Human uptake and incorporation of an immunogenic nonhuman dietary sialic acid.
Level 4 - case-series / case-control
Mechanistic laboratory study combining in vitro assays, human tissue series, and an uncontrolled human volunteer feeding experiment.
PubMed 14523234 · doi:10.1073/pnas.2131556100
What was done
Researchers investigated the presence, metabolic incorporation, and immune response to the nonhuman sialic acid N-glycolylneuraminic acid (Neu5Gc) in humans. Using a newly generated specific antibody confirmed by mass spectrometry, they analyzed human fetal tissues, normal adult tissues, and breast carcinomas. They measured Neu5Gc content across different foods, tested metabolic uptake in cultured human cells, tracked urinary elimination and glycoprotein incorporation after oral Neu5Gc ingestion in healthy human volunteers, and measured circulating anti-Neu5Gc antibodies in human sera.
What was found
Neu5Gc was present in human fetal, normal adult, and breast carcinoma tissues, predominantly in secretory epithelia and blood vessels. Cultured human cells incorporated Neu5Gc into endogenous glycoproteins. Ingested Neu5Gc was absorbed by human volunteers, excreted in part through urine, and incorporated in small amounts into newly synthesized glycoproteins. Neu5Gc was enriched in red meats, common in milk products, and rare in poultry and fish. Normal humans exhibited variable circulating IgA, IgM, and IgG antibodies against Neu5Gc, with peak levels comparable to anti-alpha-galactose antibodies. No specific quantitative values or sample sizes were reported in the abstract.
Why it matters
This study shows that humans absorb and metabolically incorporate a dietary carbohydrate found in red meat and dairy despite mounting xenoreactive antibodies against it. This establishes a direct biochemical mechanism potentially linking mammalian food consumption to human immune and inflammatory processes.
Limits
The abstract does not state the number of human participants or tissue samples evaluated. No exact numerical measurements, statistical analyses, or control comparison details are provided. Clinical disease outcomes were not directly evaluated.
Cited by
- supports Consuming beef, lamb, pork, and milk containing Neu5Gc causes humans to produce aggressive antibodies against Neu5Gc and incorporate it into tissue glycocalyces, displacing Neu5Ac.