TY - JOUR
T1 - Absorption and retention of free and milk protein-bound cyano- and hydroxocobalamins
T2 - An experimental study in rats
AU - Kornerup, Linda Skibsted
AU - Juul, Christian Bredgaard
AU - Fedosov, Sergey
AU - Heegaard, Christian Würtz
AU - Greibe, Eva
AU - Nexø, Ebba
N1 - Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.
PY - 2016/7
Y1 - 2016/7
N2 - Introduction
Cobalamin/Vitamin B12 (Cbl) is an essential vitamin, supplied mainly as hydroxocobalamin (OHCbl) by animal products, including cows' milk. Cyanocobalamin (CNCbl) is the usual form in vitamin pills. The aim was to explore absorption and tissue accumulation of two Cbl forms, administered alone or bound to milk protein.
Materials and methods
We synthesized labeled OH[57Co]Cbl from commercially available CN[57Co]Cbl. Recombinant bovine transcobalamin (rbTC) was produced in yeast and skimmed milk obtained off the shelf. Male Wistar rats (250–300 g) received labeled Cbl by gastric gavage. First, we administered CN[57Co]Cbl, free or rbTC-bound (n = 15 in each group). Rats were sacrificed after two, 24, and 48 h. In the following studies, rats were sacrificed after 24 h. We compared absorption of free or rbTC-bound CN[57Co]Cbl added to cows' milk and analogous absorption of OH[57Co]Cbl, free or rbTC-bound, to absorption of free CN[57Co]Cbl, (n = 10 in each group). Blood, tissues, 24-h urine and feces were collected. Labeled Cbl was measured using a gamma counter. Results are expressed as percentage of administered dose.
Results
Absorptions of CNCbl and OHCbl were neither influenced by rbTC-binding nor administration in milk. Absorption increased in the first 24 h with no further tissue accumulation during the subsequent 24 h. Accumulation of free CNCbl and (OHCbl) was 1.4, (4.1) (liver); 20.2, (16.4) (kidney); and 0.05, (0.02) (plasma)% 24 h after administration. Total organ accumulations were 21.6, (20.5)%. While total accumulations of CNCbl and OHCbl were equal, distributions between liver, kidney, and plasma showed significant differences (p < 0.0001; p = 0.01; p < 0.0001).
Conclusions
Cbl added to milk (spiked with rbTC) has high bioavailability matching that of free Cbl. OHCbl and CNCbl are absorbed equally well, but much more OHCbl accumulated in the liver. Benefits of oral supplementation with OHCbl compared to CNCbl should be investigated.
AB - Introduction
Cobalamin/Vitamin B12 (Cbl) is an essential vitamin, supplied mainly as hydroxocobalamin (OHCbl) by animal products, including cows' milk. Cyanocobalamin (CNCbl) is the usual form in vitamin pills. The aim was to explore absorption and tissue accumulation of two Cbl forms, administered alone or bound to milk protein.
Materials and methods
We synthesized labeled OH[57Co]Cbl from commercially available CN[57Co]Cbl. Recombinant bovine transcobalamin (rbTC) was produced in yeast and skimmed milk obtained off the shelf. Male Wistar rats (250–300 g) received labeled Cbl by gastric gavage. First, we administered CN[57Co]Cbl, free or rbTC-bound (n = 15 in each group). Rats were sacrificed after two, 24, and 48 h. In the following studies, rats were sacrificed after 24 h. We compared absorption of free or rbTC-bound CN[57Co]Cbl added to cows' milk and analogous absorption of OH[57Co]Cbl, free or rbTC-bound, to absorption of free CN[57Co]Cbl, (n = 10 in each group). Blood, tissues, 24-h urine and feces were collected. Labeled Cbl was measured using a gamma counter. Results are expressed as percentage of administered dose.
Results
Absorptions of CNCbl and OHCbl were neither influenced by rbTC-binding nor administration in milk. Absorption increased in the first 24 h with no further tissue accumulation during the subsequent 24 h. Accumulation of free CNCbl and (OHCbl) was 1.4, (4.1) (liver); 20.2, (16.4) (kidney); and 0.05, (0.02) (plasma)% 24 h after administration. Total organ accumulations were 21.6, (20.5)%. While total accumulations of CNCbl and OHCbl were equal, distributions between liver, kidney, and plasma showed significant differences (p < 0.0001; p = 0.01; p < 0.0001).
Conclusions
Cbl added to milk (spiked with rbTC) has high bioavailability matching that of free Cbl. OHCbl and CNCbl are absorbed equally well, but much more OHCbl accumulated in the liver. Benefits of oral supplementation with OHCbl compared to CNCbl should be investigated.
KW - Cobalamin
KW - Cyanocobalamin
KW - Hydroxocobalamin
KW - Intestinal absorption
KW - Rat
KW - Transcobalamin
KW - Vitamin B12
KW - Rats, Wistar
KW - Transcobalamins/chemistry
KW - Rats
KW - Male
KW - Vitamin B 12/chemistry
KW - Recombinant Proteins/chemistry
KW - Animals
KW - Adsorption
KW - Cattle
KW - Milk Proteins/chemistry
U2 - 10.1016/j.biochi.2015.11.024
DO - 10.1016/j.biochi.2015.11.024
M3 - Journal article
C2 - 26626348
SN - 0300-9084
VL - 126
SP - 57
EP - 62
JO - Biochimie
JF - Biochimie
ER -