The glycemic index of foods influences postprandial insulin-like growth factor-binding protein responses in lean young subjects.
BACKGROUND
Growth in normal and malignant tissues has been linked to hyperinsulinemia and insulin-like growth factors (IGFs). We hypothesized that IGF and IGF-binding protein (IGFBP) responses may be acutely affected by differences in the glycemic index (GI) of foods.


OBJECTIVE
We compared the postprandial responses of IGFs and IGFBP to 2 foods of similar macronutrient composition but with greatly different GIs-pearled barley (GI: 25) and instant mashed potato (GI: 85).


METHODS
Ten young lean subjects consumed 50-g carbohydrate portions of the 2 foods or water (extended fast) in random order after an overnight fast. Capillary blood was collected at regular intervals over 4 h for measurement of blood glucose, insulin, and components of the IGF system.


RESULTS
Serum IGFBP-1 declined markedly after both meals, but the mean (+/-SEM) change at 4 h was significantly (P < 0.01) more prolonged after the low-GI meal (-55 +/- 20 ng/mL) than after the high-GI meal (-13 +/- 15 ng/mL). Conversely, the change in serum IGFBP-3 concentration at 4 h was significantly (P < 0.05) higher after the low-GI meal (251 +/- 102 ng/mL) than after the high-GI meal (-110 +/- 96 ng/mL); the same pattern was observed at 2 h. Changes in IGFBP-2, free IGF-1, and total IGF-1 responses were minimal and did not differ significantly from those during the 4-h fast.


CONCLUSIONS
Acute changes in IGFBP-3 after low-GI and high-GI foods may provide a biologic mechanism linking cell multiplication with greater consumption of high-GI carbohydrates.
Brand-Miller
Jennie C
JC
Human Nutrition Unit, School of Molecular and Microbial Biosciences, University of Sydney, Sydney, Australia. j.brandmiller@mmb.usyd.edu.au
Liu
Vicki
V
Petocz
Peter
P
Baxter
Robert C
RC
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000097:blood; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D019518:Postprandial Period; D013851:Thinness
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I