Metabolic response to glucose ingested with various amounts of protein.
Seven healthy, normal-weight subjects were fed breakfasts of 50 g protein, 50 g glucose, and 10, 30, or 50 g protein plus 50 g glucose in random sequence. Plasma glucose, insulin, C peptide, glucagon, nonesterified fatty acids, and alpha-amino nitrogen were then measured from samples obtained over 4 h. The postmeal net area of each response curve was calculated. Ingestion of 50 g protein alone did not change the serum glucose concentration. The various amounts of protein ingested with 50 g glucose also did not alter the serum glucose response compared with that observed with 50 g glucose alone. Ingestion of the various amounts of protein also did not result in a further increase in insulin concentration when ingested with glucose, except with the 50-g-protein dose. This increase was modest. Ingestion of glucose resulted in a decrease in alpha-amino nitrogen and glucagon concentrations whereas ingestion of protein increased them as expected. Additions of progressively larger amounts of protein to the glucose meal resulted in a progressive increase in the alpha-amino-nitrogen- and glucagon-area responses. The relationship was curvilinear for both the alpha-amino-nitrogen response and the glucagon response. The null point, that is, the protein dose ingested with 50 g glucose at which there would be no change in area response, was estimated to be 9 g protein for alpha-amino nitrogen and 5 g protein for glucagon.
Westphal
S A
SA
Section of Endocrinology, Metabolism, and Nutrition, VA Medical Center, Minneapolis, MN 55417.
Gannon
M C
MC
Nuttall
F Q
FQ
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood; D004044:Dietary Proteins / Q000008:administration & dosage*; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000097:blood*
D001786:Blood Glucose; D002096:C-Peptide; D004044:Dietary Proteins; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005934:Glucagon; D005947:Glucose; D009584:Nitrogen