Recommended Dietary Allowances

The Recommended Dietary Allowances (RDAs) were created in 1941 by the Food and Nutrition Board, a subsidiary of the National Research Council which is part of the National Academy of Sciences in Washington, DC.

The first RDA committee surveyed the research literature and formulated a tentative set of values for various nutrients known at that time for persons of different age group, for both sexes and during pregnancy and lactation.

RDAs are intended to reflect the best scientific judgment on nutrient allowances for the maintenance of good health and to serve as the basis for evaluating the adequacy of diets of groups of people.

RDAs originally were designed to make planning several day’s meals in advance easy for people. The D in RDA stands for dietary, not daily, because the RDAs are an average. You may get more of a nutrient one day and less the next, but the idea is to hit an average over several days.

For example, the current RDA for vitamin C is 75 mg for a woman and 90 mg for a man (age 18 and older). One 8 ounce glass of fresh juice has 120 mg vitamin C, so a woman can have an 8 ounce glass of orange juice on Monday and Tuesday, skip Wednesday and still meet the RDA for the three days.

The amount recommended by RDAs provide a margin of safety for healthy people, but they’re not therapeutic. In other words, RDA servings won’t cure a nutrient deficiency, but they can prevent one from occurring.

The National Academy of Sciences has established three new categories of dietary guidelines to work alongside the RDAs and it has place all three categories, as well as the RDAs themselves, under a new umbrella heading called dietary reference intakes (DRIs).

In other words, as of 1997, the RDAs are now a subdivision of the DRIs.

The three additional categories of recommendations are as follows: adequate intakes, estimated average requirements, and tolerable supper intake levels.
Recommended Dietary Allowances