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

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 (CH3-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-12更多