Medical Issues, Pharmacology and Nutrient Interaction
Elizabeth Broad in Sports Nutrition for Paralympic Athletes, 2019
Antacids reduce and/or neutralise gastric acidity, making them useful medications for gastric reflux, indigestion and heartburn. Antacids have different classes (e.g., H2-antihistamines, proton pump inhibitors) with specific pharmacological mechanisms. However, independent of the pharmacological mechanism, vitamin B12 release from dietary proteins is decreased due to the lack of gastric acid, which may lead to a vitamin B12 undersupply with chronic use of antacids (Ruscin et al. 2002). Vitamin B12 plays a crucial role in the health of the body's nerve and blood cells, DNA synthesis and prevention of megaloblastic anaemia, which leads to weakness and fatigue (Office of Dietary Supplements 2011). The bioavailability of omeprazole, a proton pump inhibitor, seems to be increased by soybean administration, whereas esomeprazole, another proton pump inhibitor, showed a significantly decreased bioavailability when taken 15 minutes before eating a high-fat meal compared to the fasted state (Singh and Asad 2010; Sostek et al. 2007).
Visual-Evoked Potential in Neuro-Ophthalmology
Vivek Lal in A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Vitamin B12 is a common cause of myeloneuropathy and occasionally cognitive and behavioral change. B12 deficiency occurs in the patients who are unable to absorb it because of gastrointestinal disease, intrinsic factor deficiency, and widely variety of genetic and/acquired causes. Low vitamin B12 level is associated with megaloblastic anemia, involvement of posterior and lateral column of spinal cord and peripheral nerve resulting in subacute combined degeneration of the spinal cord (SACD). Vitamin B12 deficiencies usually manifest with sensory ataxia (distal paresthesia, joint position, and vibration sense impairment), spasticity and weakness, rarely optic neuropathy and may be the presenting sign of pernicious anemia [29]. Vitamin B12 deficiency results in bilateral prolongation of P100 latency, but the abnormality is generally asymptomatic. Visual acuity, field of vision, and color vision testing are normal. In a study on 17 patients with B12 deficiency neurologic syndrome, P100 latency was prolonged in 10 patients (17 eyes). There was no visual symptom and vision testing was also normal. After 6 months of treatment P100 latency improved in all except four eyes (Figure 3B.5). VEP changes were related to duration of illness [30].
Personalization of Nutrition Advice
David Heber, Zhaoping Li in Primary Care Nutrition, 2017
Vitamin B12, also called cyanocobalamin, is needed to make red blood cells and is necessary for the synthesis of nerve sheaths, fatty acids, and DNA. Since this vitamin is stored in the liver, nutritional deficiency usually takes years to develop. It is much more common to see metabolic deficiencies. Most commonly, an anemia due to B12 deficiency results from an autoimmune disease called pernicious anemia, in which the parietal cells in the stomach that make a binding protein (intrinsic factor) necessary for B12 absorption are destroyed (Seetharam and Alpers 1982). The healthy individuals most at risk of a dietary vitamin B12 deficiency are vegetarians, since there is no B12 in any plant product. There is also a decreased capability for absorption of vitamin B12 in the elderly due to decreased gastric acid secretion (Carmel 1997).
Relationships between depression and food intake in climacteric women
Published in Climacteric, 2020
C. M. Oldra, D. M. Benvegnú, D. R. P. Silva, G. W. Wendt, A. P. Vieira
Nguyen et al.37 investigated the relationship between depression and vitamin intake among older Japanese women, finding significant associations between low vitamin C, vitamin D, and vitamin B12 intake with depressive symptoms. These results are similar to those reported in the present study (see Tables 2 and 3). There are several mechanisms and explanations for linking these vitamins with the presence of depressive symptoms. Firstly, vitamin C, also known as ascorbic acid, is known for its important antioxidant effect. It is water-soluble and contributes to the synthesis of dopamine, norepinephrine, and (probably) serotonin. Not surprisingly, vitamin C deficiency has been thought to contribute to the onset of depressive symptoms40. Research has also been conducted in respect to vitamin D, a fat-soluble type of vitamin. Secondly, several brain regions contain vitamin D, vitamin D receptors, and associated enzymes (CYP 24A1, CYP 27B1), highlighting its importance in a variety of brain processes, such as neuroprotection, neuroimmunomodulation, brain development, and regular functioning41. Subsequently, vitamin B12 (or cobalamin) is a water-soluble vitamin responsible for maintaining red blood cells and the metabolism within the nervous system. Finally, studies have investigated the association between vitamin B12 and depression, yet the mechanisms possibly underpinning these links are not fully established42.
