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Grapes

Other common name(s): grape diet, grape cure, grape seed extract (GSE), grape seed proanthocyanidin extract (GSPE), grape seed oil, grape skins, proanthocyanidins, oligomeric proanthocyanidins (OPCs), resveratrol

Scientific/medical name(s): Vitis vinifera, Vitis coignetiae

Description

Grapes grow wild on vines or are cultivated. They are believed to be native to northwest Asia although they have been grown throughout Europe and the United States for centuries. The seeds, skin, leaves, stems, and grape itself are used in herbal remedies. At times in the past, diets consisting solely of grapes have been touted as an alternative means of treating cancer. Some chemicals found in grape extract (called proanthocyanidins) and in grape skins (called resveratrol) are currently being studied for possible uses in the prevention and treatment of cancer and other illnesses.

Overview

Available scientific evidence does not support claims that a diet of grapes alone is effective for treating cancer or any other disease. Some laboratory evidence suggests that certain chemicals in grapes and their seeds and skins may help prevent heart disease and cancer, but more research is needed in people to understand the possible long-term benefits.

How is it promoted for use?

Alternative practitioners recommend the use of grapes and parts of the grape plant for high blood pressure, menopause, varicose veins, high cholesterol, skin rashes, and urination problems. They also claim it works for inflammation of the gums, throat, eyes, and mouth. Although used rarely today, the grape diet (see below) was promoted at different times in the twentieth century as a treatment to flush toxins from the body and protect the body against cancer and virtually all other diseases. Some supporters believed that the diet cured cancer.

Evidence suggests that proanthocyanidins,the chemical found in grape seed extract are powerful antioxidants. Antioxidants are compounds that block the action of free radicals, activated oxygen molecules that can damage cells. Proponents claim that these antioxidants inhibit the development of some types of cancer, protect against heart disease, and are useful for treating a variety of medical conditions such as arthritis, allergies, circulatory problems, diabetes, water retention, and vision problems.

A compound called resveratrol, which is found in the skins of red grapes is being studied to see how it affects the development and progression of heart disease and cancer.

What does it involve?

Fresh, preserved, and dried grapes are used as is or in the form of liquid extracts, tinctures, gargles, enemas, douches, and compresses. Grape skins are also used in making red wine. Grape seed extract and resveratrol are available as dietary supplements in tablet and capsule form. The amount of these substances in different supplements varies by manufacturer.

The complete grape diet begins with fasting and daily enemas for a few days and is followed by a diet of grapes and water for one to 2 weeks. Then, fresh fruits and sour milk can also be consumed. The next stage of the diet includes raw vegetables, salads, nuts, dairy products, honey, and olive oil. During the final stage of the diet, if a person is doing well, he or she may be allowed to add one cooked meal per day.

What is the history behind it?

Grapes have been associated with health for many centuries. Evidence of fossilized grape leaves, stems, and seeds dating back 10 to 12 million years ago has been found in the Northern hemisphere. Grapes from the Vitis vinifera species were grown for thousands of years in the Old World before they were brought to the United States.

Johanna Brandt, a South African dietitian, proposed the grape diet in 1925. Brandt claimed to have cured herself of stomach cancer by following the diet. After immigrating to the United States in 1927, she opened the Harmony Healing Centre in New York City and began promoting the treatment. She wrote a book that was first published in 1928 and was republished several times throughout the 20th century. Because no scientific evidence supported their claims that the treatment improved health or cured disease, Brandt and some of her followers who prescribed or promoted the grape diet as a cure for cancer eventually became the targets of intense criticism and even legal action.

During the past few decades, interest in understanding the role of antioxidants in health has begun to grow. Proanthocyanidins were extracted from grape seeds in 1970. In the mid-1990s, a compound called resveratrol, found mostly in the skins of red grapes, was first suggested to be responsible for the "French paradox," the low occurrence of heart disease among the French, who tend to eat a high-fat diet.

What is the evidence?

While some substances in grapes may hold promise against cancer, there is very little reliable scientific evidence available at this time that drinking red wine, eating grapes, or following the grape diet can prevent or treat cancer in people.

Several laboratory studies in cell cultures have shown that proanthocyanidins, the chemicals found in grape seed extract, have antioxidant properties. A small randomized clinical trial of grape seed extract in healthy volunteers supported this finding. Some laboratory studies have also found that proanthocyanidins may reduce the body’s production of estrogen, which could possibly affect hormone-sensitive tumors such as some types of breast cancer. It is not yet clear whether these properties will translate into anticancer benefits in people. Early clinical trials are currently in progress to find the best dose of grape seed extract for suppressing estrogen levels for breast cancer prevention.

Studies in laboratory animals have suggested that grape seed extract may act against prostate, colon, and breast cancer. One laboratory study found that grape seed extract seemed to make the chemotherapy drug doxorubicin more effective against breast cancer cells. Randomized clinical trials are needed to determine whether grape seed extract can be helpful in cancer treatment.

Laboratory and animal studies have shown that resveratrol may help prevent heart disease and cancer. It appears to have antioxidant, anti-inflammatory, and possibly antiestrogenic properties. It also seems to activate liver enzymes that are responsible for ridding the body of unwanted chemicals. These properties may mean it will be active against cancer in people, but randomized clinical trials are needed to confirm this. Early clinical trials are now under way in healthy volunteers to determine the amount of resveratrol that can be given safely. This dose will then be used in studies of resveratrol for cancer prevention. Note, however, that a study of extracted chemicals would not be expected to have the same result as a study using the raw plant.

Some population-based studies have found that people who drink red wine may have lower incidences of lung and prostate cancer. As always in these types of studies, many other factors could account for the difference in cancer risk. In addition, several studies have found that high intake of alcohol, regardless of the type, is linked to an increase in breast cancer and some other types of cancer.

