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

Alcock RD, Shaw GC, Tee N, Burke LM · Frontiers in Nutrition

Collagen proteins produced far higher plasma glycine peaks than dairy (683 vs 260 umol/L, p < .0001); dairy gave higher leucine (267 vs 189 umol/L, p < .04). The bone broth arm matched the collagen supplements on glycine (666 vs 646-747 umol/L) and on proline, and gave the highest total amino-acid area under the curve of any arm (91,029 umol/L/180 min) — significantly higher than both dairy proteins but not significantly different from any collagen supplement. It was the slowest to peak: glycine at 88 minutes against 48 for the collagen peptides, still elevated when the window closed. It also carried the most protein by a wide margin, which is why the authors say the broth's bioavailability cannot fairly be compared with the rest.

Population

Healthy recreationally active males (30 +/- 5 years); randomized counter-balanced crossover, 180-min serial blood sampling, >=48 h between trials

Intervention

20 g servings of various dairy and collagen proteins, or a 300 mL serve of chef-made bone broth, after an overnight fast

Comparator

Six arms compared against each other: caseinate, hydrolysed casein, gelatin, collagen peptides, liquid collagen, bone broth

Limitations

Small (n=15) acute pharmacokinetic study in healthy young men, with surrogate endpoints only. The broth was a single chef-prepared batch whose protein content the authors did not measure in advance and afterwards found 'considerably higher than expected' (52.2 g per 300 mL, against the 20 g every supplement arm was standardised to) — it represents the high end of stock composition, not a typical one, and the authors say the discovery 'makes it difficult to compare the bioavailability based on their actual protein intake'. Funded through the Australian Catholic University by a Super Rugby team; no commercial relationships declared, though one of the tested products is a collagen manufacturer's.