Define the Recommended Dietary Allowance for Vitamin B12 (RDA)?
Vitamin B12 deficiency is common in true vegans who can be treated with small doses since the daily requirement is only 1.0 mg/day, as you may have noticed in Table which presents the TCMR recommendations for vitamin B12 for all age groups. However, the requirements do increase in lactation by 0.5 mg/day.
The FAO/WHO 2004 recommendation also given in Table include both the estimated average requirement (EAR) and the recommended nutrient intake (RNI) calculated as the EAR plus 2 SD. FAO/WHO suggests a requirement of 0.7- 1.0 mg/day for those without pernicious anaemia. Since vitamin B12 is not completely absorbed from food, an adjustment of 50% has to be added, giving a range of 1.4-2.0 mg/day.