seed may be used to treat a range of health problems related to free radical damage, including heart disease, diabetes, and cancer. Some studies -- mostly in animals -- support these uses.
Flavonoids found in red wine may help to protect the heart by lowering "bad" LDL cholesterol. The so-called "French paradox" is the belief that drinking wine protects people living in France from developing heart disease at the high rates seen in people living in the United States. So far, however, there is no clear evidence that taking grape seed extract helps reduce heart disease. Some researchers speculate that it may the alcohol in the wine, and not the flavonoids, that could be responsible for any healthful effects. Others think it could be the combination of alcohol and flavonoids.
Drinking alcohol to protect against heart disease is not advocated by the American Heart Association and other organizations because of the potential for addiction and other serious problems, such as car accidents and the increased risk of hypertension, liver disease, breast cancer, and weight gain. If you do drink red wine, you should have no more than 2 glasses (20 g ethanol) per day if you are a man, and no more than one if you are a woman.
Chronic venous insufficiency
In chronic venous insufficiency, blood pools in the legs, causing pain, swelling, fatigue, and visible veins. A number of high-quality studies have shown that OPCs from grape seed can reduce symptoms.
Edema
Edema -- swelling caused by surgery or an injury -- seems to go away faster when people take grape seed extract. Edema is common after breast cancer surgery, and one double-blind, placebo-controlled study found that breast cancer patients who took 600 mg of grape seed extract daily after surgery for six months had less edema and pain than those who took placebo. Another study found that people who took grape seed extract after experiencing a sports injury had less swelling than those who took placebo.
High cholesterol
There isn't enough evidence to say whether taking grape seed extract can lower cholesterol, although two preliminary studies showed promising results. A study of 40 people with high cholesterol looked at whether taking grape seed extract, chromium, a combination of both, or placebo for 2 months would lower cholesterol. The combination of grape seed extract and chromium was more effective than either grape seed alone or placebo in lowering total and LDL ("bad") cholesterol.
Another study looked at the effects of a proprietary grape seed extract on lipid peroxidation (the breakdown of fats in the blood) in a group of heavy smokers. Twenty-four healthy male smokers, (aged 50 years or greater) took either placebo or 2 capsules (75 mg of a grape procyanidin extracts and soy-phosphatidalcholine), twice daily for 4 weeks. "Bad" LDL cholesterol levels were lower in those taking the grape seed supplement than those taking placebo.
High blood pressure
Theoretically, grape seed extract might help treat hypertension or high blood pressure. Antioxidants, like the ones found in grape seed, help protect blood vessels from damage. Damaged blood vessels can lead to higher blood pressure. In several animal studies, a grape seed extract substantially reduced blood pressure. But human studies are needed to see whether grape seed extract helps people with high blood pressure.
Cancer
Studies have found that grape seed extracts may prevent the growth of breast, stomach, colon, prostate, and lung cancer cells in test tubes. However, there is no clear evidence yet whether it works in humans. Antioxidants, such as those found in grape seed extract, are thought to reduce the risk of developing cancer. Grape seed extract may also help prevent damage to human liver cells caused by chemotherapy medications. Talk to your doctor or pharmacist before combining antioxidants with any chemotherapy drugs to make sure they interact safely together.
Other conditions
Grape seed extract is sometimes suggested for the following, although evidence is slight:
- Diabetes (improving blood sugar control)
- Improving night vision
- Protecting collagen and elastin in skin (anti-aging)
- Treating hemorrhoids
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