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 and older may have protein-bound vitamin B-12 malabsorption, the National Academy of Sciences' Institute of Medicine recommends that these people consume a majority of the new Recommended Dietary Allowance (RDA) of 2.4 micrograms/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 activity and gastric acid secretion, which interfere with cleavage of vitamin B-12 from dietary protein before absorption. Unlike patients with pernicious anemia, most people with protein-bound vitamin B-12 malabsorption produce intrinsic factor and have the ability to absorb synthetic vitamin B-12 normally. Early diagnosis is necessary to prevent the untoward effects of vitamin B-12 deficiency. A thorough assessment of vitamin B-12 status entails measurement of multiple biochemical assessment indexes, including serum vitamin B-12, methylmalonic acid, and homocysteine concentrations. Dietitians and other health care professionals should be aware of the prevalence of vitamin B-12 deficiency in older adults and be familiar with sources of synthetic vitamin B-12 to facilitate implementation of the new RDA.
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Department of Food Science and Human Nutrition, University of Florida, Gainesville 32611, USA.
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Bailey
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D000042:Absorption; D000367:Age Factors; D000368:Aged; D004044:Dietary Proteins / Q000378:metabolism; D006402:Hematologic Diseases / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D008286:Malabsorption Syndromes / Q000517:prevention & control*; D008875:Middle Aged; D009422:Nervous System Diseases / Q000209:etiology / Q000517:prevention & control; D018673:Nutrition Policy; D011485:Protein Binding; D014805:Vitamin B 12 / Q000008:administration & dosage* / Q000493:pharmacokinetics; D014806:Vitamin B 12 Deficiency / Q000150:complications / Q000517:prevention & control*
D004044:Dietary Proteins; D014805:Vitamin B 12