Full form of RDA is Recommended Dietary Allowance.
What is RDA
It is the average daily dietary nutrient intake level sufficient to meet the nutrients requirements of nearly all (97 to 98%) healthy individuals in a particular life stage and gender groups.
Recommended dietary allowances are hence based on nutrient requirement.
Nutrient Requirements
What do we mean by the term “nutrient requirements”. It’s the requirement for a particular nutrient is the minimum amount that needs to be consumed to prevent symptoms of deficiency and to maintain satisfactory levels of the nutrient in the body.
How it varied
It depends upon the age, body, weight and physiological state of the individual.
Requirement+safety margin = Recommended dietary intake