What is United States Recommended Daily Allowances- USRDA

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Misty L. Trepke

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What Is United States Recommended Daily Allowances (USRDA)

 

USRDAs were devised by the Food and Drug Administration for

nutritional labeling. These are the lists on processed foods and

vitamin products that tell what percentage of each of 19 essential

nutrients you get per serving or dose. It is a rough guide because

it doesn't differentiate among people of different ages and sex who

have different nutrient requirements.

 

The USRDAs, in turn, are based on the RDAs- Recommended Dietary

Allowances derived by a prestigious group of nutritional scientists

who advise the Food and Nutrition Board, a committee of the National

Academy of Sciences-National Research Council. Every five years or

so, the board reviews and revises its recommendations. As the board

defines them, the RDAs are " the levels of intake of essential

nutrients considered, in the judgment of the Food and Nutrition

Board on the basis of available scientific knowledge, to be adequate

to meet the known nutritional needs of practically all healthy

persons. "

 

Except for vitamins A and D, it's not harmful to consume two to

three times the recommended levels of vitamins. Many people

regularly do through the foods they eat and especially if they take

a multivitamin supplement.

 

Shortcomings of the Recommended Daily Allowances

 

There are some caveats regarding the RDAs. The board that

established them admits that scientific knowledge of nutritional

requirements is far from complete: that the requirements for many

nutrients have not been established; that several essential

nutrients have only recently been discovered; and that in

all likelihood other nutrients will be found to be essential in

years to come. Therefore, to be sure that as yet undefined

nutritional needs are met, it's important to eat a varied diet and

not depend on pills or processed foods artificially stoked with

known micronutrients.

 

The RDAs should not be confused with nutritional requirements.

Requirements differ from individual to individual because of

inherent genetic differences, among other factors. Therefore, the

RDAs represent estimates that exceed the requirements of most people.

 

The RDAs were developed for healthy people under normal

circumstances (i.e., no illness, no genetic weaknesses, no

environmental toxin exposure) to prevent the development of overt

deficiency diseases. They were not developed to serve as a

guide to determining optimal nutritional needs.

 

In addition, the studies that were used to determine the level of a

nutrient sufficient to prevent a nutritional deficiency were

typically conducted for six to nine months, only about 1% of the

average human life span. Nutritional studies with animals have shown

that the amounts of some nutrients sufficient to provide health and

the prevention of a deficiency disease for short periods of

time may be totally inadequate to maintain the health of the animal

over its entire lifespan.