Practitioners' guide to meeting the vitamin B-12 - Recommended Dietary Allowance for people aged 51 years and older

In response to research findings that 10% to 30% of people aged 51 years an d older may have protein-bound vitamin B-12 malabsorption, the National Aca demy of Sciences' Institute of Medicine recommends that these people consum e a majority of the new Recommended Dietary Allowance (RDA) of 2.4 mu g/day in its synthetic form rather than in its food form. Protein-bound vitamin B-12 malabsorption in older adults has been attributed to reduced pepsin ac tivity and gastric acid secretion, which interfere with cleavage of vitamin B-12 from dietary protein before absorption. Unlike patients with pernicio us anemia, most people with protein-bound vitamin B-12 malabsorption produc e intrinsic factor and have the ability to absorb synthetic vitamin B-12 no rmally. Early diagnosis is necessary to prevent the untoward effects of vit amin B-12 deficiency. A thorough assessment of vitamin B-12 status entails measurement of multiple biochemical assessment indexes, including serum vit amin B-12, methylmalonic acid, and homocysteine concentrations. Dietitians and other health care professionals should be aware of the prevalence of vi tamin B-12 deficiency in older adults and be familiar with sources of synth etic vitamin B-12 to facilitate implementation of the new RDA.