VITAMIN B12 AND HOMOCYSTEINE LEVELS IN PATIENTS WITH NAFLD: A SYSTEMATIC REVIEW AND METANALYSIS

ABSTRACT BACKGROUND: The vitamin B12 absorption can be affected in patients with nonalcoholic fatty liver disease (NAFLD), and low serum vitamin B12 levels has been related to the high homocysteine (HCY) levels and to the degree of NAFLD. OBJECTIVE: To carry out a systematic review and metanalysis of serum vitamin B12 and HCY levels in patients with NAFLD. METHODS: Original studies including serum vitamin B12 and HCY levels in humans with NAFLD were included. The searches were performed in four databases. RESULTS: 159 studies were identified, and after excluding the duplicates and non-eligible titles, eight original articles were included. Six out of eight showed higher B12 levels in NAFLD patients (404.9±136.2 pg/mL in relation to controls 353.91±117.3 pg/mL). Seven of the eight studies also showed higher HCY levels in NAFLD patients (14.2±3.44 umol/L in relation to controls 11.05±3.6 umol/L). The results for serum vitamin B12 and HCY levels were submitted to metanalysis, showing no difference in the vitamin B12 levels between patients with NAFLD and controls. However, the levels of Hcy were higher in NAFLD patients than in controls. CONCLUSION: There was no relashionship between the vitamin B12 levels and NAFLD. The levels of HCY were significantly higher in patients with NAFLD, suggesting this could be a potential marker for liver damage.

Vitamin B12 Absorption as Measured by Total B12 and Holo-TC Following A Single Oral Dose of Multivitamin in Healthy Adults

Objectives Measure total B12 and holotranscobalamin (Holo-TC) concentrations in serum to show vitamin B12 absorption following single oral doses of multivitamin (MVI) gummy and tablet. Methods This crossover clinical trial involved healthy adults randomized to either gummy or tablet multivitamins (MVI) containing vitamin B12 (60.8 mcg in gummy and 91.8 mcg in tablet) as cyanocobalamin in a single dose in Phase 1 with serial blood samples collected at pre-dose and at 0.5-, 1-, 2-, 4-, 6-, 8-, 9-, 10-, 24-, and 48-hrs after dosing, followed by a 2-week washout period. In Phase 2, participants then crossed over to receive MVI in the form not previously given, with blood draws at the same timepoints. Serum samples were measured for total B12 (n = 19) using an electrochemiluminescence immunoassay (ECLIA) and for Holo-TC (n = 14) using commercial Holo-TC ELISA kit. Measurements from groups of time points were averaged to estimate pre-absorptive (0 to 2 hours) and absorptive (6 to 10 hours) concentrations of total B12 and Holo-TC for each subject. The difference between pre-absorptive and absorptive concentrations for both analytes was calculated to estimate newly absorbed vitamin B12. Results Mean increases of about 15% in serum Holo-TC in absorptive phase over the pre-absorptive phase were observed for both the gummies and the tablets, which are statistically significant (p < 0.001). These changes were similar to those observed for total B12. There was no significant difference in mean increases between the gummies and the tablets in both total B12 and Holo-TC. These results support the conclusion that the observed increases in total B12 and Holo-TC were the result of intestinal absorption following the single oral dose. Conclusions Overall, under the conditions of this study, both gummy and tablet multivitamins showed similar absorption of vitamin B12, whether assessed by total B12 or holo-TC measurement. Funding Sources Church & Dwight Co. Inc.

Deficiency anaemias

This chapter addresses the diagnosis, investigation, and management of anaemia due to a deficiency in iron, vitamin B12, or folate. Erythropoiesis requires an adequate supply of iron for haem formation, as well as vitamin B12 and folic acid (folate) to support high levels of DNA synthesis, and a lack of any of these will result in anaemia. Iron-deficient anaemias are typically microcytic, while a deficiency in vitamin B12 or folate results in megaloblastic haemopoiesis and a macrocytic anaemia. Iron deficiency results from poor dietary iron intake, poor absorption, increased demands, blood loss, or combinations of these. The usual cause of severe vitamin B12 deficiency in Western countries is an autoimmune atrophic gastritis, in which there is a loss of gastric parietal cell numbers and an absence of intrinsic factor production, which effectively prevents vitamin B12 absorption. This is the classical pernicious anaemia, and it is often seen in association with other autoimmune disorders. Folate deficiency may result from poor diet, malabsorption, or when demand for folate is increased, for example, during pregnancy, or with increased haemopoiesis in haemolytic anaemias or myeloproliferative disorders.