Defining the nutritional needs of preterm infants.

Nutritional needs are defined as the amount and chemical form of a nutrient needed to support normal health, growth and development without disturbing the metabolism of other nutrients. Nutrient intake recommendations are based on the estimated average requirement (EAR) of a population group. Enteral and parenteral needs differ for many nutrients because of differences in bioavailability and utilization. Assuming a near-normal distribution of nutrient needs, the reference nutrient intake (RNI--also called population reference intake or recommended dietary allowance) is equal to the EAR plus two standard deviations of the distribution, with the exception of energy intake where the reference intake is equal to the EAR. The upper level (UL) is the highest level of intake where no untoward effects can be detected in virtually all individuals in a specific population group. The acceptable range of intakes (AR) is the range from the EAR to the UL that is considered safe, however preterm infants are not a homogeneous population thus intake often needs to be individualized based on clinical condition and developmental stage.