Canadian researchers report that mice prone to obesity, insulin resistance, diabetes and hypertension drinking the blueberry juice were protected against the development of glucose intolerance and diabetes mellitus.
The blueberry juice used in the study was not standard juice but had undergone a transformation using the Serratia vaccinii bacterium.
"Results of this study clearly show that biotransformed blueberry juice has strong anti-obesity and anti-diabetic potential," said lead researcher Pierre Haddad, from the Université de Montréal.
"Biotransformed blueberry juice may represent a novel therapeutic agent, since it decreases hyperglycemia in diabetic mice and can protect young pre-diabetic mice from developing obesity and diabetes."
Blueberries, nature's only 'blue' food, are a rich source of polyphenols, potent antioxidants that include phenolics acids, tannins, flavonols and anthocyanins.
The berries are said to have a number of positive health effects, including cholesterol reduction, and prevention against some cancers and neurodegenerative diseases such as Alzheimer's.
The popularity of the berry has increased in recent years with the publication of more science supporting its health benefits, and an overall consumer move towards 'superfruits' and all things 'antioxidant'.
Writing in the International Journal of Obesity, Dr Haddad and his team used KKAy mice, known as a rodent model of leptin resistance. Leptin is a hormone which plays a role in hunger control. "These mice were an excellent model that closely resembles obesity and obesity-linked type 2 diabetes in humans," explained Dr Haddad.
Incorporation of the juice into their drinking water led to a significant reduction in weight gain. It was also associated with protection against feeling excessively hungry (hyperphagia).
"Consumption of fermented blueberry juice gradually and significantly reduced high blood glucose levels in diabetic mice. After three days, our mice subjects reduced their glycemia levels by 35 per cent," said lead author, Tri Vuong.
Furthermore, when the juice was administered to obese and diabetic mice, the food in take and body weights of the animals were decreased.
“This effect could not fully explain the associated antidiabetic effect because [blueberry juice-drinking] mice still showed lower blood glucose level when compared with pair-fed controls,” stated the researchers.
Commenting on the potential mechanism, the Canadian researchers noted that the effects may be related to a reversal of adiponectin levels, a hormone that regulates a number of metabolic processes.
The researchers note that the bacterial treatment, using a strain of bacteria isolated from the blueberry flora, specifically called Serratia vaccinii, results in an increase in the fruit’s antioxidant effects.
"The identification of the active compounds in biotransformed blueberry juice may result in the discovery of promising new antiobesity and antidiabetic molecules," said Dr Haddad.
Source: International Journal of Obesity
Published online ahead of print, 18 August 2009, doi:10.1038/ijo.2009.149
"Antiobesity and antidiabetic effects of biotransformed blueberry juice in KKAy mice"
Authors: T. Vuong, A. Benhaddou-Andaloussi, A. Brault, D. Harbilas, L.C. Martineau, D. Vallerand, C. Ramassamy, C. Matar, P.S. Haddad