Role of Third Serum Vitamin B12 Binding Protein in Vitamin B12 TransportBr Med J 1972; 2 doi: https://doi.org/10.1136/bmj.2.5811.441 (Published 20 May 1972) Cite this as: Br Med J 1972;2:441
- I. Chanarin,
- J. M. England,
- K. L. Rowe,
- J. A. Stacey
A third vitamin B12 binding protein present in normal serum has been shown to participate in transport of labelled vitamin B12 absorbed from the gut. All three vitamin B12 binding proteins in serum were labelled at the same time after oral administration of vitamin B12, implying that “free” vitamin B12 reached the portal blood from the gut mucosa.