Plasma Amino Acid Concentrations After the Ingestion of Dairy and Collagen Proteins, in Healthy Active Males

Abstract

Introduction: Recent evidence suggests that the consumption of essential amino acids (AA) and/or those abundantly present in collagen may have the capacity to influence the synthesis of new collagen in ligaments and tendons, when tissue perfusion is optimized (e.g., during exercise). However, little is currently known about the bioavailability of these AAs in blood after the consumption of various collagen and diary protein sources: such information is needed to develop potentially useful dietary and supplement intake strategies.Objectives: The aim of the current study was to characterize blood AA concentrations in response to consumption of collagen and dairy protein sources; specifically, maximum concentrations, the timing of maximum concentration, and total (area under the curve) exposure above baseline.Methods: A 20 g serve of various dairy and collagen proteins, and a 300 mL serve of bone broth were consumed by healthy, recreationally active males after an overnight fast. Blood samples were drawn every 20 min for a total of 180 min, for analysis of plasma AA concentrations. Total AA, essential AA and collagen specific AAs were analyzed for maximum concentration, timing of peak, and area under the curve.Results: In general, protein intake was associated with a similar increase in total and collagen specific AAs, except for collagen proteins being a superior source of glycine (683 ± 166 μmol/L) compared to 260 ± 65 μmol/L for dairy proteins (P < 0.0001), whilst dairy proteins were a superior source of leucine (267 ± 77 μmol/L) compared to 189 ± μmol/L for collagen proteins (P < 0.04). Although there were several differences in the bioavailability of hydrolysed compared to non-hydrolysed proteins, this only reached statistical significance within the dairy proteins, but not for collagen proteins.Conclusions: The intake of collagen proteins result in higher plasma peaks of glycine, whilst the intake of dairy proteins result in higher plasma peaks of leucine. This information may support further investigations, and identification of key AAs that may support exercise in the synthesis of collagen.

Casein Ingestion Does Not Increase Muscle Connective Tissue Protein Synthesis Rates

“…3 A/B). Our findings align well with Alcock et al ( 33 ), who recently demonstrated that the ingestion of calcium caseinate and hydrolyzed casein protein do not provide sufficient glycine to increase postprandial plasma glycine availability. This is attributed to the fact that casein, like many other protein sources, does not contain much glycine (2%) when compared with other amino acids, such as leucine (10%) or proline (11%) ( 34 ).…”

The impact of collagen protein ingestion on musculoskeletal connective tissue remodeling: a narrative review

“…For instance, it has been speculated that protein sources delivering large amounts of the key amino acids used for connective tissue protein synthesis (ie, glycine and proline) may be more suitable for facilitating increased connective tissue protein synthesis rates. 13 , 14 , 89 , 90 This hypothesis is discussed in the following sections.…”

“…It has been proposed, therefore, that the hydrolyzation of collagen protein sources may enhance collagen protein digestion and amino acid absorption. However, Alcock et al 90 have recently examined plasma amino acid profiles in human volunteers after the ingestion of either 20 g of gelatin or 20 g of hydrolyzed collagen. The ingestion of both collagen sources resulted in similar peak glycine concentrations, and no differences were observed in total plasma amino acid availability (incremental area under the curve), despite the apparently lower molecular weight of hydrolyzed collagen.…”

Potential Relevance of Bioactive Peptides in Sports Nutrition

“…Exercise-induced adaptions as well as nutrition seems to influence connective tissue. More specifically, its alterations of material and morphological adaptions after supplementation of biologically active peptides have gained increasing attention in the scientific community [103].…”

“…Athletes show an increased risk of articular cartilage lesions leading to functional joint pain [120]. One therapeutic attempt includes the treatment and prevention of degenerative articular processes by stimulation of collagen synthesis with biologically active peptides [103].…”