RDA's are updated to make sure dietary needs are met.
There were vitamins and minerals not even discovered when the United States Department of Agriculture (USDA) first published dietary guidelines in 1894. Research has since grown immensely, with the benefits of certain vitamins and minerals being touted frequently in the news. In 1941, the Food and Nutrition Board (FNB) of the National Academy of Sciences released the first set of Recommended Dietary Allowances (RDA's). The RDA is the daily dietary intake level of a nutrient that will meet the needs of 97 to 98 percent of healthy individuals. In 1993, the FNB began developing guidelines for revising the RDA's.
Experts Involved
The Standing Committee of the Scientific Evaluation of Dietary Reference Intakes (DRI Committee) was formed to oversee the updates. The DRI was developed in 1997 to broaden the RDA's existing guidelines (the DRI is not used on nutrition labels). The DRI Committee is divided into two subcommittees made up of experts in nutrition, dietetics, statistics, nutritional epidemiology, public health, economics and consumer perspectives. The experts must review scientific literature, provide guidance for use and identify inappropriate uses.
New Information
An accumulation of new information must be shown to support the reassessment of the RDA. There must be a reason to review and evaluate the current recommended levels. For example, studies have shown that there is a link between obesity and low vitamin D levels. Therefore, it has been suggested that the RDA for vitamin D be increased.The information should also include indicators of adequacy and indicators of possible adverse effects from excessive intake. There should be sufficient scientific literature available that has studied the use of the nutrient.
Reduction in Disease Risk
There should be data to support a reduction in chronic disease risk from taking a different amount of the nutrient. The studies should prove that the amount taken is safe as well as effective in reducing disease risk. The DRI Committee will review the evidence and provide guidelines to make sure the nutrient is used correctly.
Upper Levels of Intake
A safe maximum level of intake must also be established. Data must be available to explain the risk of adverse effects. Similar to not getting enough of certain nutrients, getting too much can also cause harm. Needs of different age groups and genders must also be addressed, since the RDA's are meant to meet the needs of the majority of the population.
Possible Health Benefits
Any other health benefits should also be examined. The DRI Committee will review the literature and provide guidance on use the nutrient at the proposed level for optimal benefit. There should be significance to public health demonstrated in the evidence, such as the reduced disease risks as mentioned above.
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