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The Postprandial Plasma Amino Acid Response Does Not Differ Following the Ingestion of a Solid Versus a Liquid Milk Protein Product in Healthy Adult Females.

  • 2023-09-01
  • International journal of sport nutrition and exercise metabolism 33(5)
    • Glenn A A van Lieshout
    • Jorn Trommelen
    • Jean Nyakayiru
    • Janneau van Kranenburg
    • Joan M Senden
    • Lex B Verdijk
    • Luc J C van Loon

Study Design

Type
Randomized Controlled Trial (RCT)
Population
Twelve healthy, young females
Methods
randomized cross-over study, ingestion of 20-g milk protein concentrate in solid form (protein bar) or in liquid form (protein drink) with matched ingredients
Blinding
Open-label
Duration
up to 4 hr
Funding
Unclear
Dietary protein digestion and amino acid absorption rates are modulated by numerous factors such as the food matrix. It has been speculated that protein ingested in liquid form is more rapidly digested and absorbed when compared with ingestion in solid form. Here, we assessed the postprandial plasma amino acid availability following ingestion of a single bolus of protein provided in either liquid or solid form. Twelve healthy, young females were included in this randomized cross-over study. On two separate test days, participants ingested 20-g milk protein concentrate in solid form (protein bar) or in liquid form (protein drink). Products were composed of matched ingredients and, thereby, had the same macro- and micronutrient composition. On both test days, arterialized blood samples were collected at regular time intervals for up to 4 hr following protein ingestion to assess the postprandial rise in plasma amino acid concentrations. Protein ingestion robustly elevated circulating plasma amino acid concentrations (p < .001), with no significant differences between treatments (p = .088). The incremental area under the curve of the postprandial rise in total plasma amino acid concentrations did not differ following bar versus drink consumption (160 ± 73 vs. 160 ± 71 mmol·L-1·240 min-1, respectively; 95% confidence interval [-37, 37]; Cohen's dz = 0.003; p = .992). Ingestion of protein in liquid or solid form does not modulate postprandial amino acid availability in healthy, female adults. Any differences in protein digestion and amino acid absorption due to differences in food matrix are not attributed to the protein being consumed as a bar or as a drink.

Research Insights

  • Milk Protein→Increased Amino Acid Concentration

    Protein ingestion robustly elevated circulating plasma amino acid concentrations (p < .001), with no significant differences between treatments (p = .088).

    Effect
    Neutral
    Effect size
    Small
    Dose
    20-g milk protein concentrate
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