BOX 9-2Steps Used to Estimate the Vitamin B12 Requirement by Using Data Obtained from Subjects with Pernicious Anemia

Step 1Estimate the average intramuscular requirement for maintenance of person with pernicious anemia1.5 μg/day
Step 2Subtract estimate of extra losses due to lack of reabsorption of biliary B12− 0.5 μg/day
SubtotalEstimate average requirement of normal person for absorbed B121.0 μg/day
Step 3Correct for bioavailability (50 percent)÷ 0.5
ResultAverage requirement of normal person for B12 from food: Estimated Average Requirement (EAR)2.0 μg/day

From: 9, Vitamin B12

Cover of Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline
Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline.
Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline.
Washington (DC): National Academies Press (US); 1998.
Copyright © 1998, National Academy of Sciences.

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