Vitamin B-12 is a water-soluble vitamin needed for red cell formation and nervous system function. Elderly people, those with altered gastrointestinal tracts, and certain people on long-term proton pump inhibitors have a decreased ability to absorb vitamin B-12 and may be at risk for deficiency.
Vitamin B12 Absorption
R-protein and intrinsic factor, or IF, are nonenzymatic proteins made in the stomach and play a role in vitamin B-12 absorption. Vitamin B-12 must be separated from food proteins before it can be absorbed. R-protein binds to vitamin B-12 before food proteins and is removed in the duodenum by pancreatic enzymes so it can be absorbed. IF is produced by parietal cells in the stomach, binds to vitamin B-12 and travels to the ileum where it is absorbed.
Age and B12 Absorption
Elderly people have the highest prevalence of B-12 deficiency of all age groups. Autoimmune atrophic gastritis, which causes B-12 malabsorption, is very prevalent in the elderly. This condition causes destruction of parietal cells; parietal cells produce intrinsic factor and are needed to absorb B-12.
Bowel Integrity
People with inflammatory diseases of the bowel, such as Crohn's disease, have a decreased ability to absorb vitamin B-12 when the ileum is affected. Gastric bypass surgery affects the amount of intrinsic factor available and, consequently, the amount of vitamin B-12 that can be absorbed. Both of these patient populations are at risk of developing deficiencies and often require intramuscular injections of vitamin B-12 to compensate for gastrointestinal inadequacies.
Long-term PPI Use in Elderly
Zollinger-Ellison syndrome is a genetic condition that requires long-term use of proton-pump inhibitors to decrease the overproduction of stomach acid that characterizes this condition. Proton-pump inhibitors decrease the amount of acid produced. In older patients with this disease, absorption of vitamin B-12 is markedly decreased and pharmacological doses are often required.
References
- "International Journal of Vitamin and Nutrition Research"; Bioavailability of Vitamin B12; L.H. Allen; October 2010
- "World Journal of Gastroenterology"; Safety of the Long-term Use of Proton Pump Inhibitors; A.B. Thomson, et al; May 2010
- "Diabetes and Metabolism"; Medical Follow Up After Bariatric Surgery: Nutritional and Drug Issues General Recommendations for the Prevention and Treatment of Nutritional Deficiencies; O. Ziegler, et al; December 2009
- "European Journal of International Medicine"; Serum Vitamin B12 and Folate Status in Patients with Inflammatory Bowel Diseases; M. Yakut, et al; August 2010
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