Flavonoids, which are found in a variety of fruits and vegetables as well as in tea, red wine, chocolate and berries, are thought to boost health in part by combating oxidation, a process in which cell-damaging substances called free radicals accumulate. Oxidative damage can be caused by several factors, especially by those factors on the cellular level. Is is suspected of increasing the risk of diabetes, heart disease, stroke and several other diseases.
Some studies have shown that the risk of cardiovascular disease, diabetes and even cancer decline as consumption of flavonoids rises.
Journal of Nutrition reveal that high intakes of these dietary compounds are associated with lower insulin resistance and better blood glucose regulation.
A study of almost 2,000 people also found that these food groups lower inflammation which, when chronic, is associated with diabetes, obesity, cardiovascular disease, and cancer.
Prof Aedin Cassidy from UEA's Norwich Medical School led the research. She said: "Our research looked at the benefits of eating certain sub-groups of flavanoids. 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.
A recent study from Finland showed that berries may be all you need to blunt a rapid insulin response responsible for long-term weight gain and diabetes. Strawberries, bilberries, lingonberries, and chokeberries offer a means of reducing the risk.
"This is one of the first large-scale human studies to look at how these powerful bioactive compounds might reduce the risk of diabetes. Laboratory studies have shown these types of foods might modulate blood glucose regulation -- affecting 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."
Researchers studied almost 2,000 healthy women volunteers from TwinsUK who had completed a food questionnaire designed to estimate total dietary flavonoid intake as well as intakes from six flavonoid subclasses. Blood samples were analysed for evidence of both glucose regulation and inflammation. Insulin resistance, a hallmark of 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. High insulin resistance is associated with Type 2 diabetes, so what we are seeing is that people who eat foods rich in these two compounds -- such as berries, herbs, red grapes, wine- are less likely to develop the disease.
"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.
"And those who consumed the most flavone compounds had improved levels of a protein (adiponectin) which helps regulate a number of metabolic processes including glucose levels.
"What we don't yet know is exactly how much of these compounds are necessary to potentially reduce the risk of type 2 diabetes," she added.
A previous study in the Journal of Nutrition evaluated the effect of daily dietary supplementation with bioactives in blueberries on whole-body insulin sensitivity in obese, non-diabetic, and insulin-resistant men and women and found that blueberries increased sensitivity to insulin, and may reduce the risk of developing diabetes in at-risk people
Prof Tim Spector, research collaborator and director of the TwinsUK study from King's College London, said: "This is an exciting finding that shows that some components of foods that we consider unhealthy like chocolate or wine may contain some beneficial substances. If we can start to identify and separate these substances we can potentially improve healthy eating. There are many reasons including genetics why people prefer certain foods so we should be cautious until we test them properly in randomised trials and in people developing early diabetes."