Study Finds Flavonoids Reduce Type 2 Diabetes Risk

Consuming a diet rich in flavonoids might reduce your risk of type 2 diabetes. This is according to a new study, published in the peer-reviewed medical journal the Journal of Nutrition, which found that women who consumed more flavonoids –found in tea, berries and, yes, red wine and chocolate – appeared to have less biological signs they were heading for type 2 diabetes. These women had lower insulin resistance and lower insulin levels than those consuming lower levels of flavonoids – but does this mean you can consume as much chocolate and red wine as you want? Probably not.


The study researchers, who came from the University of East Anglia and King’s College London, commented that information from laboratory experiments suggests that several flavonoid subclasses are involved in glucose metabolism – a key part of diabetes. However, according to the NHS website, ‘This study does not give the green light to drink red wine above the recommended levels or to consume chocolate often – any potential benefits of diabetes prevention are likely to be overshadowed by the already known risks of excessive sugar, fat and alcohol consumption, including liver disease, cardiovascular disease, stroke and cancer… A proven method of reducing your risk of type 2 diabetes is to maintain a healthy weight, and contrary to media reports, a diet rich in wine and chocolate is not going to help you with that.’


The researchers used food questionnaires filled in by a group of 1,997 women aged 18 to 76 who were taking part in the Twins UK registry. From these results, they calculated the women’s intake of flavonoids and a range of flavonoid sub-classes from food and drink, and compared them to a number of markers of type 2 diabetes that were measured during a clinical assessment between 1996 and 2000. These markers included fasting blood glucose, insulin, high sensitivity C-reactive protein, plasminogen activator inhibitor and adiponectin. Tea was the main source of total flavonoid (81%), flavan-3-ol (91%), flavonol (63%), and polymer (83%) intake. Grapes, pears, wine and berries contributed >10% of anthocyanin intake, and oranges, wine and peppers to >10% of flavone intake.


The researchers found that those who had a high intake of anthocyanins were significantly more likely to have lower insulin resistance and lower fasting insulin levels. Therefore, the investigators came to the conclusion that ‘the findings of the current study provide an insight into the potential mechanisms by which anthocyanins may act to reduce type 2 diabetes risk and are consistent with previous studies investigating intake of specific flavonoid subclasses and type 2 diabetes risk.’ They added, ‘It is plausible that increasing intakes of anthocyanin-rich foods, such as grapes, berries, and wine, would lead to greater improvements in insulin resistance because in vitro [in the laboratory] studies have shown previously that this is dose-dependent relation.’


However, the NHS website warns, ‘The bottom line is that this study only highlights a possible link and cannot prove cause and effect. A clinical trial is needed before these results can be believed. We would have no problem promoting a diet rich in fresh fruits such as berries and oranges. However, care should be taken with tea; excessive amounts of caffeine may trigger symptoms of irritability and insomnia in some people. As with chocolate and wine, it could be the case that any potential benefit is outweighed by the risk, such as liver disease and obesity.’ Again, however, this is not an excuse to overdo it on more than the recommended levels of chocolate and red wine – or at least, not until a larger study comes to the same conclusions.

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