Executive Summary Video
RDA or Recommended Dietary Allowance of a nutrient is the amount needed to take care of the daily needs of 97% of individuals in a group. In simpler terms, it is the amount that will keep most people from falling sick or at least, developing deficiency.
RDA was never designed for optimal nutrition. So why are we still using RDA for deciding our nutrient intake?
“The 1989 RDA consisted of a single reference point, with a focus on achieving sufficiency only, for individuals. However, the reference was often mistakenly applied as a standard for the evaluation of population nutrient intakes. In fact, the RDA is not appropriate for assessing the diets of individuals, or for assessing or planning the diets of groups.”
The Encyclopedia of Food Sciences and Nutrition
My Views
- RDAs are values that should be used to decide who is likely to face a problem due to deficiency of a nutrient. In that sense, they are like passing marks. People below those marks have obviously failed. But that should not be a benchmark for excellence.
- There is no sharp cutoff for our body’s needs. Why should 50 mg/day be sufficient and 49 mg/day be insufficient?
- A good analogy for RDA is money. If you get too little, you can’t even survive and feed yourself. So there is a cutoff like the poverty line, which is a subsistence level. But that is not the level that will give you lifelong safety. In case of medical emergency, you will not be able to survive on subsistence income, for example. Similarly, RDA levels are subsistence levels, not lifelong safe levels.
- There will be a day you will fall sick due to an infection, injury or some short-term event. On that day, you will be glad to have taken optimal levels of nutrients even when you did not need them.
- The reasons why RDAs are woefully short of optimal nutrition values are many.
- As per Dr Ames’ Triage theory, when faced with limited amount of a nutrient, our body adopts a hierarchy of needs. It apportions the nutrient to the most immediate need, shortchanging the long-term uses. So one does not notice any problem in the short term, while the effects become obvious years later, which RDA may not account for.
A good example is calcium. If you don’t take enough calcium, the body will make sure your muscles and heart will get it but not your bones. After all, your heart needs calcium for its electrical activity as well as pumping blood. You will die, otherwise. But you will not die if you have weaker bones, at least in the near future. So if you take sub-optimal levels of a nutrient, such as RDA, you will not face any problem in the short-term but in the long run, you will pay the price.
To Read More
- On this website: Recommended dietary intakes of various nutrients
- ScienceDirect: Various research publications on Recommended Dietary Intake
- National Academy of Sciences: What are dietary reference intakes
- Medical Research Education Associates: RDA’s vs Optimal Nutrition
- Nuskin (some more thoughts on this issue): Understanding the Nutritional Gap – RDA vs. Optimal Intake
First published on: 18th December 2021
Image credit: Andre Furtado on Pexels