Prevention of Vitamin B12 Deficiencies
“The . . . Recommended Dietary Allowance (RDA) (2.4 mcg/day) for B12 for adults ages 51 and older are the same as for younger adults but with the recommendation that B12–fortified foods (such as fortified ready-to-eat cereals) or B12–containing supplements be used to meet much of the requirements.” Institute of Medicine, 1999
The irreversible nature of late stage neurologic effects of a vitamin B12 deficiency provides strong support for the value of prevention.
The irreversible nature of late-stage neurologic effects of a vitamin B12 deficiency provides strong support for the value of prevention.44,50,83 Fortunately, vitamin B12 deficiency is easily treated and prevented. Because of the high prevalence of mild, subclinical cobalamin deficiency in asymptomatic individuals, it is important to remain vigilant, especially with individuals at high risk for vitamin B12 deficiency. If “watch and wait” is the selected plan of care, periodic reassessment of untreated asymptomatic patients is important to identify progressive depletion of vitamin B12.
The Institute of Medicine (IOM) recommends that all adults 18 years of age or older consume 2.4 micrograms (µg) per day of vitamin B12.10 Subclinical vitamin B12 deficiency, often undiagnosed and untreated, has been estimated to occur in 5% to 15% of the elderly population.4,6,16,19,65 A recent clinical study demonstrates that it takes 650 µg to 1,000 µg of cyanocobalamin daily to provide 80% - 90% of the estimated maximum reduction in methylmalonic acid.80
Given the high prevalence of atrophic gastritis (loss of acid secretion) in older adults, the IOM suggests that adults older than 50 years of age use vitamin B12–fortified foods and supplements (e.g., multivitamins or single supplements) as the primary means to meet this requirement because crystalline formulations are much more readily absorbed and used than naturally occurring vitamin B12. Most multivitamins contain 6-25 µg cyanocobalamin; some contain more. Single supplements typically come in doses of 100 µg, 250 µg, 500 µg, 1,000 µg, and 2,000 µg. For more information on vitamin supplements for adults, see the National Institutes of Health Office of Dietary Supplements website at http://ods.od.nih.gov/factsheets/cc/vitB12.html
Vegans, or strict vegetarians, must obtain their per day dose of vitamin B12 by consuming a vitamin supplement or eating a fortified cereal product. Currently available data do not support the suggestion that vegans can meet their minimum daily requirements for vitamin B12 by consuming unfortified plant-based foods, nutritional yeast, algae, or seaweed products.
For more information on the vitamin B12 levels of over 1,100 common food items, visit the U.S. Department of Agriculture and Agricultural Research website at http://www.ars.usda.gov/ba/bhnrc/ndl.
Several experts in the field find that even higher doses of oral cobalamin are necessary for the prevention of vitamin deficiency among the elderly and have stated that the amount in the IOM recommendation is insufficient80 (Carmel RA. New York Methodist Hospital [personal communication] 2006-2007; Allen RH. University of Colorado [personal communication] 2006-2007). Lindenbaum’s findings of the prevalence of cobalamin deficiency in the elderly survivors from the Framingham study suggests “deficiencies can, at least in part, be prevented by oral supplementation, although . . . the dose of cobalamin administered may have to be much larger than that usually given in routine multivitamin preparations.”4
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