The peel, arils, seeds and flowers of pomegranate was compared to the juice in relation to a range of factors associated with hardening of the arteries (atherosclerosis), and suggests that the heart health benefits be ubiquitous in all areas of the plant.
The study, by researchers from the Technion-Israel Institute of Technology and the University of Mississippi, is published on-line in the Journal of Agricultural and Food Chemistry.
The health-benefits of pomegranate have focussed almost exclusively on the pulp and juice of the fruit, most notably in fruit form although extracts are also gaining increasing attention.
The antioxidant-rich fruit have been linked to improved heart health, and claims that it may offer protection against prostate cancer, Alzheimer's, and may slow cartilage loss in arthritis.
It is these antioxidants, and particularly compounds like punicalagin, which accounts for about half of the fruit's antioxidant ability, that are reportedly behind the proposed health benefits.
Interestingly, other parts of the plant have also been receiving attention, with recent reports suggesting that, for example, extracts from the leaves of the pomegranate may be a novel appetite suppressant ( International Journal of Obesity , doi: 10.1038/sj.ijo.0803502), and that the peel may offer higher yields of phenolics, flavonoids and proanythocyanidins than the pulp ( Food Chemistry , Vol. 96, pp. 254-260).
The new study, led by Michael Aviram, looked at the effects of the extracts in laboratory mice engineered to be susceptible to atherosclerosis.
The mice consumed the pomegranate extracts (200 micrograms of gallic acid equivalents (GAE) per mouse per day) for three months.
Aviram and co-workers report that extracts from the flowers reduced the area of atherosclerotic lesions by 70 per cent, followed by the juice (40 per cent), and peel (39 per cent), compared to placebo.
Moreover, the flower extracts were associated with decreases in blood lipid and glucose levels of between 18 and 25 per cent.
The researchers also reported that the pomegranate extracts reduced the uptake of oxidised-LDL cholesterol, but only in the animals receiving the juice and peel.
"We conclude that attenuation of atherosclerosis development by some of the pomegranate extracts and, in particular, pomegranate flowers, could be related to the combined beneficial effects on serum lipids levels and on macrophage atherogenic properties," wrote Aviram.
The results, if translatable to humans, could offer an alternative source of pomegranate polyphenols for industry. Atherosclerosis, or hardening of the arteries, is a major risk factor for cardiovascular disease (CVD), which causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy about €169bn ($202bn) per year.
Atherosclerosis occurs naturally in humans as part of the aging process, but certain factors including high blood cholesterol, smoking, high blood pressure, obesity and diabetes increase the risk.
Source: Journal of Agricultural and Food Chemistry Published on-line ahead of print, ASAP Article, doi: 10.1021/jf071811q
"Pomegranate Phenolics from the Peels, Arils, and Flowers Are Antiatherogenic: Studies in Vivo in Atherosclerotic Apolipoprotein E-Deficient (E0) Mice and in Vitro in Cultured Macrophages and Lipoproteins" Authors: M. Aviram, N. Volkova, R. Coleman, M. Dreher, M. Kesava Reddy, D. Ferreira, M. Rosenblat