Recommended Daily Intakes (RDI) also known as (also Recommended Daily Allowances)
are not the best guidelines.
1) The RDI's were not originally intended to be a guideline for optimum health, but rather the guide to a bare minimum intake to fend off disease
2) They are usually several years behind current research, as shown by the fact that the intakes are mostly increasing with every revision
3) The UK and US populations, which are regarded as the “healthy” baseline, are not healthy at all. This is a poor reference point and not a good guideline.
However, to understand why these are no longer an appropriate guide, you need to first understand how they came about.
Let’s take a little trip back in time, to 1941.
The original Recommended Daily Allowances
As the United States was about to enter World War II the government needed an accurate measure of nutrients a person would need to survive, without contracting diet-related diseases.
Lydia J. Roberts, Hazel K. Stiebeling and Helen S. Mitchell were to create a guide for the military to estimate food supplies of soldiers overseas and relief efforts to war-torn areas.
**Note: the objective was to determine what the minimum level of nutrients a person could survive on, not to sustain optimal health.
In 1941, the final recommendations were accepted by the National Academy of Sciences and the first RDA’s were published.
As nutrition researchers learned more, they discovered (belatedly) that the common sense rule of “horses for courses” applied to human nutrition as well.
It turned out that humans, because of genetic or lifestyle factors, require different levels of nutrition, since all of us are different.
A major overhaul of the RDA’s was completed in 1989 to reflect this fact.
The new RDI
In 1993, the old Recommended Daily Allowances were replaced, as they were considered far behind the current medical research.
In the European Union, new RDA’s were issued by the UK government, to be called Dietary Reference Values (DRV’s).
The DRV’s consisted of not one value per mineral, but several different values for each nutrient, listed below.
Estimated Average Requirement (EAR) – This should meet the minimum requirements of half of the population, bearing in mind individual differences in nutrient needs.
Reference Nutrient Intake (RNI) - This should represent the requirements of 97 percent of the population. (We still think this is too low – please read on to find out why)
Lower Reference Nutrient Intake (LRNI) – This is the intake for people who’s needs are very low. Anyone below this is running a serious risk of a deficiency like scurvy or pellagra.
The United States came up with a similar system called the Dietary Reference Intake in 1997. They also added a tolerable upper limit (TUL) category to warn against synthetic supplement toxicity.
What they are used for
Today, they are used for planning emergency relief supplies, a baseline measurement on food containers and in food and nutrition education programmes.
Changes over time
One other reason that the RDA’s may not be your best guide, is that they have been continually increasing the intakes for the vitamins and minerals, several years behind current research.
For example, the RDA for Vitamin C went from 30mg to 45mg to 60mg in the UK.
In the US, it’s currently 85mg.
These values are far behind the times.
How they are calculated
One of the key tools the researchers use to set RDA’s, DRV’s and other acronyms is population-based studies. That is, they study an apparently healthy population and break down what they eat to use as a guide for others.
This is an over-simplification, but please bear with me.
The easiest, cheapest, most available population data on nutrition is derived from the United States and United Kingdom.
These are not healthy societies.
Let’s take a look at some stats for the UK, courtesy of the National Diet and Nutrition Survey of the UK Office of National Statistics.
Some fast facts about our health in the UK
q The UK has the highest rates of Cardio-Vascular Disease (CVD) in Europe
q 44% of men and 46% of women have one or more chronic longstanding illnesses
q 65.4% of men and 55.5% of women are overweight or to obese
In the US, over 65% of the adult population is overweight or obese.
Some researchers even claim that 75% of us die from lifestyle-related diseases that could have been prevented or slowed with a reasonably healthy lifestyle.
So, is this is the best population to use as a “healthy” example to base national guidelines on?
Of course not, but it’s done because the data is cheap and easy to obtain.
A better solution
There are a variety of other doctors that have suggested optimal amounts of nutrients, based on years of research.
Our favourite is Dr. Paul Clayton’s Suggested Optimal Daily Amounts (SODA) as outlined in his book Health Defence. It’s packed with interesting research and statistics and well worth a read.
His website is
What should you do now?
Our suggestion is to evaluate the facts for themselves.
Is a good set of guidelines for health based on:
1) Data that wasn’t originally intended to gain optimum health?
2) Data that was continually revised, behind current research?
3) Data based on the “healthy” UK and US populations?
If you don’t think so either, then it’s time to find some supplements and throw out any idea of “getting your nutritional needs from food alone”.
Please see our favourites suggestions here.
Back to Home Page from RDI