Grapes (Vitis vinifera), especially red grapes, are a very good source of resveratrol and anthocyanins such as delphinidin. Red grapes are also good sources of fisetin and incorporate some lupeol, myricetin, oleanolic acid, and the resveratrol derivative pterostilbene. Each of these compounds have chemopreventive properties.
Muscadine grapes, in particular the skins and seeds, are a very good source of ellagic acid. Green or white grapes have less powerful anticancer properties than red grapes since they incorporate fewer chemopreventive compounds. Raisins are made by dehydrating grapes and can be a good source of micronutrients such as oleanolic acid that are concentrated in grape skin. Note that grape seed oil and grape seed extract are covered in another webpage.

Breast cancer-related effects of eating grapes

Grape consumption is associated with reduced breast cancer risk. Grape extracts and compounds have been found to promote apoptosis (programmed cell death), suppress cell cycle progression and inhibit both angiogenesis (the formation of new blood vessels) and aromatase (the synthesis of estrogen from androgens within the body). Grapes can also increase the beneficial effects of certain breast cancer treatments, including radiotherapy, aromatase inhibitors, Adriamycin (doxorubicin), Taxol (paclitaxel), and Herceptin (trastuzumab). One 2020 study reported that a dietary grape polyphenol concentrate reduced the cardiomyopathy induced by Adriamycin in a mouse model of chemotherapy.

Epidemiological studies

Several population studies have reported that grape consumption is associated with reduced risk of breast cancer. One large prospective study reported that adolescents with high grape intake had reduced risk of breast cancer in adulthood.

Grape anthocyanins

Grape anthocyanins, including delphinidin, malvidin, peonidin and petunidin, are closely-related plant pigments that give red and dark grapes their rich color. Women in the highest quartile (fourth) of anthocyanin intake had significantly lower risk of breast cancer than those in the lowest quartile of consumption in one study. Anthocyanins have also been shown to reduce Adriamycin chemotherapy-induced heart damage.
Delphinidin is found in red grapes, but is especially abundant in dark varieties such as Concord and Moon Drop grapes. Delphinidin has been demonstrated to inhibit the carcinogen-induced transformation of normal cells into breast cancer cells. Delphinidin has also been shown to block epidermal growth factor receptor (EGFR) signaling in breast cancer cells. EGFR, which is expressed at high levels in at least 30% of breast cancers, is associated with a poor prognosis.
In addition, delphinidin has been reported to suppress the growth of hormone receptor positive (ER+/PR+), HER2+, and triple negative (ER-/PR-/HER2-) breast cancer cells. Delphinidin has also been found to inhibit angiogenesis and migration of triple negative breast cancer cells and to reduce tumor growth in a mouse model of triple negative breast cancer.
High dietary intake of malvidin and peonidin have both been reported to be associated with reduced levels of systemic inflammation, a breast cancer risk factor. Malvidin has also been shown to reduce the growth and proliferation of ER+/PR+ breast cancer cells. Peonidin has been reported to suppress angiogenesis by inhibiting proliferation and migration.
Peonidin has also been found to induce apoptosis in HER2+ breast cancer cells and to reduce tumor size and volume in an animal model of HER2+ breast cancer. In addition, peonidin has been shown to increase the treatment effects of Herceptin in HER2+ cells.
Petunidin has been demonstrated to reduce growth and proliferation of ER+/PR+ breast cancer cells.

Resveratrol

Dark and red grape varieties are dietary sources of resveratrol, which has been reported to suppress proliferation of breast cancer cells and promote cancer cell death. Resveratrol has also been shown to increase the cytotoxic effects of radiotherapy and the chemotherapy drugs Adriamycin and Taxol against breast cancer. Resveratrol has also been found to potentiate tamoxifen treatment and to inhibit aromatase (the synthesis of estrogen from androgens within the body), thereby strengthening the treatment effects of aromatase inhibitors.
Resveratrol has also been reported to inhibit lung metastasis in a mouse model of triple negative breast cancer. In addition, resveratrol has been demonstrated to help protect against cisplatin-induced ovarian and uterine damage.

Muscadine grapes

Muscadine grapes (Vitis rotundifolia), also known as scuppernong grapes, are a species of grape native to the Southern United States. These grapes can be eaten fresh but have tough skins and are more often used to make wine, juice, pies and jelly. They are a richer source of polyphenols than regular table grapes, containing more ellagic acid, among other phytonutrients.
Muscadine grape polyphenols have been shown to reduce the growth and proliferation of both triple negative and HER2+ breast cancer cells. One study found that a muscadine grape extract diet reduced metastatic progression in a mouse model of triple negative breast cancer. Another study reported that muscadine grape extract significantly reduced tumor volume and number in mice prone to developing HER2+ mammary tumors. Still another study demonstrated that muscadine grape reduced the cardiotoxicity of Herceptin in a mouse model of HER2+ breast cancer.
The muscadine grape compound ellagic acid has been shown to reduce proliferation of ER+/PR+ breast cancer cells. Ellagic acid has also been found to be effective in the prevention of estrogen-induced mammary tumors in rats. In fact, ellagic acid has been shown to inhibit breast cancer development in a variety of cell and animal studies, in part by inhibiting angiogenesis.

Additional comments

Non-organic grapes (especially imported) must be washed very thoroughly to remove pesticide residue.

Sources of information provided in this webpage

The information above, which is updated continually as new research becomes available, has been developed based solely on the results of academic studies. Clicking on any of the underlined terms will take you to its tag or webpage, which contain more extensive information.
Below are links to 20 recent studies concerning this food and its components. For a more complete list, including less recent studies, please click on grapes.