RECOMMENDED DIETARY ALLOWANCE (RDA)
“RDA is the minimum amount of that particular nutrient in diet which prevents deficiency in 97.5% persons in a group. Even after meeting the RDA requirement, there may be deficiency symptoms in 2.5% persons. These RDA levels don’t fit in accordance with health. These nutrients are having an upper level also and they are safe, even if we consume at this level for a long period. This level is called upper Intake and it is usually several times higher than RDA. RDA don’t meet the criteria of optimum health defined by W.H.O. At this level our all bodily functions don’t work properly (Optimally). This level don’t cause deficiency symptoms, but if we take this amount for prolonged period, then our other metabolic functions don’t work efficiently.
Homeostatic mechanism comes into play. After a prolonged period we get metabolic diseases.
Example :We can understand it very well with an example of Vitamin A. RDA of Vit.A is 600-900 mg/day and upper Intake level is about 3000 mg/day. Optimum amout of this vitamin should be in between these two levels i.e. 2000 mg/day. At this level our all metabolic function will work efficiently and we will also not be getting toxicity. Take another example of Vitamin D. It’s RDA is 400-800 i.u. while upper safe level is 8000 i.u. Optimum requirement of vitaminD is 5000 i.u.
These RDA levels should be changed for optimum requirement to prevent & cure of chronic lifestyle diseases & for optimum health as directed by W.H.O.