Glycemia and insulinemia in healthy subjects after lactose-equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins.
BACKGROUND
Milk products deviate from other carbohydrate-containing foods in that they produce high insulin responses, despite their low GI. The insulinotropic mechanism of milk has not been elucidated.


OBJECTIVE
The objective 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 [glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1] in healthy subjects.


METHODS
Twelve healthy volunteers were served test meals consisting of reconstituted milk, cheese, whey, cod, and wheat gluten with equivalent amounts of lactose. An equicarbohydrate load of white-wheat bread was used as a reference meal.


RESULTS
A correlation was found between postprandial insulin responses and early increments in plasma amino acids; the strongest correlations were seen for leucine, valine, lysine, and isoleucine. A correlation was also obtained between responses of insulin and GIP concentrations. Reconstituted milk powder and whey had substantially lower postprandial glucose areas under the curve (AUCs) than did the bread reference (-62% and -57%, respectively). Whey meal was accompanied by higher AUCs for insulin (90%) and GIP (54%).


CONCLUSIONS
It can be concluded that food proteins differ in their capacity to stimulate insulin release, possibly by differently affecting the early release of incretin hormones and insulinotropic amino acids. Milk proteins have insulinotropic properties; the whey fraction contains the predominating insulin secretagogue.
Nilsson
Mikael
M
Department of Applied Nutrition and Food Chemistry, Lund University, Sweden. mikael.nilsson@inl.lth.se
Stenberg
Marianne
M
Frid
Anders H
AH
Holst
Jens J
JJ
Björck
Inger M E
IM
D000328:Adult; D000596:Amino Acids / Q000097:blood*; D019540:Area Under Curve; D001786:Blood Glucose / Q000187:drug effects*; D004032:Diet; D005260:Female; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D019518:Postprandial Period
D000596:Amino Acids; D001786:Blood Glucose; D007328:Insulin; D008894:Milk Proteins