Presence and formation of cobalamin analogues in multivitamin-mineral pills.

Abstract

A B S T R A C T Because the origin of cobalamin (vitamin B12) analogues in animal chows and animal and human blood and tissues is unknown, we investigated the possibility that multivitamin interactions might convert cobalamin to cobalamin analogues. We homogenized three popular multivitamin-mineral pills in water, incubated them at 37°C for 2 h, and isolated the cobalamin. Using paper chromatography we observed that 20-90% of the cobalamin was present as cobalamin analogues. Studies using cobalamin showed that these analogues were formed due to the concerted action of vitamin C, thiamine, and copper on CN-cobalamin. These cobalamin analogues are absorbed from the gastrointestinal tract of mice and either fail to stimulate or actually inhibit cobalamindependent enzymes when injected parenterally.We conclude that CN-cobalamin can be converted to potentially harmful cobalamin analogues by multivitamin-mineral interactions and that these interactions may be responsible for the presence of cobalamin analogues in animal chows and animal and human blood and tissues.

Effect of the cobalt‐N coordination on the cobamide recognition by the human vitamin B12 binding proteins intrinsic factor, transcobalamin and haptocorrin

“…Significant amounts of the total corrinoids in human serum [23] are cobalamin analogues with unidentified functions. Three reasons have been considered for the occurrence of the corrinoid analogues in the plasma: (I) bacterial biosynthesis and subsequent transfer into the plasma, (11) modification and degradation of vitamin B12 by chemicals, or (111) extraction and isolation artifacts [ S , 241.…”

Inhibition of cobalamin-dependent enzymes by cobalamin analogues in rats.

“…Previous investigations have shown that there are a variety of mechanisms which appear to prevent the absorption and tissue dissemination of certain of these cbl analogues (16)(17)(18). Previous studies have also shown that there are cbl analogues ofunknown structure in human serum (19), animal tissues (20), and foodstuffs and vitamin supplements (21), though their effects on cbl metabolism are largely unknown.…”

Current aspects of treatment of diabetic polyneuropathy in patients with diabetes

“…Кроме того, доказана их клиническая эффективность при лечении болей при диабетической полинейропатии, и они широко используются с этой целью в некоторых странах, включая Россию, Германию и Японию. Проведено несколько ран-домизированных двойных слепых плацебо-контролируе-мых исследований эффективности бенфотиамина или его комбинаций с витаминами В6 и B12, показавших досто-верное уменьшение болей и парестезии, снижение поро-га вибрационной чувствительности и улучшение ЭМГ-показателей функционального состояния нерва [8].…”