Tier 3 — preclinical

Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates

Koji Iwai, Takanori Hasegawa, Yasuki Taguchi, Fumiki Morimatsu, Kenji Sato, Yasushi Nakamura, Akane Higashi, Yasuhiro Kido, Yukihiro Nakabo, Kozo Ohtsuki
Journal of Agricultural and Food Chemistry 2005 53(16):6531–6536

Bibliography

PubMed
PMID 16076145
DOI
10.1021/jf050206p
Funding
No external grant funding statement disclosed in the paper. Acknowledgment: "We thank Nitta gelatin for providing porcine type I gelatin hydrolysate (SCP-5000)."
Competing interests
The paper does not provide a formal competing-interests declaration. Takanori Hasegawa, Yasuki Taguchi and Fumiki Morimatsu were affiliated with the Research and Development Center of Nippon Meat Packers, and the authors acknowledged Nitta Gelatin for providing the porcine type I gelatin hydrolysate. These commercial affiliations and product supply are relevant context but should not be described as a declared conflict.

Study snapshot

DesignOpen-label, single-dose, two-experiment human bioavailability study
ModelHealthy Japanese adult volunteers
Sample12 total (Experiment 1: n=5 aged 21–39, 45–80 kg; Experiment 2: n=7 males aged 25–37, 47–67 kg)
InterventionSingle oral dose of gelatin hydrolysate after 12 h fast. Exp 1: 9.4 g porcine skin type I hydrolysate (SCP-5000). Exp 2: 23 g chicken feet type I (C-LAP) or 11 g chicken cartilage type II (C-mucolla) per 60 kg body weight.
DurationSingle-dose kinetics. Experiment 1: baseline and 15, 30, 60 and 180 min after porcine type I hydrolysate. Experiment 2: serial sampling at suitable intervals after chicken type I or type II hydrolysate; peptide identification was performed at 60 min for type I and 120 min for type II, and one subject was additionally sampled at 12 and 24 h.
EndpointsPeptide-form hydroxyproline plasma concentration and time course; Identification of collagen-derived peptide sequences by RP-HPLC and Edman degradation; Semi-quantitative peptide composition per source; In vitro Pro-Hyp digestibility by human serum peptidase

What the study showed, in plain terms

This 2005 human bioavailability study asked whether small collagen-derived peptides survive digestion and appear intact in the bloodstream after oral gelatin hydrolysate. Twelve healthy volunteers participated across two small single-dose experiments using porcine type I, chicken type I, or chicken type II gelatin hydrolysates.

Collagen-derived peptides appeared in plasma after ingestion, but the timing depended on the source and experiment. In the porcine experiment, peptide-form hydroxyproline peaked about 30–60 minutes after dosing. In the chicken-source experiment, the reported maxima occurred at about 60 minutes for type I and 120 minutes for type II. Pro-Hyp was the dominant circulating peptide, with several additional hydroxyproline-containing di- and tripeptides identified.

The study is foundational evidence that at least some collagen peptides can survive gastrointestinal digestion and reach human blood intact. It is a bioavailability experiment, not an efficacy trial: it did not test whether the circulating peptides reached human skin, joints or bone, nor whether they improved any clinical outcome.

Key findings

  • In Experiment 1 with porcine type I gelatin hydrolysate, peptide-form hydroxyproline reached its maximum plasma concentration about 30–60 minutes after ingestion.
  • In Experiment 2, the reported maximum peptide-form hydroxyproline concentration occurred at about 60 minutes after chicken type I gelatin hydrolysate and about 120 minutes after chicken type II gelatin hydrolysate, showing source-dependent kinetics.
  • Pro-Hyp was the dominant identified circulating collagen-derived peptide: approximately 95% of detected peptides after porcine type I, 92% after chicken type I, and about 70% after chicken type II hydrolysate.
  • Minor identified peptides included Ala-Hyp-Gly, Pro-Hyp-Gly, Ile-Hyp, Leu-Hyp and Phe-Hyp; after chicken type II hydrolysate, Pro-Hyp-Gly represented about 19% of the detected peptide fraction.
  • Pro-Hyp was relatively resistant to human serum peptidase in vitro, helping explain its persistence in circulation.
  • In the one participant followed to later time points, peptide-form hydroxyproline had returned to baseline by 12 hours.

What this study can and cannot tell us

  • Very small sample sizes (n=5 in Experiment 1, n=7 in Experiment 2) — plasma peptide levels showed wide individual variation, and no statistical inference about population means is warranted.
  • Open-label with no placebo or non-collagen protein control. The paper is descriptive of what appears in blood after collagen ingestion, not comparative.
  • Single-dose only. No data on whether peptide plasma levels rise, plateau or fall with repeated daily ingestion.
  • All subjects were Japanese. No inference about inter-ethnic differences in gut peptide transporter expression or peptide absorption kinetics.
  • Substantial industry involvement — three co-authors were employed by Nippon Meat Packers, a commercial gelatin hydrolysate manufacturer, and the porcine hydrolysate was gifted by Nitta Gelatin. No competing interests statement is provided.
  • Peptide identification was by semi-quantitative Edman sequencing of RP-HPLC peaks. Absolute quantification requires stable-isotope-labelled internal standards, which were not used.
  • The study establishes that collagen-derived peptides reach the bloodstream. It does not measure whether they reach skin, joint or bone tissue, and does not measure any biological effect at any site.

Citation network

Articles citing this research paper

12 articles

Biohack Blueprint analyses that reference this study in their evidence base.

Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology