The juice of pomegranate is more effective than apple in boosting the body's antioxidant defences, which decline naturally with age, reports a new study.
The antioxidant capacity of the blood of 26 elderly subjects increased by almost 10 per cent after drinking pomegranate juice, whereas changes were negligible after apple juice, report the researchers from the Institute of Hygiene and Environmental Medicine in Tianjin, China.
The study, published in this month's issue of Nutrition Research, is sure to be welcomed by producers of pomegranate products, already benefiting from a wealth of science reporting potential benefits of the fruit, ranging from protection against prostate cancer, slowing cartilage loss in arthritis, and potentially preventing Alzheimer's.
Pomegranate, known as the royal fruit because of the 'crown' on top, is a rich source of antioxidants. It is these antioxidants, and particularly ellagitannin compounds like punicalagins and punicalins, which accounts for about half of the fruit's antioxidant ability, that are reportedly behind the proposed health benefits.
Indeed, it is these compounds which most likely account for boosting the antioxidant capacity of the elderly subjects in the new study, wrote the authors.
"Because the plasma ascorbic acid, vitamin E, and reduced glutathione contents did not differ significantly between the two groups in this study, the phenolics may be the functional components contained in pomegranate juice that accounted for the observations," wrote lead author Changjiang Guo.
The subjects (average age 63.5) were randomly divided into two groups and assigned to drink 250 ml daily of either apple (Great Lake Co., China) or pomegranate juice (freshly made from pomegranate pulps from Shandong Red Pomegranate Co., China) for four weeks.
At the end of the study Guo and co-workers report that the plasma antioxidant capacity of the subjects consuming pomegranate juice had increased from 1.33 to 1.46 millimoles per litre (mmol/l), using the FRAP assay of antioxidant quantification. On the other hand, the antioxidant capacity of the subjects consuming apple juice changed negligibly from 1.37 to 1.36 mmol/l.
Furthermore, urine levels of 8-hydroxydeoxyguanosine (8-OH-dG), the product of hydroxyl radical attack - reportedly a marker of damaged DNA - was reduced by about 21 per cent in the pomegranate group than in the apple group, report the researchers. However, they failed to detect significant changes in cellular DNA damage. Guo and co-workers failed to explain this discrepancy.
DNA damage from oxidative stress has been linked to an increased risk of various diseases, particularly cancer.
"Because there was limited subject participation in this short-term intervention, a large-scale and long-term study is warranted to confirm the results obtained in this study," concluded the researchers.
At the SupplySide West International Trade Show and Conference in Las Vegas in November 2007, Navindra Seeram from the University of California, Los Angeles (UCLA) hailed the fruit as the shining light for how to capitalise on consumers' growing interest in exotic fruits and ensure they offer benefits and not empty hype.
Source: Nutrition Research (Elsevier)
February 2008, Volume 28, Issue 2, Pages 72-77
"Pomegranate juice is potentially better than apple juice in improving antioxidant function in elderly subjects"
Authors: C. Guo, J. Wei, J. Yang, J. Xu, W. Pang, Y. Jiang