Published in the Journal of Nutrition, the new study suggests that eating high levels of flavonoids -including anthocyanins and other compounds that are found in berries, tea, and chocolate - could offer protection from type 2 diabetes by lowering insulin resistance and improving blood glucose regulation.
Led by Professor Aedin Cassidy from the University of East Anglia, UK, the study of almost 2,000 people also linked flavonoid consumption with lower inflammation which, when chronic, is associated with diabetes, obesity, cardiovascular disease, and cancer.
"Our research looked at the benefits of eating certain sub-groups of flavanoids," explained Cassidy. "We focused on flavones, which are found in herbs and vegetables such as parsley, thyme, and celery, and anthocyanins, found in berries, red grapes, wine and other red or blue-coloured fruits and vegetables."
"This is one of the first large-scale human studies to look at how these powerful bioactive compounds might reduce the risk of diabetes," she added - explaining that laboratory studies have suggested that such compounds may modulate blood glucose regulation – and so affect the risk of type 2 diabetes.
"But until now little has been know about how habitual intakes might affect insulin resistance, blood glucose regulation and inflammation in humans."
Cassidy and her team studied data from 1,997 healthy women volunteers from the TwinsUK study - all of whom had completed a food questionnaire designed to estimate total dietary flavonoid intake as well as intakes from six flavonoid subclasses.
Blood samples were also analysed for evidence of both glucose regulation and inflammation, while insulin resistance - a known risk factor for type 2 diabetes - was assessed using an equation that considered both fasting insulin and glucose levels.
"We found that those who consumed plenty of anthocyanins and flavones had lower insulin resistance," said Cassidy. "We also found that those who ate the most anthocyanins were least likely to suffer chronic inflammation – which is associated with many of today's most pressing health concerns including diabetes, obesity, cardiovascular disease, and cancer."
The team also revealed that those who consumed the most flavone compounds had improved levels of a protein known as adiponectin which helps regulate a number of metabolic processes including glucose levels.
However Cassidy added that her research has not yet suggested exactly how much of these compounds are needed to potentially reduce the risk of type 2 diabetes. She did note, however, that the observed reduction in insulin levels was 'similar' to those previously reported by studies looking at other lifestyle factors.
"Dose–response trials are needed to ascertain optimal intakes for the potential reduction of type 2 diabetes risk," the team concluded.
Source: Journal of Nutrition
Published online ahead of print, doi: 10.3945/jn.113.184358
"Intakes of Anthocyanins and Flavones Are Associated with Biomarkers of Insulin Resistance and Inflammation in Women"
Authors: Amy Jennings, Ailsa A. Welch, et al