In the United Kingdom from 1993 to 2011, the proportion of people who were overweight and obese increased from 58 to 65 % in men and from 49 to 58 % in women. There was also an increase in related comorbidities including type 2 diabetes, which is predicted to be the 7th leading cause of death by 2030. The modification of food is becoming an attractive option in obesity management and disease prevention with much interest recently focused on the role of plant extracts and secondary plant compounds such as polyphenols as potential functional food additives for improving glycaemic control. The aim of this PhD was to assess the effect of a variety of polyphenol rich sources including green, black and white teas, and also green tea extract, grape seed extract, resveratrol, and baobab fruit extract, on starch digestion and on markers of glycaemia. Throughout an in vitro digestion procedure, green tea and all of the polyphenol rich extracts were found to reduce starch digestion from white bread, and this effect was dose specific. These same doses of green tea extract and baobab fruit extract added into white bread were shown to have no effect on reducing the glycaemic response in healthy subjects, and therefore there may be inconstancies between in vitro and in vivo methods. However, although having no effect on glycaemia, baobab addition to white bread was shown to reduce the postprandial insulin response. Conversely, baobab fruit extract consumed as a solution at higher doses in combination with white bread was found to reduce the postprandial glycaemic response. Therefore baobab fruit extract may show potential as a functional food additive for improving health, and more specifically for alleviating markers of abnormal glucose metabolism.
Coe, Shelly A.
Faculty of Health and Life SciencesDepartment of Biological and Medical Sciences
Year: 2014
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