Serum vitamin B12, serum folate and red blood cell folate levels were examined among 36 strict vegans of 5-35 years' duration.
Vitamin B12 levels among the vegans were generally lower than in a control population. Most of the vegans had vitamin B12 values less than 200 pg/ml.
None of the vegans had any hematologic evidence of vitamin B12 deficiency, however four of them had neurologic complaints. Long-standing vegans should be monitored for vitamin B12 levels.
Red blood cell folate levels were normal but serum folate levels among the vegans were higher than among the controls.
Recommended Dietary Allowance (RDA) - the average daily dietary nutrient intake level sufficient to meet the nutrient requirement of nearly all - ~97% - healthy individuals in a particular life stage and gender group.
The process for setting the RDA depends on being able to set an Estimated Average Requirement (EAR). If an EAR cannot be set, no RDA will be set. The EAR is the daily intake value of a nutrient that is estimated to meet the nutrient requirement of half the healthy individuals in a life stage and gender group.
The RDA is set at the EAR plus twice the standard deviation (SD) if known (RDA = EAR + 2 SD). If data about variability in requirements are insufficient to calculate a standard deviation, a coefficient of variation for the EAR of 10% is ordinarily assumed (RDA = 1.2 x EAR).
The RDA for a nutrient is a value to be used as a goal for dietary intake by healthy individuals. The RDA is not intended to be used to assess the diets of either individuals or groups or to plan diets for groups.