Lesson 9: Vitamins
9.1 Introduction
Vitamins are essential nutrients that are required in small amounts for normal metabolism. Four fat-soluble vitamins (A, D, E and K) and 9 water-soluble vitamins (C and 8 vitamins from the "B” group) have been described. Preterm infants are born with low levels and limited stores of fat soluble vitamins. On the other hand, plasma concentrations of water-soluble vitamins are high at birth, due to active placental transfer. However, as storage is not possible, their concentrations fall very rapidly.
A term healthy infant will get enough nutrition being breastfed. However, preterm infants will require vitamin supplementation soon after birth. Most VLBW and ELBW at birth are either too unstable or too sick for full enteral feeding. Moreover the vitamin content in human milk at this stage might be insufficient for the preterm infant. Hence, parenteral vitamin supplementation may be the initial form of delivery for many preterm infants (Leaf & Lansdowne 2014).
Calculating the specific vitamin requirements for supplementation is challenging. The value depends on vitamin levels at birth and stores. The stores are closely related to maternal status, gestation, and individual metabolic capacity.
An overview of vitamin action, sources and effects, in addition to vitamin placental transfer and status at the preterm birth will be discussed in this lesson. Specific requirements are given in lesson 9.5, table 7.