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Rebekah D. Alcock, Gregory C. Shaw, and Louise M. Burke

Intake of dietary sources of collagen may support the synthesis of collagen in varying tissues, with the availability of key amino acids being a likely contributor to its effectiveness. This study analyzed commonly consumed preparations of bone broth (BB) to assess the amount and consistency of its amino acid content. Commercial and laboratory-prepared samples, made with standardized and variable (nonstandardized) protocols, were analyzed for key amino acids (glycine, lysine, proline, leucine, hydroxyproline, and hydroxylysine). The main finding of this study was that amino acid concentrations in BB made to a standardized recipe were significantly lower for hydroxyproline, glycine, and proline (p = .003) and hydroxylysine, leucine, and lysine (p = .004) than those provided by a potentially therapeutic dose (20 g) of reference collagen supplements (p > .05). There was a large variability in the amino acid content of BB made to nonstandardized recipes, with the highest levels of all amino acids found within the café-prepared varieties. For standardized preparations, commercial BBs were lower in all amino acids than the self-prepared varieties. There were no differences (p > .05) in the amino acid content of different batches of BB when prepared according to a standardized recipe. If the intake of collagen precursors is proven to support the synthesis of new collagen in vivo, it is unlikely that BB can provide a consistently reliable source of key amino acids. Research on the provision of key amino acids from dietary sources should continue to focus on the standard sources currently being researched.

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Rebekah D. Alcock, Gregory C. Shaw, Nicolin Tee, Marijke Welvaert, and Louise M. Burke

The urinary excretion of hydroxyproline (Hyp), abundant in collagen protein, may serve as a biomarker of habitual collagen intake, assisting with investigations of current interest in the role of dietary collagen intake in supporting the synthesis of collagenous body tissues. This study investigated the time course of urinary Hyp excretion in “free-living,” healthy, active males following the ingestion of a standardized bolus (20 g) of collagenous (gelatin and a hydrolyzed collagen powder) and dairy (calcium caseinate and hydrolyzed casein) proteins. The excretion of Hyp was assessed over a 24-hr period, separated into three collection periods: 0–6, 6–12, and 12–24 hr. Hyp was elevated for 0–6 hr after the consumption of collagen-containing supplements (gelatin 31.3 ± 8.8 mmol/mol and hydrolyzed collagen 33.7 ± 22.0 mmol/mol vs. baseline: gelatin 2.4 ± 1.7 mmol/mol and hydrolyzed collagen 2.8 ± 1.5 mmol/mol; p < .05), but not for the dairy protein supplements (calcium caseinate 3.4 ± 1.7 mmol/mol and hydrolyzed casein 4.0 ± 3.7 mmol/mol; p > .05). Therefore, urinary Hyp reflects an acute intake of collagenous protein, but is not suitable as a biomarker for quantifying habitual collagen intake, provided through regular dietary practices in “free-living,” healthy, active males.

Open access

Ricardo J.S. Costa, Kayla Henningsen, Stephanie K. Gaskell, Rebekah Alcock, Alice Mika, Christopher Rauch, Samuel N. Cheuvront, Phil Blazy, and Robert Kenefick

The study aimed to determine the effects of two differing amino acid beverage interventions on biomarkers of intestinal epithelial integrity and systemic inflammation in response to an exertional-heat stress challenge. One week after the initial assessment, participants (n = 20) were randomly allocated to complete two exertional-heat stress trials, with at least 1 week washout. Trials included a water control trial (CON), and one of two possible amino acid beverage intervention trials (VS001 or VS006). On VS001 (4.5 g/L) and VS006 (6.4 g/L), participants were asked to consume two 237-ml prefabricated doses daily for 7 days before the exertional-heat stress, and one 237-ml dose immediately before, and every 20 min during 2-hr running at 60% maximal oxygen uptake in 35 °C ambient conditions. A water volume equivalent was provided on CON. Whole blood samples were collected pre-, immediately post-, 1 and 2 hr postexercise, and analyzed for plasma concentrations of cortisol, intestinal fatty acid protein, soluble CD14, and immunoglobulin M (IgM) by ELISA, and systemic inflammatory cytokines by multiplex. Preexercise resting biomarker concentrations for all variables did not significantly differ between trials (p > .05). A lower response magnitude for intestinal fatty acid protein (mean [95% CI]: 249 [60, 437] pg/ml, 900 [464, 1,336] pg/ml), soluble CD14 (−93 [−458, 272] ng/ml, 12 [−174, 197] ng/ml), and IgM (−6.5 [−23.0, 9.9] MMU/ml, −10.4 [−16.2, 4.7] MMU/ml) were observed on VS001 and V006 compared with CON (p < .05), respectively. Systemic inflammatory response profile was lower on VS001, but not VS006, versus CON (p < .05). Total gastrointestinal symptoms did not significantly differ between trials. Amino acid beverages’ consumption (i.e., 4.5–6.4 g/L), twice daily for 7 days, immediately before, and during exertional-heat stress ameliorated intestinal epithelial integrity and systemic inflammatory perturbations associated with exercising in the heat, but without exacerbating gastrointestinal symptoms.