Plasma Amino Acid Concentrations After the Ingestion of Dairy and Collagen Proteins, in Healthy Active Males.
Level 3 - non-randomized controlled study
Comparative pharmacokinetic intervention study with human participants; randomization protocol is not specified in the abstract.
PubMed 31681789 · doi:10.3389/fnut.2019.00163
What was done
Healthy, recreationally active males consumed 20 g servings of various dairy and collagen proteins, as well as a 300 mL serving of bone broth, following an overnight fast. Blood samples were collected every 20 minutes across a 180-minute postprandial period to analyze total amino acids, essential amino acids, and collagen-specific amino acids for maximum concentration, time to peak, and area under the curve, including comparisons between hydrolyzed and non-hydrolyzed forms.
What was found
Protein intake produced generally similar increases in total and collagen-specific amino acids, with specific significant differences: - Collagen protein resulted in significantly higher peak plasma glycine (683 ± 166 μmol/L) compared to dairy proteins (260 ± 65 μmol/L, P < 0.0001). - Dairy protein resulted in significantly higher peak plasma leucine (267 ± 77 μmol/L) compared to collagen proteins (189 μmol/L [SD omitted in abstract], P < 0.04). - Bioavailability differences between hydrolyzed and non-hydrolyzed forms reached statistical significance only for dairy proteins, not collagen.
Why it matters
This study quantifies postprandial amino acid bioavailability across different protein sources, confirming that collagen is superior for delivering circulating glycine while dairy is superior for leucine.
Limits
The abstract does not state the sample size (n) or whether the treatment sequence was randomized. The study included only healthy active males and measured acute 180-minute plasma kinetics without assessing muscle or collagen protein synthesis rates.
Cited by
- supports Collagen protein composition is approximately 50% proline and glycine.