Vitamin B12, also known as cobalamin, is a large, complex molecule primarily associated with higher brain functions, red blood cell production and cellular metabolism. Those with dementia symptoms or blood anemia sometimes supplement with B12, although deficiency can be masked by high levels of folic acid and become difficult to determine. B12 is found with other B vitamins in foods such meat, fish, dairy products, green leafy vegetables and legumes.
B12 Types
Within food, B12 exists as cobalamin, whereas cyanocobalamin is the most common synthetic supplement. A less common and more expensive synthetic form is hydroxocobalamin, which is better absorbed in the large intestine. All forms of B12 require a compound called intrinsic factor to be present in the intestines to be properly absorbed, which can be in short-supply within the elderly, notes Advanced Nutrition: Macronutrients, Micronutrients and Metabolism. The elderly may benefit the most from taking hydroxocobalamin.
B12 Daily Requirements
Adults require between 2 mcg and 3 mcg of vitamin B12 per day to avoid deficiency symptoms, says Vitamins: Fundamental Aspects in Nutrition and Health. However, because of the poor absorbability of B12, some people may have to supplement with at least 500 mcg to absorb the required amounts. To enhance absorption, it is recommended that B12 be taken without food or under the tongue. Those diagnosed as deficient sometimes get B12 injections instead, usually one per month until blood levels normalize.
B12 Deficiency
"Human Biochemistry and Disease" states that normal blood levels of B12 should range from 200 to 600 picograms per milliliter within adults. Symptoms of deficiency can take five years or more to develop because B12 is the only water-soluble vitamin to be stored in the body long-term. B12 deficiency symptoms include pernicious anemia, characterized by immature red blood cells, and neurological complications that are very similar to those of Alzheimer's disease, such as impaired cognitive functions, reduced short-term memory recall and depression. B12 should not be taken with high levels of folic acid because it can mask a deficiency issue. In fact, up to 20 percent of Alzheimer's cases in the United States may be B12 deficient and greatly benefit from supplementation, notes Nutrition in Public Health.
B12 Recommendations
According to "Nutritional Sciences," supplementing with B12, even in megadoses, is safe because it has such low toxicity, despite being stored in the body. As such, typical recommendations for those with pernicious anemia or symptoms of senile dementia are to take between 1,000 mcg and 2,000 mcg of B12 daily. Taking it early in the day may be more beneficial as it takes time to absorb and be utilized. Additionally, because B12 is involved in cellular metabolism and energy production, supplementing at night may disrupt the sleep of some users. Vegetarians who avoid beef, poultry, fish and dairy products are at higher risks of B12 deficiency, which is why some supplement with B vitamins. However, Nutrition and Diagnosis-Related Care states that diets rich in green leafy vegetables, legumes, nuts and vegetable oils seldom lead to B12 deficiency issues, unless you have a malabsorption condition.
References
- Advanced Nutrition: Macronutrients, Micronutrients, and Metabolism; Carolyn D. Berdanier; 2009
- The Vitamins: Fundamental Aspects in Nutrition and Health; Gerald Combs; 2008
- Human Biochemistry and Disease; Gerald Litwack; 2008
- "Nutrition in Public Health; Sari Edelstein; 2006
- "Nutritional Sciences"; Michelle McGuire; 2007
- Nutrition and Diagnosis-Related Care; Sylvia Escott-Stump; 2008
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