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Grape Seed Extracts Show Promise Against Leukemia, Obesity

Two studies find red-wine compounds perform powerful tasks; debate rages over whether supplements or wine offer best results

Jacob Gaffney
Posted: January 14, 2009

The chemicals swirling around in that glass of red wine may pack more of a punch than the alcohol alone provides. Two recent American studies find that extracts from grape seeds can kill both leukemia cells and fat cells in a controlled laboratory environment. But scientists are unsure whether wine, grape seed extracts or supplements offer the best medicine.

The leukemia study, published in the January issue of Clinical Cancer Research, focused on anthocyanidins, a class of compounds that lend grapes their color and are part of vines' natural defenses. Previous research has found that anthocyanidins selectively eradicate leukemia cells. But the latest research from the University of Kentucky uncovered a mechanism that may explain why anthocyanidin-rich grape seed extract could be an effective cancer cell killer. According to the study, the extract activates proteins inside of cancer cells that are responsible for regulating the cells' life cycle.

The researchers exposed leukemia cells in cultures to various doses of a commercially available grape seed extract. After being exposed to the most effective dosage for 24 hours, 76 percent of the leukemia cells self-destructed in a form of programmed cell death known as apoptosis. The cause of apoptosis was the activation of a protein, called JNK.

"These results could have implications for the incorporation of agents such as grape seed extract into prevention or treatment of hematological malignancies and possibly other cancers," said the study's lead author, Xianglin Shi, a professor at the Graduate Center for Toxicology at Kentucky, in a statement. However, Shi warns that it is unclear if ingesting grapes or wine could provide a similar result, and added that apple skins also contain relatively high levels of anthocyanidins. "This is very promising research," he said. "But it is too early to say this is chemo-protective."

The study on human fat cell lines, published in the December issue of the Journal of Medicinal Food, used a combination of three plant-based chemicals as a potential weapon against obesity: genistein, which abounds in soybeans, and quercetin and resveratrol, both of which are found in red wine. All three belong to a class of chemicals called flavonoids and are believed to act as powerful antioxidants.

The study was conducted by the departments of Foods and Nutrition and Animal & Dairy Science at the University of Georgia, under the sponsorship of Aptotec, a commercial obesity research center. Scientists found that a combination of genistein, quercetin and resveratrol induced death in human fat cell lines at low concentrations.

The effect was greater than experiments employing resveratrol alone, even when extremely high doses of resveratrol were used. This is notable, the study authors write, considering previous studies into resveratrol's effects on overweight mice used levels of the compound that are unobtainable though the regular consumption of resveratrol-rich food and drink.

Critics have argued that these resveratrol-focused studies may be skewed to benefit certain resveratrol supplement manufacturers who were involved in the research. (However, one of the co-authors of the Georgia study, University of Georgia researcher Clifton Baile, is also CEO of Aptotec, which would presumably profit from any obesity treatment.)

"I think most nutritionists recommend eating a wide variety of fruits and vegetables in order to have adequate amounts of vitamins and minerals," said University of Georgia research scientist MaryAnne Della-Fera, who is also the chief scientific officer of Aptotec. "However, it may be equally important in providing a wider exposure to and flavonoids and other compounds that help keep us healthy."

Della-Fera added that while resveratrol, for example, appears to have important effects by itself at high doses, their research goal remains to identify combinations that would induce the same effect but require much lower amounts of each individual compound. "In that way, the low levels that get absorbed into the blood are much more likely to produce a beneficial effect and also less likely to cause adverse effects," she said.

However, Della-Fera argued that some perspective is needed when considering the larger picture behind studies such as these. "If someone enjoys having an occasional glass of wine, there's no real need to call it a 'medicinal food,' just an enjoyable food," she said. "Moderate consumption of wine, particularly red wine, is thought to have beneficial health effects, possibly due to the presence of grape polyphenols such as resveratrol, but no one really knows what the basis of this health effect is."

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