Dose response of whey protein isolate in addition to a typical mixed meal on blood amino acids and hormonal concentrations.
The purpose was to investigate the effects of a controlled typical 1-day diet supplemented with two different doses of whey protein isolate on blood amino acid profiles and hormonal concentrations following the final meal. Nine males (age: 29.6 ± 6.3 yrs) completed four conditions in random order: a control (C) condition of a typical mixed diet containing ~10% protein (0.8 g·kg1), 65% carbohydrate, and 25% fat; a placebo (P) condition calorically matched with carbohydrate to the whey protein conditions; a low-dose condition of 0.8 grams of whey protein isolate per kilogram body mass per day (g·kg1·d1; W1) in addition to the typical mixed diet; or a high-dose condition of 1.6 g·kg1·d1 (W2) of supplemental whey protein in addition to the typical mixed diet. Following the final meal, significant (p < .05) increases in total amino acids, essential amino acids (EAA), branch-chained amino acids (BCAA), and leucine were observed in plasma with whey protein supplementation while no changes were observed in the control and placebo conditions. There was no significant group difference for glucose, insulin, testosterone, cortisol, or growth hormone. In conclusion, supplementing a typical daily food intake consisting of 0.8 g of protein·kg1·d1 with a whey protein isolate (an additional 0.8 or 1.6 g·kg1·d1) significantly elevated total amino acids, EAA, BCAA, and leucine but had no effect on glucose, insulin, testosterone, cortisol, or growth hormone following the final meal. Future acute and chronic supplementation research examining the physiological and health outcomes associated with elevated amino acid profiles is warranted.
Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Canada.
Scott C
SC
Forbes
Linda
L
McCargar
Paul
P
Jelen
Gordon J
GJ
Bell
D000328:Adult; D000596:Amino Acids / Q000097:blood*; D000597:Amino Acids, Branched-Chain / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D004032:Diet; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D006728:Hormones / Q000097:blood*; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D007930:Leucine / Q000097:blood; D008297:Male; D062407:Meals; D008894:Milk Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D013739:Testosterone / Q000097:blood; D000067816:Whey Proteins; D055815:Young Adult
D000596:Amino Acids; D000597:Amino Acids, Branched-Chain; D001786:Blood Glucose; D006728:Hormones; D007328:Insulin; D008894:Milk Proteins; D000067816:Whey Proteins; D019382:Human Growth Hormone; D013739:Testosterone; D007930:Leucine; D006854:Hydrocortisone