The tissue profile of metabolically active coenzyme forms of vitamin B12 differs in vitamin B12-depleted rats treated with hydroxo-B12 or cyano-B12

TY - JOUR

T1 - The tissue profile of metabolically active coenzyme forms of vitamin B12 differs in vitamin B12-depleted rats treated with hydroxo-B12 or cyano-B12

AU - Greibe, Eva

AU - Kornerup, Linda Skibsted

AU - Juul, Christian Bredgaard

AU - Fedosov, Sergey

AU - Heegaard, Christian Würtz

AU - Nexø, Ebba

PY - 2018/7/14

Y1 - 2018/7/14

N2 - Recent rat studies show different tissue distributions of vitamin B 12 (B 12), administered orally as hydroxo-B 12 (HO-B 12) (predominant in food) and cyano-B 12 (CN-B 12) (common in supplements). Here we examine male Wistar rats kept on a low-B 12 diet for 4 weeks followed by a 2-week period on diets with HO-B 12 (n 9) or CN-B 12 (n 9), or maintained on a low-B 12 diet (n 9). Plasma B 12 was analysed before, during and after the study. The content of B 12 and its variants (HO-B 12, glutathionyl-B 12, CN-B 12, 5′-deoxyadenosyl-B 12 (ADO-B 12), and methyl-B 12 (CH 3-B 12)) were assessed in the tissues at the end of the study. A period of 4 weeks on the low-B 12 diet reduced plasma B 12 by 58 % (from median 1323 (range 602-1791) to 562 (range 267-865) pmol/l, n 27). After 2 weeks on a high-B 12 diet (week 6 v. week 4), plasma B 12 increased by 68 % (HO-B 12) and 131 % (CN-B 12). Total B 12 in the tissues accumulated differently: HO-B 12>CN-B 12 (liver, spleen), HO-B 1212 (kidneys), and HO-B 12≈CN-B 12 (brain, heart). Notably, more than half of the administered CN-B 12 remained in this form in the kidneys, whereas HO-B 12 was largely converted to the bioactive ADO-B 12. Only <10 % of the other cofactor, CH 3-B 12, were found in the tissues. In conclusion, dietary CN-B 12 caused a higher increase in plasma and total kidney B 12 but provided less than half of the active coenzymes in comparison to dietary HO-B 12. These data argue that HO-B 12 may provide a better tissue supply of B 12 than CN-B 12, thereby underscoring the lack of a direct relation between plasma B 12 and tissue B 12.

AB - Recent rat studies show different tissue distributions of vitamin B 12 (B 12), administered orally as hydroxo-B 12 (HO-B 12) (predominant in food) and cyano-B 12 (CN-B 12) (common in supplements). Here we examine male Wistar rats kept on a low-B 12 diet for 4 weeks followed by a 2-week period on diets with HO-B 12 (n 9) or CN-B 12 (n 9), or maintained on a low-B 12 diet (n 9). Plasma B 12 was analysed before, during and after the study. The content of B 12 and its variants (HO-B 12, glutathionyl-B 12, CN-B 12, 5′-deoxyadenosyl-B 12 (ADO-B 12), and methyl-B 12 (CH 3-B 12)) were assessed in the tissues at the end of the study. A period of 4 weeks on the low-B 12 diet reduced plasma B 12 by 58 % (from median 1323 (range 602-1791) to 562 (range 267-865) pmol/l, n 27). After 2 weeks on a high-B 12 diet (week 6 v. week 4), plasma B 12 increased by 68 % (HO-B 12) and 131 % (CN-B 12). Total B 12 in the tissues accumulated differently: HO-B 12>CN-B 12 (liver, spleen), HO-B 1212 (kidneys), and HO-B 12≈CN-B 12 (brain, heart). Notably, more than half of the administered CN-B 12 remained in this form in the kidneys, whereas HO-B 12 was largely converted to the bioactive ADO-B 12. Only <10 % of the other cofactor, CH 3-B 12, were found in the tissues. In conclusion, dietary CN-B 12 caused a higher increase in plasma and total kidney B 12 but provided less than half of the active coenzymes in comparison to dietary HO-B 12. These data argue that HO-B 12 may provide a better tissue supply of B 12 than CN-B 12, thereby underscoring the lack of a direct relation between plasma B 12 and tissue B 12.

KW - ADO-B12 5'-deoxyadenosyl-B12

KW - Active coenzymes

KW - B12 vitamin B12

KW - CH3-B12 methyl-B12

KW - CN-B12 cyano-B12

KW - Cyanocobalamin

KW - Dietary vitamin B12

KW - GS-B12 glutathionyl-B12

KW - HO-B12 hydroxo-B12

KW - Hydroxocobalamin

KW - Tissue distribution

KW - Vitamin B12-depleted rats

UR - http://www.scopus.com/inward/record.url?scp=85049214058&partnerID=8YFLogxK

U2 - 10.1017/S000711451800123X

DO - 10.1017/S000711451800123X

M3 - Journal article

C2 - 29936920

SN - 0007-1145

VL - 120

SP - 49

EP - 56

JO - British Journal of Nutrition

JF - British Journal of Nutrition

IS - 1

ER -