Vitamin B-12, a nutrient found in animal products such as organ meats, seafood, poultry, eggs and cheese, plays an important role in neurological function and the production of red blood cells. Prolonged vitamin B-12 deficiency can cause nerve damage and neurological disorders. Doctors typically use intramuscular B-12 injections or high oral doses to treat vitamin B-12 deficiency or malabsorption. Vitamin B12 deficiency and absorption problems can have many different causes, and treatments may vary in effectiveness, depending on the underlying cause. Appropriate treatment for vitamin B-12 deficiency depends on the patient's particular case and on her ability to absorb vitamin B-12.
Pernicious Anemia
Pernicious anemia, an autoimmune disease, causes significantly reduced levels of intrinsic factor, a glycoprotein necessary for vitamin B-12 absorption. Because individuals with pernicious anemia cannot absorb sufficient amounts of vitamin B-12 from food or supplements, doctors typically treat this condition with intramuscular injections of vitamin B-12. These injections bypass absorption problems associated with pernicious anemia. Without intrinsic factor, the body can only absorb 1 percent of oral vitamin B-12, meaning only high oral doses of B-12 could help treat pernicious anemia, notes the National Institutes of Health Office of Dietary Supplements.
Dietary Deficiencies
Vegetarians and vegans may not be able to get sufficient vitamin B-12 from food, because only animal products contain B-12 naturally. Oral B-12 supplements and foods fortified with B-12 can help prevent vitamin B-12 deficiency in vegetarians and vegans. Pregnant and lactating women who follow vegetarian or vegan diets should take B-12 supplements, notes the National Institutes of Health.
Other Absorption Problems
Insufficient levels of hydrochloric acid in the stomach can hinder the absorption of vitamin B-12 from food. Vitamin B-12 that occurs naturally in foods remains attached to protein until hydrochloric acid in the stomach separates the vitamin from the protein. Weight loss surgery, partial stomach removal surgery and atrophic gastritis can reduce the amount of hydrochloric acid secreted by stomach cells. Most individuals with atrophic gastritis can absorb synthetic vitamin B-12 from fortified foods and dietary supplements, because synthetic vitamin B-12 is already free and does not require hydrochloric acid for absorption. In these cases, B-12 injections may not be necessary.
Existing B-12 Deficiency
Doctors typically treat diagnosed vitamin B-12 deficiency with intramuscular injections, according to the National Institutes of Health. Injections bypass absorption problems and replenish B-12 levels efficiently. High oral doses of B-12 may provide an equally effective treatment for B-12 deficiency, however. In 2006, the journal "Family Practice" published a systematic review of randomized controlled trials dealing with oral and intramuscular B-12 treatments. Based on evidence from limited studies, the review concluded that oral doses of 2,000 mcg may be as effective as injections.
References
- "Family Practice"; Oral Vitamin B12 Versus Intramuscular Vitamin B-12 for Vitamin B-12 Deficiency: A Systematic Review of Randomized Controlled Trials; C.C. Butler, et al.; June 2006
- National Institutes of Health Office of Dietary Supplements: Vitamin B-12
- MedlinePlus Medical Encyclopedia: Vitamin B-12
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