Chapter 2


Figure 2.2 Relationship between various reference values


Nutrient Requirements


Lower Reference
Nutrient Intake
(LRNI)


Estimated Average
Requirement
(EAR)


Reference
Nutrilent Intake
(RNI)


Source: Dietary Reference Values: A Guide, Department of Health, London 1991

The diagram shows the estimated average requirement, which is the mean of the range of
individual requirements. It is assumed that individual requirements are normally distributed
around that mean. The RNI is set at the mean plus two standard deviations, which means that
that amount of the nutrient is enough for almost every individual, even those with high needs.
Thus this minimises the chances of assessing an individual as having an adequate intake of
the nutrient when in fact they are, deficient. It also shows the lower reference nutrient
intake at the mean minus two standard deviations. This is a yardstick which is increasingly
being used as indicating an amount of the nutrient which would be enough only for a very
small amount of the population. Thus if people are normally eating less than the LNRI, they
will almost certainly be deficient in that nutrient. Because it is impossible to tell what an
individual's requirements are, with out undertaking expensive laboratory work, it is difficult
to say with any accuracy whether an individual has adequate intake of any specific nutrient if
their intake lies between the LRNI and the RNI. However, if we are looking at group data,
then the larger the group, the more likely that their intake should be at or above the EAR if
they are, in fact, adequately nourished.


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