Vitamin B12 (cobalamin, Cbl) is an essential nutrient in human metabolism. Genetic diseases of vitamin B12 utilisation constitute an important fraction of inherited newborn disease. Functionally, B12 is the cofactor for methionine synthase and methylmalonyl CoA mutase. To function as a cofactor, B12 must be metabolised through a complex pathway that modifies its structure and takes it through s...

Several observations suggest that the absorption of vitamin B12 may be inhibited by bacteria. Both in experimental animals and in patients with blind loops, strictures, or fistulae involving the small intestine, heavy growths of bacteria have been found in areas of the bowel which are normally sterile (Seyderhelm, Lehmann, and Wichels, 1924; Doig and Girdwood, 1960). In patients with such lesio...

INTRODUCTION Although consensus guidelines recommend checking serum B12 in patients with dementia, clinicians are often faced with various questions: (1) Which patients should be tested? (2) What test should be ordered? (3) How are inferences made from such testing? (4) In addition to serum B12, should other tests be ordered? (5) Is B12 deficiency compatible with dementia of the Alzheimer's typ...

By ROBERT S. MENDELSOIIN, DONALD M. WATKIN, ANN P. HORBETr AND J OHN L. FAHEY R ECENT STUDIES have demonstrated that virtually all the vitamin B12 in normal serum is bound to serum proteins.1 In chronic myelocytic leukemia tile serum B12 concentration may be increased from 2 to 30 times normal levels.24 At these increased levels, all or almost all of the B12 is protein-bound. However, normal se...

OBJECTIVE The current meta-analysis evaluated the association between vitamin B12 intake and blood vitamin B12 level and colorectal cancer (CRC) risk. DESIGN The PubMed and EMBASE databases were searched. A dose-response analysis was performed with generalized least squares regression, with the relative risk (RR) and 95 % CI as effect values. SETTING The meta-analysis included seventeen stu...

BACKGROUND Cobalamin deficiency is responsible for hematological, neurological, neurocognitive, and neuropsychiatric impairments and is a risk factor for cardiovascular diseases, particularly in the elderly people. METHODS In order to determine B12 status in old inpatients, a total number of 14,904 hospitalized patients in whom B12 measurements were performed in five hospitals in the Paris me...

Metformin causing vitamin B12 (B12) deficiency has become a traditional myth in medical literature (1,2). But what evidence do we have? The possibility to measure holotranscobalamin (active B12) and the metabolic marker, methylmalonic acid (MMA), has changed the practice of diagnosing B12 deficiency in recent years. We have learned that not all low plasma B12 means a “deficiency” and not all hi...

The understanding and control of nanoparticle transport into and through cellular compartments is central to biomedical applications of nanotechnology. Here, it is shown that the transport pathway of 50 nm polystyrene nanoparticles decorated with vitamin B12 in epithelial cells is different compared to both soluble B12 ligand and unmodified nanoparticles, and this is not attributable to B12 rec...

Treatment of B12 deficiency is important to prevent progressive neurological and/or hematologic disease but requires a secure diagnosis. The aim of this study was to evaluate second line tests of B12 status as prognostic indicators of a hematologic response to vitamin B12 therapy. Forty-nine patients referred with low, serum vitamin B12 concentrations were treated with intramuscular B12 and re-...