Serum Levels of Thyroid Hormone, Vitamin B12, Vitamin D3, Folic Acid, and Ferritin in Chalazion
Published in Ocular Immunology and Inflammation, 2022
Cagri Ilhan
Vitamin B12 is a water-soluble vitamin that is very important for the proper function of the human body. The main rationale to evaluate vitamin B12 levels in this study is to understand whether there is vitamin B12 level alteration in the chalazion pathogenesis, which is a lipogranulomatous inflammation. There is limited evidence of the presence of a direct association between vitamin B12 level and inflammation. Al-Daghri et al.18 reported a significant negative correlation between vitamin B12 level and tumor necrosis factor-α (TNF-α), while Young et al.19 reported a similar relationship between vitamin B12 level and C-reactive protein (CRP) for some races in their large population-based study. Some experimental animal studies showed that vitamin B12 deficiency triggers proinflammatory pathways through interleukin-1β (IL-1β), interleukin-10 (IL-10), and monocyte chemoattractant protein-1 (MCP-1).20 Nonetheless, there is not a consensus as to how vitamin B12 deficiency can be a reason for inflammation in human body and to what degree of, if any exists.
Fooled by the fragments: vitamin B12 deficiency masquerading as thrombotic thrombocytopenic purpura
Published in Journal of Community Hospital Internal Medicine Perspectives, 2021
Pegah Jahangiri, Rachel Hicks, Prabjot K. Batth, Christopher J. Haas
Vitamin B12 is a water-soluble vitamin with an essential role in DNA synthesis, hematopoiesis, and myelination. Vitamin B12 is a necessary cofactor for the conversion of methylmalonyl coenzyme A to succinyl coenzyme A via methylmalonyl coenzyme A mutase (Figure 2), enabling the breakdown of odd-chained fatty acids and some amino acids. It is also a required cofactor for methionine synthase, which catalyzes the conversion of homocysteine to methionine, ultimately allowing for the generation of tetrahydrofolate, a biologically active form of folate needed in DNA synthesis (Figure 2). Insufficient levels of vitamin B12 lead to reduced function of methylmalonyl coenzyme A mutase and methionine synthase, with a resultant accumulation of the precursors methylmalonyl coenzyme A and homocysteine, respectively. Classically, vitamin B12 deficiency manifests as a macrocytic, megaloblastic anemia and in severe cases, subacute combined degeneration of the posterior columns of the spinal cord. In rare cases, severe vitamin B12 deficiency can present as a pseudo-microangiopathic hemolytic anemia/TTP, characterized by thrombocytopenia and hemolytic anemia (i.e., elevated LDH, low haptoglobin, hyperbilirubinemia, and schistocytes). In contrast to classic microangiopathic hemolytic anemia/TTP, vitamin B12-related pseudo-TTP presents as a macrocytic, megaloblastic anemia with reticulocyte hypoproliferation, elevated levels of homocysteine and MMA, and a low vitamin B12. Management of this masked deficiency requires only vitamin B12 supplementation in contrast to initiation of plasmapheresis required for true TTP.
Related Knowledge Centers
- B Vitamins
- Cofactor
- DNA Synthesis
- Fatty Acid Metabolism
- Nervous System
- Protein Metabolism
- Metabolism
- Circulatory System
- Vitamin
- Myelinogenesis