All about fruitarianism with a long-term fruitarian, Lena

Those experiencing pernicious anemia (an auto-immune reaction to either the parietal cells or intrinsic factor) go on to develop vitamin B12 deficiency through malabsorption if untreated. Deficiency could develop within 1–3 years in those experiencing malabsorption. 

Patients having surgical alteration of the distal ileum, Crohn’s disease, and using metformin are also at an increased risk for malabsorption.

Herbert (1994) estimates that deficiency could take as long as 20–30 years to develop in persons having normal absorption/reabsorption and suddenly ceasing to include substantial amounts of vitamin B12 in their diet during adulthood. This is due to the large amount of vitamin B12 that can be stored in the body and recycled through enterohepatic reabsorption. 

The prevalence of vitamin B12 deficiency increases with age and is associated with a number of conditions and treatments.

The main causes of vitamin B12 deficiency are

  • poor dietary intake (as in vegetarianism),
  • poor absorption (occurring in achlorhydria, pernicious anemia, Helicobacter pylori (H. pylori) infection, Crohn’s disease, and metformin use),
  • poor distribution (genetic predisposition for aberrant proteins that are inefficient in transport or cellular uptake of vitamin B12).

George Berkeley

To be is to be perceived.

Recommended Dietary Allowance RDA

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. Apple