Type 2 diabetes prevalence has increased dramatically in the last decades. Diet is the first and main route for reducing diabetes risk. However, specific diets may benefit some more than others. A literature review assessing the effects of grape seed extracts and bilberry extracts on glucose and lipid metabolism in humans revealed: 320mg/d bilberry extract could lower low-density lipoproteins (LDL) by 10%, total cholesterol (TC) by 3.5%, and increase high-density lipoproteins (HDL) by 14% on average in 3 compared intervention studies. A dose of 100mg/d to 600mg/d grape seed extract in six intervention studies lowered HbA1c by 0.5%, TC by 2.8%, LDL by 1% and HDL by 6% on average. We are currently preparing a human intervention study to assess whether a commercial blend of grape seed and bilberry extract beneficially affects glucose and lipid metabolism in human subjects from various ethnic origins and at risk for developing metabolic disease, and determine which factors (bioavailability of anthocyanins and procyanidins, age, sex, baseline metabolic health including BMI, ethnicity) contribute to a beneficial response. For this, we are currently characterising the composition and metabolism of extracts of anthocyanin and procyanidin using a simulated digestion model. We are also fermenting pre-digested samples with faecal inocula to investigate the influence of gut microbiota on the digestion. We have now optimised and validated methodology to measure HbA1c and total/HDL cholesterol, yielding a recovery of >95% and ~80%, respectively. HbA1c in dried blood spots (DBS) provided stable results over a period of 124 days. We are currently optimising and validating the measurement of catechin and epicatechin, which are major metabolites of procyanidins, in DBS for use in the human study. The collection of DBS will allow subjects from all over the UK to participate in the study from a home setting.
Acknowledgements: By-Health
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