.

This study was carried out to investigate the effect of four yam species on blood glucose response and to determine their glycaemic index (GI) values. Four different species of yam Dioscorea spp (D. rotundata, D. alata, D. dumentorum and D. cayenensis) obtained from the open market in Akure, Nigeria were peeled, washed, cubed, weighed and boiled separately for 20 mins. Each of the yams was served as a meal in 50 g portions to ten healthy subjects (7 males and 3 females, average BMI=20.6kg/m2, average age=26 years). The subjects were required to go through the study protocol on five separate occasions (four tests for the test yam samples and one for the reference food i.e. glucose) after an overnight fast before being served the meals. Venous blood samples were taken immediately before (0 min) and 30, 60, 90 and 120 mins after consumption of the test foods. The blood glucose response was obtained by calculating the incremental area under the curve (IAUC) and the corresponding GI for each yam was determined and compared. The mean areas under blood glucose curves were 666.00, 646.41, 588.77 and 615.64 mol min/L for D. rotundata, D. alata, D. dumentorum and D. cayenensis, respectively, with corresponding G.I values of 106.92%, 103.78%, 94.52% and 98.83%. This study showed that all the four species of yams tested could be categorised as having high GI with no significant difference (P<0.05) among the species.