Glycemic Index of Selected Foods in Jamaica

Background: Fruits, vegetables and legumes for their complex carbohydrates, dietary fiber and micronutrients, should form an essential part of every diet. In order to give good dietary advice to diabetic patients, it is necessary to know the glycemic index of foods commonly consumed locally. The objective of this study was to determine the Glycemic Index (GI) and Glycemic Load (GL) of commonly available and consumed Guava (Psidium guajava), Watermelon (Citrullus vulgaris), Gungo (Cajanus cajan), Papaya (Carica papaya) and tomato (Solanum lycopersicum) in Jamaica. Methods: Ten (10) healthy Jamaican subjects (5 males, 5 females) with mean age 30 ± 2 years and mean BMI 25 ± 1 kg/m2 were recruited to the study. Using a non-blind, crossover design trial, the subjects consumed 50 (or 25) grams of available carbohydrate portions of glucose (standard food) and test foods after an overnight fast and their serum glucose levels were determined at 0, 15, 30, 45, 60, 90 and 120 minutes after the consumption of each test food. Glucose was tested on three separate occasions, and the test foods once. The GI value was calculated geometrically by expressing the Incremental Area Under the Blood Glucose Curve (IAUC) for the test foods as a percentage of each subject's average IAUC for the standard food. Results: The results indicated that the IAUC for Watermelon (95 ± 11) was significantly higher (p<0.05) than that of Tomato (37 ± 12), and Gungo (58 ± 13). The differences in IAUC of Watermelon (95 ± 11), Guava (83 ± 27) and Papaya (80 ± 7) were not statistically significant. Similarly, there was no significant difference in GI among the samples studied. Conclusion: Tomato, Gungo, Papaya Watermelon and Guava were shown to have low glycemic index and glycemic load values.