Unique among vitamins, cobalamin, or vitamin B12, is found almost exclusively in foods derived from animals. Persons who eat meat or meat products such as milk, cheese or eggs have no difficulty consuming enough vitamin B12, but persons who eat no animal-derived foods, or who have digestive problems may need an alternative source of vitamin B12.
Function
Vitamin B12 shots deliver this critical vitamin when a person’s body is not capable of absorbing the vitamin in the intestine.
Importance
A reliable source of vitamin B12 is essential to life. According to Eleanor Whitley and Sharon Rolfes in “Understanding Nutrition,” only a minute quantity, 2.4 micrograms per day, is required, but without it, the body cannot make new cells, maintain nerve cells, or break down some fatty acids and amino acids.
Why Needed
Vitamin B12 deficiencies generally result from inadequate absorption rather than inadequate intake. Poor absorption can result from lack of hydrochloric acid, or lack of intrinsic factor, a protein manufactured in the stomach to aid in the absorption of vitamin B12. Several conditions common among people over 60 years of age can damage stomach cells and prevent or reduce the production of hydrochloric acid.
These conditions include atrophic gastritis, iron deficiency and an infection caused by the Helicobacter pylori bacteria, which also can produce ulcers. Additionally, some people inherit a defective gene that prevents production of the intrinsic factor and, therefore, cannot absorb vitamin B12. With a shot or injection of vitamin B12, the body does not need to absorb this vitamin in the intestine.
Alternatives
Food sources of vitamin B12 include animal products such as meat, fish, poultry, shellfish, milk, cheese and eggs. Supplemental vitamin B12 sources include fortified soy milk and vitamin B12 supplements. Other forms of vitamin B12 include a nasal spray and sublingual, or under-the-tongue, products. The appropriate form depends on a person’s capability to absorb vitamin B12 in the intestine.
Considerations
Microwave cooking inactivates vitamin B12. To preserve the vitamin B12 in meats and milk products, cook with the oven or stove top rather than a microwave. According to Kathleen Mahan and Sylvia Escott-Stump, appreciable amounts of vitamin B12 can also be lost when milk is pasteurized or evaporated.
The body conserves vitamin B12 and stores it for years to use over and over. Even among vegetarians, a deficiency of vitamin B12 may take years to develop. According to the Centers for Disease Control and Prevention (CDC), 1 in 31 adults over age 51 years in the United States have low levels of vitamin B12. Because a deficiency of this vitamin develops slowly, symptoms may be overlooked but prevention and treatment are simple.
Vitamin B12 has no appreciable toxicity level and no reported toxicity symptoms.
References
- “Understanding Nutrition, Ninth Edition”; Eleanor Noss Whitney and Sharon Rady Rolfes; 2002
- “Krause’s Food, Nutrition, & Diet Therapy, 10th Edition”; Mahan and Escott-Stump; 2000
- CDC: Learn More About Vitamin B12 Deficiency
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