Pomegranate juice shows possible diabetes benefits
health benefits for diabetics, despite the juice containing
significant sugar concentrations.
The findings, although only from a small trial in humans, are likely to encourage further consumption of pomegranate juice in the UK, where sales have rocketed in the last year thanks to media coverage of the antioxidant-rich fruit that has commonly been linked to improved heart health, as well as claims that pomegranate could protect against prostate cancer and slows cartilage loss in arthritis.
One surprising finding, said lead researcher Professor Michael Aviram of from the Rappaport Family Institute for Research in the Medical Sciences and Rambam Medical Center, Haifa, Israel, was that the sugars contained in pomegranate juice - although similar in content to those found in other fruit juices - did not worsen diabetes disease parameters (including blood sugar levels) in patients, but in fact cut the risk of atherosclerosis.
"In most juices, sugars are present in free - and harmful - forms," explained Aviram. "In pomegranate juice, however, the sugars are attached to unique antioxidants, which actually make these sugars protective against atherosclerosis."
According to British charity, Diabetes UK, constantly raised glucose levels intensify the furring and hardening of blood vessels (atherosclerosis), which leads to cardiovascular disease and stroke.
An estimated 19 million people are affected by diabetes in the EU 25, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030.
In the US, there are over 20 million people with diabetes, equal to seven per cent of the population. The total costs are thought to be as much as $132 billion, with $92 billion being direct costs from medication, according to 2002 American Diabetes Association figures.
The new research, published in the August issue of the journal Atherosclerosis (Vol. 187, pp. 363-371), reports that subjects who drank 50 ml of pomegranate juice (containing 1.5 millimoles of polyphenols) every day for three months experienced a reduced risk for atherosclerosis.
The juice was freshly squeezed from handpicked fruit, and the juice was filtered, pasteurised and concentrated. The antioxidant composition included 1979 milligrams per litre (mg/L) of tannins, 384 mg/L of anthocyanins, and 121 mg/L of ellagic acid derivatives.
Ten type-2 diabetics and 10 healthy controls were recruited to the study, and after three months of supplementation, the researchers found that, while pomegranate juice consumption did not affect blood levels of glucose, cholesterol and triglyceride, it did significantly reduce serum lipid peroxides and TBARS levels by 56 and 28 per cent.
Thiobarbituric acid reactive substance (TBARS) is a measure of the extent of oxidation of the LDL-cholesterol, which has been reported to be a major part of the pathogenesis of atherosclerosis, and subsequently heart disease.
It was also reported by Aviram and his colleagues that so-called macrophage cells in the diabetics had a faster uptake of this oxidised LDL than the healthy controls (37 per cent faster), but supplementation with pomegranate juice significantly decreased this uptake by 39 per cent.
"We thus conclude that pomegranate juice consumption by diabetic patients did not worsen the diabetic parameters, but rather resulted in anti-oxidative effects on serum and macrophages, which could contribute to attenuation of atherosclerosis development in these patients," wrote the researchers.
In a follow-on study, to be published in the September issue of Atherosclerosis (Vol. 188, pp. 68-76), Aviram and his colleagues report that the antioxidant activity of the pomegranate juice cannot be attributed solely to the polyphenol content of the fruit, but that some credit must also go to the sugar content.
"[The] antioxidative/antiatherogenic properties of the pomegranate juice were mainly attributed to the high content, as well as the unique type of pomegranate polyphenols," reports the second article.
"However, the capacity of pomegranate juice to decrease macrophages peroxide levels was greater than the of effect of the pomegranate juice purified polyphenols… the pomegranate juice sugar fraction may also contribute to the antioxidative properties."
The UK's leading retailer Tesco said last year that sales of pomegranate juice were up 300 per cent since the start of the 2005, and it was now selling close to 500,000 litres per week.