Estimated AVERAGE requirement: calculated as the MEAN from a large # of experiments on ppl related to intake of specific nutrition to optimal FXN of MET processes and/or CELL fxns, depending on the nutrient
Recommended Dietary Allowance: 2 STDEVs ABOVE the MEAN (from EAR)
Should encompass 98% of population’s needs
Adequate Intake: Only when INSUFFICIENT DATA to do proper statistics based on intake studies of Apparently Healthy individuals.
This is used to ESTIMATE RDA only IF sufficient numbers of ppl have been tested
(Tolerable) Upper limit: HIGHEST intake of nutrient that poses minimal risk of toxic effects. Based on case by case and small studies of extreme intake
Diff b/w RDA and AI
Both Based on research on metabolic fxn of nutrient and optimal amts to MAXIMIZE that FXN.
RDA is calculated by statistics taking into account 98% of population: gives 2 stdev’s above the mean intake
AI is estimate of what the RDA MIGHT be: based on only a SMALL AMOUNT of research on a Few ppl
What were and why were Vitamin C RDA values change
Ascorbic acid RDAs increased 25%
This was due to new measurement techniques: Maximizing neutrophil uptake of ascorbic acid with minimal excretion via the urine.
Function of Vitamin C and its relation to RDA determination
Neutrophils rely on uptake Vitamin C in order for this nutrient to have an antioxidant role for neutrophils to fxn with their role of killing bacteria w/oxygen radicals and other oxidants
This biological fxn demands the HIGHEST dietary intake of Ascorbic acid compared to other fxns, so it is the RELEVANT MEASURE
Function of Vitamin E and its change in RDA
Vitamin E values increased 100%!
RDA based on measure of relating dietary intake of a-tocopherol (type of Vit E) to plasma levels of a-tocopherol and the fxn of preventing erythrocyte lysis.
This measure DIRECTLY determines the anti-oxidant fxn of a-tocopherol in a VALID biological role and that different forms of tocopherols are NOT metabolically interchangeable…ONLY alpha-tocopherol can be considered