Published in the journal Diabetes Care, the findings of the 12-month trial provide further evidence that diet offers extra protection to those at high risk of cardiovascular events. The results also suggest that regular consumption of flavonoid-rich foods can help in the management of diabetes itself.
Diabetes is an increasing global problem, with recent research suggesting that complications of the disease account for 7% of all deaths and 12% of healthcare costs.
Flavonoids occur in foods such as berries, tea and chocolate, though the researchers have emphasised that the results do not mean that women with type 2 diabetes should eat more chocolate. This is because commercially available chocolate does not contain nearly as much of it as the women in this trial consumed, and eating too much chocolate may adversely affect weight unless the diet is balanced for total energy intake.
93 postmenopausal women with type 2 diabetes took part in the trial. The age of participants ranged from 51-74 years. Half were given two small bars of flavonoid-enriched chocolate each day and half were given placebo chocolate bars. Those receiving the extra flavonoids reduced their risk of suffering a heart attack in the next decade by 3.4% – an important effect for a dietary intervention. Their insulin resistance and cholesterol levels were significantly reduced by the flavonoids.
Lead researcher, Prof Aedin Cassidy of the Department of Nutrition, Norwich Medical School at UEA, says: “These results are significant from a public health perspective because they provide further concrete evidence that diet has a beneficial clinical effect over and above conventional drug treatment.”
Flavonoids are bioactive constituents which occur naturally in various foods and drinks including tea, red wine, many fruits and vegetables, and dark chocolate. The chocolate bars used in the trial were specially formulated with the help of a Belgian chocolatier to provide a high dose of two flavonoid sub-classes – flavan-3-ols which are found in cocoa and tea, and isoflavones which are found in soy.
Prof Cassidy said she was not advocating eating more commercially available chocolate because many commercial chocolates do not contain high levels of the beneficial flavonoids.
Previous studies have shown that dietary flavonoids reduce the risk factors for heart disease in healthy people. However, this is the first long-term study to examine their effect on a medicated, high risk group.
Funded by Diabetes UK, the study was led by UEA in collaboration with colleagues at the Elsie Bertram Diabetes Centre, Norfolk and Norwich University Hospital (NNUH) and the Institute of Food Research (IFR).
Dr Ketan Dhatariya, one of the researchers and a consultant in diabetes at the Norfolk and Norwich University Hospital, says: “This is an important result. We are not saying that people with diabetes should be eating lots of chocolate, but that foods that are rich in flavonoids can potentially reduce the risk of heart attacks and strokes, which sadly remain the leading causes of premature death in this group of women.”
Further research is now needed to determine the relative influence of the two flavonoid sub-classes featured in this study, and to examine whether similar effects are observed in male patients with type 2 diabetes or in other patient groups.
Source: UEA
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