The glycaemic index of indigenous South African foods

Abstract

Objectives: The objective of this study was to determine the glycaemic index (GI) and insulin index (II) of indigenous foods consumed in the Northern Province of South Africa. Design: The GI and II of 10 dishes were determined in 37 healthy student volunteers (18 males, 19 females) within the same range for age and body mass index (BMI). Subjects were divided into four groups of 10. Each group was allocated white bread as the standard and three other dishes. Venous blood samples were used to determine serum glucose and insulin concentrations. Results: The GI of sorghum porridge with added tartaric acid was the lowest (64), while that of samp (130) was the highest. Adding beans to samp lowered the GI to 98. Mabella porridge without sugar had a GI of 124 and with sugar 106, while soft mealiemeal porridge without sugar produced a GI of 117 and with sugar 123. Stiff mealiemeal porridge with nkaka (Cucurbitaceae, Mormordica balsamina L.) had a GI of 105, while adding dried green bean leaf stew to the porridge lowered the GI to 87. Dried bean stew had a low GI (68). Conclusion: The legume-based dishes and acid-added sorghum porridge produced GIs lower than that of bread, while stiff mealiemeal with nkaka or dried bean leaf stew, as well as samp and beans, and mabella with sugar produced insulin indices lower than that of bread. The addition of sugar to soft porridge made from sorghum or mealiemeal did not significantly influence the glycaemic and insulinaemic responses to these foods.