The influence of ethnicity, body composition and food components on glycaemic response/index

The concept of glycaemic response (GR) and glycaemic index (GI) has become a topic of great nutritional interest. The overall theme of this thesis was to understand the role of body composition, ethnicity and type of diet on glycaemic response. The GI refers to the blood glucose raising potential of carbohydrate foods. A series of experiments were performed to address the above issues. A question frequently raised in relation to the GI is whether results obtained using Caucasian subjects can be applied to other ethnic groups. In the first series of studies on the GI value of foods determined in three ethnic groups, it was shown that there were no significant differences in either a statistical or biological sense (Asian, Caucasian and African). However, the GI value of foods was affected by body composition, notably percentage fat mass (FM %) and body mass index (8MI), in Asian and Caucasian subjects only. Potato being a widely used staple, unfortunately has a very high GI value. The addition of cheese and baked beans was shown to effectively reduce the GI value of potato-based meals. This observation provided a practical application for potatoes being used as a low GI food source for people interested in maintaining slow glucose release. Following a low GI diet, effective weight loss was achieved in a study conducted over 4 and 8-weeks in Caucasian subjects. Adhering to a low GI diet resulted in a reduction in energy, carbohydrate and fat intakes and an increase in protein and fibre intakes. These together appear to have contributed to the weight loss. Finally, on investigating the role of ethnicity on anthropometric and body composition indicators, data showed that normal weight Asian subjects had higher FM % compared to normal weight Caucasian subjects. Asian subjects showed a higher percentage of risk factors associated with the metabolic syndrome components compared to the Caucasian subjects. It is concluded that further studies are performed to explore the relationships between body composition, percentage fat mass, BMI and the glycaemic response in other ethnic groups