Evaluation of a new Recommended Dietary Allowance for folate

This article analyzes the 1989 Recommended Dietary Allowance (RDAs) for folate, which are approximately 50% less than the amounts recommended previously. The RDA committee used the following types of data to estimate allowances: (a) the quantity of folate required to elicit established physiologic responses or replace daily losses corrected for bioavailability and individual variability and (b) dietary folate intake data related to prevalence of deficiency in population groups. Some studies cited by the committee evaluated the response to synthetic folate, whereas other studies used dietary folate to estimate folate requirements. Responses to these two forms of folate may differ and depend on the individual's state of folate depletion. The correction for bioavailability is an estimate based on limited data determined by various experimental approaches. Estimates of the folate content of food vary as a function of a number of factors in the method of analysis and the specific type of food consumed. Additional variables include food preparation, food losses, and nutrient interactions. For these reasons, estimates of folate intake based on computer databases may not accurately reflect folate consumed or physiologically/metabolically available folate. Assumptions that current dietary intakes of folate are sufficient to maintain status in the US population were based, in some cases, on data from population surveys not designed to assess folate status. The new RDAs for folate may not provide an adequate safety allowance for specific population groups at risk and should be reevaluated as new information evolves.