The primary function of vitamin B-12 is to aid in the formation of red blood cells. It is also vital in neurological function and in the synthesis of DNA. Individuals with pernicious anemia have inadequate levels of vitamin B-12, which leads to a reduced red blood cell and hemoglobin count, which in turn means your body may not be getting all the oxygen it needs.
Recommended Dietary Allowance for Adults
The recommended dietary allowance, or RDA, of vitamins and minerals is determined by the United States Department of Agriculture. The RDA of vitamin B-12 for healthy adults and adolescents over age 14 is 2.4 mcg per day. Women who are pregnant need 2.6 mcg of vitamin B-12, and breastfeeding mothers should consume 2.8 mcg of vitamin B-12 daily.
Seniors
According to the physicians at MayoClinic.com, as many as 30 percent of seniors over the age of 50 so not adequately absorb vitamin B-12 from foods in the diet. They recommend seniors eat foods fortified with additional vitamin B-12, like cereals and breads, and consult with a physician about supplementing with an additional 25 to 100 mcg per day.
Adequate Intake for Children
As with many other vitamins, no RDA of vitamin B-12 has been established for children under 14 years of age. Instead the USDA issues Adequate Intake levels. The AI of vitamin B-12 for infants up to six months is 0.4 mcg. Infants ages 7 to 12 months should consumer 0.5 mcg of vitamin B-12 daily. Toddlers ages one to three years should consume 0.9 mcg each day, and school-aged children ages four to eight years should consume 1.2 mcg daily. The AI for children ages nine to 13 is 1.8 mcg of vitamin B-12.
Dietary Sources of Vitamin B-12
The National Institutes of Health lists mead, fish and dairy products as the best natural sources of vitamin B-12. For example, a 3-oz. piece of rainbow trout contains 5.4 mcg of vitamin B-12, but a roasted chicken breast contains just 0.3 mcg. Yogurt contains 1.4 mcg per cup, while milk contains 0.9 mcg per cup. Fortified cereals and breads are both good sources of vitamin B-12 for vegetarians and populations at risk for vitamin B-12 deficiency, such as seniors, patients with pernicious anemia and those with gastrointestinal disorders or who have undergone gastrointestinal surgery.
Vitamin B-12 Supplementation
Vitamin B-12 supplements are available both over the counter and by prescription. According to the NIH, for every 500 mcg of supplement taken, approximately 10 mcg of vitamin B-12 are absorbed, which is adequate to recieve your total RDA. Physicians may prescribe vitamin B-12 injections or nasal gel to treat pernicious anemia and other B-12 deficiencies in at risk population.
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