While the early research on some substances in grapes is promising, it is very hard to determine the exact role a particular food may have against cancer. A balanced diet that includes 5 or more servings a day of fruits and vegetables along with foods from a variety of other plant sources such as nuts, seeds, whole grain cereals, and beans is likely to be more effective than eating one particular food in large amounts.

Are there any possible problems or complications?

This product is sold as a dietary supplement in the United States. Unlike drugs (which must be tested before being allowed to be sold), the companies that make supplements are not required to prove to the Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is written on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

An exclusive grape diet is unhealthy and does not supply the body with adequate amounts of protein and important nutrients. Grape seed extract is believed to be safe, but additional research is needed for confirmation.

The amount of resveratrol in red wine varies greatly, and increased consumption of wine to raise resveratrol intake may pose certain health risks. Alcohol is linked with a higher risk of cancer of the mouth, esophagus, pharynx, larynx, and liver in both men and women, and a higher risk of breast cancer in women. Cancer risk also increases with the amount of alcohol consumed. However, the cardiovascular benefits of moderate drinking (2 drinks a day for men, 1 drink a day for women) may outweigh the risk of cancer in men over age 50 and in women over age 60.

Some substances in grapes may affect how quickly enzymes in the body get rid of certain chemicals, which could possibly affect the blood levels of certain drugs. If you are thinking about taking a grape-derived supplement, talk to your doctor.

The possible effects on pregnancy or breast-feeding have not been well studied. Relying on this treatment alone and avoiding or delaying conventional medical care for cancer, may have serious health consequences.

Additional resources

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-ACS-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer

References

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Athar M, Back JH, Tang X, Kim KH, Kopelovich L, Bickers DR, Kim AL. Resveratrol: a review of preclinical studies for human cancer prevention. Toxicol Appl Pharmacol. 2007;224:274-283.

Barrett S. The Grape Cure. 2001. Accessed at: http://www.quackwatch.org/01QuackeryRelatedTopics/Cancer/grape.html on June 10, 2008.

Eng ET, Ye J, Williams D, Phung S, Moore RE, Young MK, et al. Suppression of estrogen biosynthesis by procyanidin dimers in red wine and grape seeds. Cancer Res. 2003;63: 8516-8522.

Kaur M, Singh RP, Gu M, Agarwal R, Agarwal C. Grape seed extract inhibits in vitro and in vivo growth of human colorectal carcinoma cells. Clinical Cancer Research. 2006; 12:6194-202.

Kijima I, Phung S, Hur G, Kwok SL, Chen S. Grape seed extract is an aromatase inhibitor and a suppressor of aromatase expression. Cancer Research. 2006;66:5960-5967.

Kim H, Hall P, Smith M, Kirk M, Prasain JK, Barnes S, Grubbs C. Chemoprevention by grape seed extract and genistein in carcinogen-induced mammary cancer in rats is diet dependent. J Nutr. 2004;134:3445S-3452S.

Kushi LH, Byers T, Doyle C, Bandera EV, McCullough M, McTiernan A, Gansler T, Andrews KS, Thun MJ, American Cancer Society 2006 Nutrition and Physical Activity Guidelines Advisory Committee. American Cancer Society guidelines on Nutrition and Physical Activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity. CA Cancer J Clin 2006;56:254-281.

Memorial Sloan-Kettering Cancer Center. About herbs: Grape seed. 2006. Accessed at: http://www.mskcc.org/mskcc/html/69243.cfm on June 10, 2008.

Mitchell SH, Zhu W, Young CY. Resveratrol inhibits the expression and function of the androgen receptor in LNCaP prostate cancer cells. Cancer Res. 1999;59:5892-5895.

Mantena SK, Baliga MS, Katiyar SK. Grape seed proanthocyanidins induce apoptosis and inhibit metastasis of highly metastatic breast carcinoma cells. Carcinogenesis. 2006;27:1682-1691.

Mohan J, Gandhi AA, Bhavya BC, et al. Caspase-2 triggers Bax-Bak-dependent and -independent cell death in colon cancer cells treated with resveratrol. Journal of Biological Chemistry.2006; 281:17599-17611.

Moss RW. Herbs Against Cancer. New York, NY: Equinox Press; 1998.

National Institutes for Health. IH636 Grape Seed Extract in Preventing Breast Cancer in Postmenopausal Women at Risk of Developing Breast Cancer. Accessed at: http://clinicaltrials.gov/show/NCT00100893 on June 10, 2008.

Nuttall SL, Kendall MJ, Bombardelli E, Morazzoni P. An evaluation of the antioxidant activity of a standardized grape seed extract, Leucoselect. J Clin Pharm Ther. 1998;23:385-389.

PDRhealth. Grape seed proanthocyanidins. Accessed at: www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/gra_0129.shtml on June 10, 2008.

PDRhealth. Resveratrol. Accessed at:

www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/res_0224.shtml on June 10, 2008.

Ruano-Ravina A, Figueiras A, Barros-Dios JM. Type of wine and risk of lung cancer: A case-control study in Spain. Thorax. 2004;59:981-985.

Sharma G, Tyagi AK, Singh RP, Chan DC, Agarwal R. Synergistic anti-cancer effects of grape seed extract and conventional cytotoxic agent doxorubicin against human breast carcinoma cells. Breast Cancer Res Treat. 2004;85:1-12.

Veluri R, Singh RP, Liu Z, Thompson JA, Agarwal R, Agarwal C. Fractionation of grape seed extract and identification of gallic acid as one of the major active constituents causing growth inhibition and apoptotic death of DU145 human prostate carcinoma cells. Carcinogenesis. 2006; 27:1445-1453.

Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.


Last Medical Review: 11/01/2008
Last Revised: 11/01/2008