Grapes contain polyphenols such as resveratrol and delphinidin that can act as antioxidants, antiangiogenics, and selective estrogen receptor modifiers. Grapes also contain lupeol, pterostilbene, oleanolic acid, myricetin, and fisetin. Each of these polyphenols have been found to have chemopreventative properties. Muscadine grapes also contain ellagic acid. Green or white grapes have less powerful anticancer properties than red grapes since they contain fewer polyphenols. Note that grape seed oil and grape seed extract are covered in another web page.
Breast cancer-related effects of eating grapes
Red grapes and grape seeds are a good source of resveratrol, which has the ability to suppress proliferation of breast cancer cells and promote cell death. Resveratrol also can inhibit aromatase (the synthesis of estrogen from androgens within the body), which is important for reducing growth-stimulatory effects in estrogen-dependent breast cancer. Resveratrol has also been shown to increase the effects of radiation treatment, aromatase inhibitors and the chemotherapy drugs Adriamycin (doxorubicin) and Taxol (paclitaxel) against breast cancer. Other grape polyphenols such as quercetin have also been shown to have chemopreventive effects and appear to act synergistically with resveratrol in inhibiting breast cancer growth.
Delphinidin, an anthocyanin found in red grapes, has 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.) Delphinidin was shown to induce apoptosis (programmed cell death) in HER2+ breast cancer cells in another study.
Muscadine grape polyphenols have been shown to reduce the growth and proliferation of both triple negative (ER-/PR-/HER2-) and HER2+ breast cancer ells. One 2015 study reported that consuming muscadine grape extract significantly reduced tumor volume and number in mice prone to developing HER2+ mammary tumors.
Several population studies have reported that grape consumption is associated with reduced risk of breast cancer. A large 2016 prospective study reported that adolescents with high grape intake had reduced risk of breast cancer in adulthood.
Muscadine grapes, which can be eaten fresh, but more often are used to make wine, juice, and jelly, are native to the southern and southeastern U.S. These grapes are richer sources of polyphenols than regular table grapes, containing more ellagic acid, among other phytonutrients.
Raisins are made by dehydrating grapes.
Non-organic (especially imported) grapes must be washed very thoroughly to remove pesticide residue.
Below are links to recent studies concerning this food. For a more complete list, including less recent studies, please click on grapes.