UK dietary reference values: EAR, RNI and LRNI
UK dietary reference values estimate how much energy or nutrient groups of healthy people need: lower reference nutrient intake (LRNI), estimated average requirement (EAR) and reference nutrient intake (RNI).
Remember
The EAR meets the needs of about half of a group, so it suits judging a group but is not a safe target for an individual. The RNI covers nearly all healthy people, while the LRNI covers only about 2.5%.
Mnemonic
Low, Average, Reference
- L Low
- A Average
- R Reference
Low, Average, Reference means the few, the half, and nearly all, running from the LRNI to the EAR to the RNI.
Dietary Reference Values are UK estimates of how much energy or how much of a nutrient groups of healthy people need. They assume a normal distribution, a bell-shaped spread of needs in which most people sit near the middle, while a few need far more or far less.
The three levels sit along that curve. The Lower Reference Nutrient Intake (LRNI) is at the low end, about two standard deviations (a standard measure of spread) below the average, and meets the needs of only about 2.5% of people. An intake below it is very likely to be inadequate for most people.
The Estimated Average Requirement (EAR) is the middle: the average need of a group, so about half of people need more than it and about half need less. That makes it the right benchmark for judging whether a group's usual intake is adequate. It is not a safe target for one person.
The Reference Nutrient Intake (RNI) is set high, about two standard deviations above the average, so it is enough for about 97% of people. It is the safe target when planning diets, because almost everyone will be covered, and it is the figure used for one healthy adult. For energy, the average is used instead of the RNI, because aiming that high would encourage weight gain.
A safe intake is different: it is a practical figure for a nutrient when there are not enough data to set the usual reference values. The Recommended Dietary Allowance (RDA) does not belong to the UK set of dietary reference values.
Key facts
- EAR
- the average requirement, so about half of people need more and about half need less.
- RNI
- set about two standard deviations above the average, so it is enough for about 97% of people.
- LRNI
- set about two standard deviations below the average, so an intake below it is very likely to be inadequate for most people.
- Group or individual
- the EAR suits judging whether a whole group is getting enough, while the RNI is the target used for one healthy adult.
- Safe intake
- a practical figure for a nutrient when there are not enough data to set the usual reference values.
- RDA
- the Recommended Dietary Allowance is not a UK dietary reference value.
Exam traps
- The RNI is not the benchmark for judging a community's usual intake of a nutrient, because it is set about two standard deviations above the mean as the target for one person.
- An intake below the EAR is not, by itself, the UK signal of a high risk of inadequacy, because the EAR is the central value of the requirement distribution; the signal is an intake below the LRNI, which is very likely to be inadequate for most people.
- The RNI is not a floor: it is set high enough for nearly all healthy people, so many people need less than it.
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