Different Proteins May Have Varying Insulinotropic Properties CME
News Author: Laurie Barclay, MD
CME Author: Désirée Lie, MD, MSEd
Nov. 17, 2004 — Different proteins have varying insulinotropic properties, and the whey fraction of milk is the predominant insulin secretagogue, according to the results of a study published in the November issue of the
American Journal of Clinical Nutrition.
"Milk products deviate from other carbohydrate-containing foods in that they produce high insulin responses, despite their low glycemic index (GI)," write Mikael Nilsson, MD, from Lund University in Sweden, and colleagues. "The insulinotropic mechanism of milk has not been elucidated."
The objective of this study was to evaluate the effect of common dietary sources of animal or vegetable proteins on concentrations of postprandial blood glucose, insulin, amino acids, and incretin hormones, including glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1, in 12 healthy volunteers. These subjects ate test meals consisting of reconstituted milk, cheese, whey, cod, and wheat gluten with equivalent amounts of lactose, with an equicarbohydrate load of white-wheat bread used as a reference meal.
Postprandial insulin responses were correlated with early increments in plasma amino acids, with the strongest correlations for leucine, valine, lysine, and isoleucine. There was also a correlation between responses of insulin and GIP concentrations.
Compared with the bread reference, reconstituted milk powder and whey had substantially lower postprandial glucose areas under the curve (AUCs) (-62% and -57%, respectively). The whey meal was associated with higher AUCs for insulin (90%) and GIP (54%).
"Food proteins differ in their capacity to stimulate insulin release, possibly by differently affecting the early release of incretin hormones and insulinotropic amino acids," the authors write. "Milk proteins have insulinotropic properties; the whey fraction contains the predominating insulin secretagogue.... The potential long-term effects of a noncarbohydrate-mediated insulin stimulus on metabolic variables should be evaluated in healthy persons and in persons with a diminished capacity for insulin secretion."
The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, and Direktör Albert Påhlssons stiftelse för forskning och va¨lgörenhet supported this study. None of the authors report a conflict of interest.
Am J Clin Nutr. 2004;80:1246-1253