August 14, 2006
A recent collaborative study between Italian and U.S. researchers has shown that the flesh of grapes has similar protective effects as red grape skin. The results of the study were recently published in an online version of the Journal of Agricultural and Food Chemistry (see http://pubs.acs.org/cgi-bin/abstract.cgi/jafcau/asap/abs/jf061048k.html). Researchers from the Institute of Technological Development of Agricultural Products, Milan, Italy; the Enology Experimental Institute, Velletri, Italy; the National Council of Research, Institute of Molecular Science and Technology, Milan, Italy; and Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, contributed to this study.
After administering either grape skin extract, grape flesh extract or water (control) for 30 days, the researchers subjected the laboratory animals to a stimulus, similar to a heart attack, that then enabled a measurement of malondialdehyde (MDA), a compound associated with oxidative stress. The animals fed the grape skin extract or the grape flesh extract had a significantly lower response to the imposed stimulus compared to the control group. However, no apparent differences were seen between the two groups, leading researchers to posit that both the skin and flesh of grapes have similar effects on heart health.
Using high-performance liquid chromatography, the researchers revealed that skin and flesh contained comparable amounts of several active compounds, including tartaric acid and malic acid. However, despite the fact that the flesh had lower total polyphenolic levels and no anthocyanins, the researchers concluded that both the flesh and skin have comparable effects on heart health, noting that the free-radical-scavenging abilities of both substances were the same. "The results indicate for the first time that the flesh of grapes are equally cardioprotective as skin, and antioxidant potential of skin and flesh of grapes are comparable with each other despite of the fact that flesh does not possess any anthocyanin activities," note the authors in the published report. The researchers note that further study is required to determine the precise compounds in grape flesh responsible for their healthful effects.
This study helps round out the healthful benefits of grapes, since grape seeds have also demonstrated healthful qualities stemming from their resveratrol and proanthocyanidin content.
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