Adding powdered tart cherries to the diet may lower cholesterol, lead to less fat storage and improve antioxidant defences, says a rat study from the US with implications for metabolic syndrome.
The results, presented at Experimental Biology 2007 in Washington, D.C., reports that the antioxidant-rich cherries achieved significant improvements in health measures at relatively low levels that could easily be achieved in the diet.
"We are enthusiastic about the findings that tart cherries conferred these beneficial effects at such a modest daily intake," said lead researcher E. Mitchell Seymour from the University of Michigan Health System
Metabolic syndrome (MetS) is a condition characterised by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type-2 diabetes and CVD.
Fifteen per cent of adult Europeans are estimated to be affected by MetS, while the US statistic is estimated to be a whopping 32 per cent.
The researchers used 48 six-week old male Dahl Salt-Sensitive rats, a strain of rats susceptible to salt-linked high blood pressure, high cholesterol and impaired glucose tolerance, and fed them a carbohydrate-enriched diet or a diet that, by weight, included one or 10 per cent cherries for 90 days.
Seymour and co-workers told attendees in Washington D.C. that both cherry-supplemented groups had significantly lower levels of total cholesterol, triglyceride, glucose and insulin than those of the rats that did not receive cherries.
Plasma antioxidant levels also increased, as measured by Trolox equivalent antioxidant capacity (TEAC). The rats that received cherries had higher antioxidant capacity, indicating lower oxidative stress in their bodies, than those that did not, said the researchers.
They also report that no toxic effects were seen for either of the cherry doses.
"Rats fed tart cherries as one per cent of their total diet had reduced markers of metabolic syndrome," said Seymour. "Previous research by other groups studied pure anthocyanin compounds rather than anthocyanin-containing whole foods, and they used concentrations of anthocyanins that would be very difficult if not impossible to obtain in the diet."
The work is ongoing, said the researchers with research being carried out in animals prone to both obesity and diabetes. Additionally, a team of researchers from the University of Michigan is reported to be launching a small clinical trial to start to investigate if similar findings are achievable in humans.
The study was supported financially by the Cherry Marketing Institute, a trade association for the cherry industry.
"These data from whole tart cherries join other findings that suggest a correlation between anthocyanin intake and reductions in cardiovascular and metabolic risk factors," said co-researcher Steven Bolling. "But there is still a long way to go before we can advocate any course of action for humans. Still, the growing body of knowledge is encouraging."
Interest in tart cherries has previously focused on sports nutrition. One previous study (Journal of Nutrition, 2006, Vol. 136, pp. 981-986) reported that a daily consumption of 45 cherries could reduce circulating concentrations of inflammatory markers, with the researchers propose that the flavonoids and anthocyanins in the cherries exert an anti-inflammatory effect and may lessen the damage response to exercise.
Source: Experimental Biology 2007, Washington, D.C.
Authors: E.M. Seymour, S. Bolling et al.