Vitamin B-12 aids folic acid in the formation of red blood cells and helps in the utilization of iron. A B-12 deficiency may result in anemia, poor digestion, impaired growth and development, infertility and nerve damage. Vitamin B-12 aids memory, learning, mood and sleep. Injections are commonly prescribed to treat B-12 deficiency, which may occur for several reasons.
Dietary Deficiency
Vitamin B-12 is found in meat, milk, eggs, fish, brewer's yeast, blue-green algae and seaweeds. It may be added to nutritional yeast and cereals. Deficiency may be associated with economic hardship, poor diet and chronic alcohol abuse. Vegans and vegetarians, who avoid foods from animal sources, may be at high risk for vitamin B-12 deficiency. A study, published in 2000 in the "Annals of Nutrition and Metabolism," in which 49 subjects consumed a mostly raw vegan diet of fruits, vegetables, nuts and seeds for at least two years revealed low B-12 levels in the total study population, with six individuals showing severe deficiency.
Loss of Intrinsic Factor
Gastric parietal cells in the digestive tract produce intrinsic factor, which is necessary for the absorption of dietary B-12. Naturally occurring intrinsic factor can absorb approximately 56 percent of a 1 mcg vitamin B12 dose, according to The Office of Dietary Supplements. A lack of intrinsic factor may be genetic. The loss of gastric parietal cells in the digestive tract may occur due to bariatric surgery for weight loss, short bowel syndrome that may result from surgery for Crohn's disease, the side effects of untreated celiac disease and atrophic gastritis, a condition associated with aging. The Office of Dietary Supplements reports that atrophic gastritis affects approximately 10 to 30 percent of older adults.
Medications
Medications for the treatment of gout, blood thinning drugs and potassium supplements may block the absorption of vitamin B-12 in the digestive tract. Because B-12 must be released from protein in food by hydrochloric acid and enzymes, medications that reduce stomach acid, known as proton pump inhibitors, may interfere with this process. Proton pump inhibitors are found in over-the-counter remedies for heartburn and are prescribed for the treatment of gastroesophageal reflux disease and peptic ulcers. Medication for type 2 diabetes may also contribute to vitamin B-12 deficiency. Metformin was associated with B-12 deficiency in a Hong Kong study. The research was case-controlled with 155 subjects who were B-12 deficient secondary to metformin use and 310 controls on metformin without deficiency. Adjusting for other factors, scientists found clinically significant links to dose and duration of metformin use. A 1 gm higher increment nearly tripled the odds of acquiring B-12 deficiency as did taking the medication for three or more years. After exclusion of 113 subjects with borderline B-12 levels, dose remained the strongest independent predictor of deficiency. The findings were published in the October 2006 "Archives of Internal Medicine."
References
- "Annals of Nutrition and Metabolism," Metabolic Vitamin B12 Status On a Mostly Raw Vegan Diet With Follow-up Using Tablets, Nutritional Yeast, or Probiotic Supplements, Donaldson M.S.; 2000
- Office of Dietary Supplements: Vitamin B12
- "Archives of Internal Medicine," Risk Factors of Vitamin B(12) Deficiency in Patients Receiving Metformin, Ting R.Z., et al., Oct. 9, 2006
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