GLYCAEMIC INDICES OF MAIZE, ACHA, WHEAT AND OAT IN WISTAR RATS

ABSTRACT

This study was conducted to measure the glycemic index and blood glucose response of staple foods consumed in Nigeria in healthy Wistar rats. The test food samples Maize (Zea mays), Wheat (Triticum spp), Acha (Digitaria exilis) and Oat (Elkris super oat) were formulated with palm kernel cake, rice husk/bran, soya beans, crayfish, bone meal, premix and salt into diets in the laboratory of the Department of Home Science, Nutrition and Dietetics, University of Nigeria, Nsukka. Proximate compositions of the flours were determined using standard method. The rats were divided into six (6) groups of three (3) rats each. Group 1 (the negative control) received (0.4 ml distilled water), while group 2 (the positive control) received 2 g/kg b.w of glucose dissolved in 0.4 ml of distilled water orally using gastric cannula. Rats in groups 3 to 6 also received 2 g/kg b.w of glucose in 0.4 ml distilled water and on a separate day received 2 g/kg b.w of the test diets of maize, acha, wheat and oat and the blood glucose level recorded at 15, 30, 45, 60, 90 and 120 min intervals. Result of proximate analysis showed that the carbohydrate content of maize diet (62.14 %) was significantly higher (p < 0.05) than oat (60.56%), acha (59.90%) and wheat (57.62%). Wheat had the highest protein content (19 %), followed by oat (16.45%), maize (15.46%) and acha (9.57%). The moisture content of wheat (6.90%) and oat (8.67%) diets were however lower when compared to acha (11.42%) and maize (10.09%) diet. Acha had the highest fat percentage (5.40%) and oat with the least (3.00%). The ash content of acha (4.33%) was higher than wheat (3.96%) and oats (2.84%). Acha (9.36%) also had the highest fibre content and its values were significantly (p < 0.05) higher than wheat (7.87%), oat (8.50%) and maize (4.52%). The mean Incremental Area under Curve (IAUC) of the test diets were significantly (p < 0.05) lower than the standard glucose (positive control). Regarding the GI, the study showed that the GI of maize (76%), wheat (69.4%), acha (57.5%) and oat (48.1%). It could be concluded that maize had a high glycaemic index while wheat and acha are intermediate glycaemic index foods and oat (Elkris Super Oat) a low glycaemic index food. Thus, the oat (Elkris super oat) having a low glycaemic index is a preferable diet in achieving better glycaemic control.