(16-07-09) Effect of the glycemic index of carbohydrates on day-long (10 h) profiles of plasma glucose, insulin, cholecystokinin and ghrelin

R C Reynolds1, K S Stockmann1, F S Atkinson1, G S Denyer1 and J C Brand-Miller1

1Human Nutrition Unit, School of Molecular and Microbial Biosciences (G08), The University of Sydney, NSW, Australia
Correspondence: Professor JC Brand-Miller, Human Nutrition Unit, G08 School of Molecular and Microbial Biosciences, The University of Sydney, NSW 2006, Australia. E-mail: [email protected]
Received 15 May 2008; Revised 19 September 2008; Accepted 23 September 2008; Published online 29 October 2008.
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Abstract
Background:

Low glycemic index (GI) carbohydrates have been linked to increased satiety. The drive to eat may be mediated by postprandial changes in glucose, insulin and gut peptides.
Objective:

To investigate the effect of a low and a high GI diet on day-long (10 h) blood concentrations of glucose, insulin, cholecystokinin (CCK) and ghrelin (GHR).
Design:

Subjects (n=12) consumed a high and a low GI diet in a randomized, crossover design, consisting of four meals that were matched for macronutrients and fibre, and differed only in carbohydrate quality (GI). Blood was sampled every 30?60 min and assayed for glucose, insulin, CCK and GHR.
Results:

The high GI diet resulted in significantly higher glucose and insulin mean incremental areas under the curve (IAUC, P=0.027 and P=0.001 respectively). CCK concentration was 59% higher during the first 7 h of the low GI diet (394 95 pmol/l min) vs the high GI diet (163 38 pmol/l min, P=0.046), but there was no difference over 10 h (P=0.224). GHR concentration was inversely correlated with insulin concentration (Pearson correlation -0.48, P=0.007), but did not differ significantly between the low and high GI diets.
Conclusions:

Mixed meals of lower GI are associated with lower day-long concentrations of glucose and insulin, and higher CCK after breakfast, morning tea and lunch. This metabolic profile could mediate differences in satiety and hunger seen in some, but not all, studies.

Source: European Journal of Clinical Nutrition (2009) 63, 872?878; doi:10.1038/ejcn.2008.52; published online 29 October 2008

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