Term infants and children appear to adapt to large variations in vitamin intakes. This is supported by the finding of similar blood levels of vitamins despite several-fold differences in intake on a body weight basis. By contrast, the finding of marked elevation of some vitamins and low levels of others seen in very-low-birth-weight (VLBW) infants (< 1500 g) suggest that this group has less adaptive capacity to high- or low-dose intakes. This indicates that their vitamin intakes need to be more closely aligned with actual needs. This paper reviews previously published data on vitamins A, E, B2, and B6 from VLBW infants receiving total parenteral nutrition (TPN). Vitamin A. VLBW infants are relatively deficient in retinol (R) at birth. During TPN large losses of R onto the delivery sets result in a further decline in stores of R as reflected in a progressive decline in plasma in R during TPN. Because of the reported lower incidence of bronchopulmonary dysplasia associated with intramuscular vitamin A treatment, alternative methods of vitamin A delivery during TPN have been suggested. First, the vitamins were mixed with Intralipid (IL) and, second, retinyl palmitate (RP) rather than R was used. There was little in vitro loss of R when mixed with IL, and in vivo treatment resulted in higher blood levels after 1 month of retinol administration in IL than seen previously (21 +/- 4.2 vs 14.1 +/- 3.7-mu-g/dl). Use of RP in VLBW infants resulted in high RP levels (40 +/- 6-mu-g/dl), although R levels were similar to that seen with R added to IL (21.1 +/- 4-mu-g/dl). Using these data and those from other publications, currently suggested intravenous intake of vitamin A as R is 500-mu-g/kg/day. Vitamin E. The TPN solution for pediatric patients contains alpha-tocopherol acetate. Little of the vitamin is lost to the plastic infusion sets. Infusion of four different dosage levels suggests that doses of 2.8-3.5 mg/kg/day will maintain most infant blood levels between 1 and 2 mg/dl. Vitamin B2. Vitamin B2 is activated to its active cofactor forms flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Three doses of riboflavin (0.68. 0.56. and 0.34 mg/kg/day) resulted in elevated blood levels. Using these blood response doses, a projected intake of 0.15 mg/kg/day) appears more appropriate to maintain blood levels in the range of those seen in formula-fed term infants. Vitamin B6. Vitamin Be is converted in vivo to pyridoxal and activated to its cofactor form, pyridoxal phosphate (PLP). Three doses of pyridoxine (from 0.2 to 0.5 mg/kg/day) resulted in elevated blood levels. Using the blood response to these doses. an intake of 0.18 mg/kg/day is projected to maintain PLP levels within the range of that seen in plasma samples from formula-fed term infants.
