T FIAT VITAMIN B12 IN SERUM is l)ound to protein14 has been known since shortly after the isolation of the vitamin. Endogenous vitamin B12 (which may be mainly methyl-Bi2) is bound primarily to an a1-globulin 2.6-10 hut vitamin B12 added to serum in vitro hinds primarily to -globuun (presumably because B12-binding a-globulin is normally almost saturated with endogenous vitamin B12).61#{176} hal...

Complete B12 derivatives are natural "molecular switches" as a result of the coordinative switch ("base on" or "base off") of the natural nucleotide base. Certain predesigned B12-nucleotide conjugates were shown recently to behave as "retro riboswitches", in which the nucleotide environment modified the equilibrium between these two isomeric B12 structures. In contrast, the "reverse" situation ...

BACKGROUND There is a growing focus on nutritional therapy for Alzheimer's disease (AD), and controversy exists regarding the association between AD and homocysteine (Hcy), vitamin B12, and folate levels. OBJECTIVE The present study evaluated the association between AD and the combined levels of Hcy, vitamin B12, and folate. METHODS This case-control study consisted of 115 patients with AD ...

Substantial amounts of vitamin B12 were found in some edible algae (green and purple lavers) and algal health food (chlorella and spirulina tablets) using the Lactobacillus delbrueckii subsp. lactis ATCC7830 microbiological assay method. Corrinoid-compounds were purified and characterized from these algae to clarify the chemical properties and bioavailability of the algal vitamin B12. True vita...

Vitamin B12 maintains normal folate metabolism which is essential for cell multiplication during pregnancy. No good data are available on what constitutes vitamin B12 deficiency in pregnancy, nevertheless vitamin B12 deficiency is frequently reported in pregnancy due to inadequate dietary intake of vitamin B12 and a physiological decline of maternal vitamin B12 concentrations. This decline can ...

In cobaiamin deficiency, inadequate DNA-thymine synthesis appears to resuit from decreased conversion of N5methyltetrahydrofolic acid to tetrahydrofo ic acid (THE). The N5-methyl THE conversion catalyzed by N5methyl THF-homocysteine methyltransferase requires a cobalamin coenzyme, presumed to be methylcobalamin (methyl-B12). In support of the above, in B12-deficient marrow cultures, methyl-B12 ...

Vitamin B12 (B12) adequacy during pregnancy is crucial for maternal health and optimal fetal development; however, suboptimal B12 status has been reported in pregnant Canadian women. Methylmalonic acid (MMA) is a sensitive indicator of B12 status. Since few studies have measured MMA during pregnancy in Canadian women, the objective of this study was to evaluate B12 status in pregnant women livi...

The usual dietary sources of vitamin B12 are animal foods, meat, milk, egg, fish, and shellfish. As the intrinsic factor-mediated intestinal absorption system is estimated to be saturated at about 1.5–2.0 lg per meal under physiologic conditions, vitamin B12 bioavailability significantly decreases with increasing intake of vitamin B12 per meal. The bioavailability of vitamin B12 in healthy huma...

Dietary supplements and functional foods are becoming increasingly popular complements to regular diets. A recurring ingredient is the essential cofactor vitamin B12 (B12). Microalgae are making their way into the dietary supplement and functional food market but do not produce B12, and their B12 content is very variable. In this study, the suitability of using the human B12-binding protein int...