Muscadine grapes (Vitis rotundifolia) are a type of grape native to the southeastern United States. Unlike the more common red grapes which are used to make red wines well known for their content of the antioxidant resveratrol, muscadine grapes are different, and here’s why.
How Muscadine Grape Skin Extract Works
Muscadine grape skin extract is a supplement derived from the skin of the purple and red muscadine grapes. In a study from the University of Florida, researchers analyzed the seeds, skin, and pulp of eight cultivars of muscadine grapes and reported they found a total of 88 phenolic compounds, which include polyphenols. The skins contained 28 compounds, including tannins and flavonoids such as quercetin, myricetin, and kaempferol glycosides, all of which have antioxidant properties. (Sandhu 2010)
Muscadine grapes are a rich source of other phytochemicals called anthocyanins which, along with their ability to give the grapes their purple and red colors, have potent antioxidant and anti-inflammatory properties and have demonstrated anticancer effects as well. Muscadine grapes also reportedly have an extra pair of chromosomes, and this feature is believed to be a reason why muscadine grapes produce phytochemicals not found in other grapes, such as ellagic acid. Ellagic acid is believed to have a role in preventing cancer from developing, growing, and spreading.
Prostate Cancer and Muscadine Grape Skin Extract
Scientists from the National Cancer Institute and a research team evaluated muscadine grape skin extract and its activity against human prostate cancer cells. Using a series of different stages of prostate cancer, the investigators showed that muscadine grape skin extract significantly inhibited the growth of the cancer cells, mainly through apoptosis (cell suicide or programmed cell death). The extract did not, however, have any impact on the normal prostate cells.
This activity by muscadine grape skin extract is different from that of resveratrol found in red grapes, which appears to block the life cycle of cancer cells. According to the study’s lead investigator Jeffrey E. Green, MD, chief of the Transgenic Oncogenesis and Genomics Section of the National Cancer Institute’s Center for Cancer Research, their findings indicate that muscadine grape skin extract has anticancer activities in the lab that are different from those seen in resveratrol. He also noted that the grape skin extract may inhibit tumor development at very early stages. (Green 2007)
Men who undergo radiation therapy may want to consider muscadine grape skin extract. In a study reported at the 100th Annual Meeting of the American Association for Cancer Research in April 2009, Dr. Ronald Carsten reported on the results of studies showing the ability of muscadine grape skin powder to prevent cancer therapy radiation side effects in mice. Carsten demonstrated that mice treated with muscadine grape skin powder two days before undergoing radiation showed significantly improved protection against radiation than did mice not given the powder.
In an accompanying study, Carsten compared muscadine grape skin powder with pure resveratrol, which also provides protection against radiation treatment. He found that the grape skin powder was more potent than resveratrol and also offered protection against the development of leukemia, a side effect of radiation therapy in some cancer patients. Mice fed muscadine grape skin extract had protection against gene defects associated with development of leukemia. (Carsten 2009)
Other Benefits of Muscadine Grape Skin Extract
The antioxidant and antimicrobial properties of muscadine grape skins proved helpful in a study in which researchers tested the grape’s potential and its flavonoid, quercetin, against Helicobacter pylori infection, bacteria that cause peptic ulcers. Using mouse models, the scientists found that the grape skin and quercetin significantly reduced inflammatory substances and moderately reduced H. pylori levels in mice treated with muscadine grape skin and quercetin when compared with control mice. (Brown 2011)
A University of Georgia study highlighted the anti-inflammatory powers of muscadine grape skins. After drying, pulverizing, and extracting the grape skins, researchers tested the extract in two tests involving an inflammatory process—one using superoxide and the other using cytokines. In both experiments, the muscadine grape skin extract inhibited the release of these pro-inflammatory substances. Then the scientists tested the grape skin extract in rats that were injected with carrageenan, which causes inflammation. Rats that were given a grape skin diet had about 50 percent less inflammation than did rats not given the diet. (Greenspan 2005)
How To Take Muscadine Grape Skin Extract
Muscadine grape skin extract supplements are available in capsules and powder, which can be mixed into soft food or beverages. The suggested daily dose is 1,000 to 3,000 mg. Although no side effects have been reported, talk to your healthcare provider before using muscadine grape skin extract.
Brown JC et al. Activities of muscadine grape skin and quercetin against Helicobacter pylori infection in mice. J Appl Microbiol 2011 Jan; 110(1): 139-46
Carsten R. Muscadine grape skin dietary supplement protects against cancer therapy radiation side effects. 2009.
Greenspan P et al. Antiinflammatory properties of the muscadine grape (Vitis rotundifoia). J Agric Food Chem 2005 Nov 2; 53 (22): 8484-84
Hudson TS et al. Inhibition of prostate cancer growth by muscadine grape skin extract and resveratrol through distinct mechanisms. Cancer Res 2007; 67(17)
Sandhu AK, Gu L. Antioxidant capacity, phenolic content, and profiling of phenolic compounds in the seeds, skin, and pulp of Vitis rotundifolia (Muscadine Grapes) a determined by HPLC-DAD-ESI-MS(n). J Agric Food Chem 2010 Apr 28l 58(8): 4681-92