Evaluation of Five Different Methods for Calculating Glycemic Index Values of Foods
Aim: The purpose of this study was to compare the glycemic index values of potatoes, cooked with different methods and calculated by using different calculation methods. Subjects and Methods: This study was conducted over 12 healthy adult (4 male, 8 female) volunteers aged between 19 and 35 years (24±3.81) with a normal body mass index (21.58±2.14 kg/m2) and without any metabolic and endocrine disease. Individuals consumed reference (glucose and white bread) and test foods after an average of 10-12 hours of night fasting. Duplicate capillary blood glucose measurements were taken at 0., 15., 30., 45., 60., 90., and 120. minutes. Volunteers consume 35 min. boiled potato and 35min. boiled than cooled for 24 hours at +4°C potato. Tests and reference foods area under curve values were calculated for total area under curve, Incremental area until first return to baseline (incremental AUCcut), The area over the baseline under the curve, ignoring area beneath the curve (incremental AUC), Incremental area using the lowest blood glucose as the baseline (incremental AUCmin), The net incremental AUC (apply trapezoid rule for all increments positive and negative) (net incremental AUC). Results: The five different areas under curves for the test and reference foods were calculated. The incremental area values under the curve calculated for the test and reference nutrients were 2214.1 for glucose, 1669.9 for white bread, 1204.8 for 35 minutes boiled potatoes, 1533.7 for 35 minutes boiled and stored at +4°C for 24 hours. Conclusion: Glycemic index of the foods can be calculated by different areas under curve which seen after glucose containing food consumption. Depending on the calculation method used, the glycemic index value of the food changes. Therefore, the correct method should be preferred in order to calculate accurate glycemic index value of foods. It has been determined by FAO / WHO committee of experts that the most appropriate method for calculating the glycemic index value of foods is the incremental area under the curve.