Compounds found chocolate, berries and tea lower insulin resistance improve glucose control
Laboratory findings suggest that several flavonoid subclasses are involved in glucose metabolism, but there is limited clinical and epidemiological data available.
In this new study Professor Aedin Cassidy, MSc, PhD, Department of Nutrition at University of East Anglia (UEA) Norwich Medical School and colleagues examined associations between habitual intake of flavonoid subclasses, insulin resistance, and related inflammatory biomarkers.
This cross-sectional study included 1,997, aged to 75 years Twins Uk who completed a food questionnaire designed to estimate total dietary flavonoid intake as well as intakes from six flavonoid subclasses ((flavanones, anthocyanins, flavan-3-ols, polymeric flavonoids, flavonols, flavones). 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.
"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."
Higher intakes of both anthocyanins and flavones were associated with improvements in insulin resistance and hs-CRP. These associations were found with intakes readily achieved in the diet. The observed reduction in insulin levels was similar to that reported previously for other lifestyle factors. Dose–response trials are needed to ascertain optimal intakes for the potential reduction of type 2 diabetes risk, according to the researchers.
"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, said Professor 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.
"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.
Professor Tim Spector, MB, MSc, MD, FRCP, Professor of Genetic Epidemiology at Kings College, London, and Director of the Department of Twin Research and Genetic Epidemiology at St Thomas’ Hospital, London, and research collaborator commented ‘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 randomized trials and in people developing early diabetes."
This study is published in the Journal of Nutrition