Glycemic index, postprandial glycemia, and the shape of the curve in healthy subjects: analysis of a database of more than 1000 foods
2009
Brand-Miller, Jennie C. | Stockmann, Karola | Atkinson, Fiona | Petocz, Peter | Denyer, Gareth
BACKGROUND: The glycemic index (GI) characterizes foods by using the incremental area under the glycemic response curve relative to a similar amount of oral glucose. Its ability to differentiate between curves of different shapes, the peak response, and other aspects of the glycemic response is debatable. OBJECTIVE: The objective was to explore the association between a food's GI and the shape of the curve in healthy individuals. DESIGN: A large database of 1126 foods tested by standardized GI methodology in 8-12 healthy subjects was analyzed systematically. Each food's absolute and incremental blood glucose concentrations were compared at individual time points with the GI. The average curve was generated for low-GI ([less-than or equal to]55), medium-GI (56-69), and high-GI (greater-than-or-equal70) foods within major food categories. RESULTS: The GI of individual foods was found to correlate strongly with the incremental and actual peak (Spearman's correlations of r = 0.76 and r = 0.73, respectively), incremental and actual glucose concentration at 60 min (r = 0.70 and r = 0.66, respectively), and maximum amplitude of glucose excursion (r = 0.68) (all P < 0.001). In contrast, there was only a weak correlation between the food's GI and the 120-min glucose concentration (incremental r = 0.20, P < 0.001; absolute r = 0.16, P < 0.001). Within food groups, the mean GI, 30- and 60-min glucose concentrations, and maximum amplitude of glucose excursion varied significantly for foods classified as having a low, medium, or high GI (P < 0.001). CONCLUSIONS: The GI provides a good summary of postprandial glycemia. It predicts the peak (or near peak) response, the maximum glucose fluctuation, and other attributes of the response curve.
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