In 1941 the first Recommended Dietary Allowances (RDAs) were established by the Food and Nutrition Board of the National Academy of Sciences.   An RDA is the average daily dietary intake of a nutrient that is sufficient to meet the requirement of nearly all (97-98%) healthy persons.  These numerical values are also labeled as the RDI (Recommended Dietary Intake).   RDAs & RDIs are set as guidelines for different age groups; men and women and for pregnant and nursing mothers.   They provide nutrition guidance to health professionals and to the general public and are also used for many other purposes including development of new food products.  The Nutrition Board reviews these guidelines periodically and over time have both updated and expanded them.  Customers can find a reference to the RDAs and RDIs for vitamins on all product labels.