Vitamin E requirements of preterm infants

Dosage and formulation issues: oral vitamin E therapy in children

PURPOSE

Oral vitamin E is used in several childhood diseases, but dosage recommendations differ. Few oral products have a marketing authorization for therapeutic use in children. Preliminary data indicate differences in bioavailability among the various vitamin E compounds. Our objective was to review published data on oral vitamin E therapy in neonates and children in order to establish dosage recommendations at a local level.

METHODS

A literature search was conducted, including Medline Ovid, EMBASE (1980-Feb 2008), Cochrane databases, product monographs, handbooks, and textbooks.

RESULTS

The main vitamin E compounds being used in children are alpha-tocopherol, alpha-tocopheryl acetate, and tocofersolan. The most data are available on tocopheryl acetate, both in neonates and older children. In children with malabsorption disorders, tocofersolan appears to have an increased bioavailability compared to tocopherol or tocopheryl acetate. Published data on pharmacokinetics and dosages for clinical use are few and heterogeneous. No pharmacokinetic studies were found for tocofersolan in neonates and infants. There are few comparative studies on pharmacokinetics, therapeutic use, and adverse drug reactions (ADRs) in children. Dosages used in clinical studies and dosage recommendations in handbooks differ considerably.

CONCLUSIONS

The differences in dosing recommendations in children may be due to lack of systematic studies. Existing published data on oral vitamin E do not provide a basis for evaluation of dosage recommendations in children. Comparative clinical studies are required for scientific evaluation of pharmacokinetics, dosage regimens, and efficacy/ADR assessments in children.

Effects of vitamin E supplementation during erythropoietin treatment of the anaemia of prematurity

AIMS

To evaluate the effects of vitamin E supplementation on haemoglobin concentration and the requirement for transfusion in premature infants treated with erythropoietin and iron.

METHODS

Randomised, double blind, placebo controlled trial. Thirty infants </=32 weeks gestation and </=1250 g birth weight, who were defined as stable based on minimal requirements for respiratory support and phlebotomy, and absence of major congenital anomalies were enrolled. All were treated with erythropoietin and iron, and were randomised to receive, in addition, either vitamin E 50 IU/day or placebo for eight weeks or until discharge, whichever came first.

RESULTS

Despite higher vitamin E (alpha-tocopherol) levels in the experimental group in weeks 3 (49.0 v 28.1 micro mol/l) and 8 (66.2 v 38.5 micro mol/l), there were no differences in haemoglobin, reticulocyte count, iron concentration, or transfusion requirement.

CONCLUSIONS

Oral vitamin E supplementation at 50 IU/day does not increase the response of preterm infants to erythropoietin and iron. Vitamin E obtained through standard nutrition may have been sufficient or higher doses may be required.

Vitamin E supplementation for prevention of morbidity and mortality in preterm infants

BACKGROUND

Treating very low birth weight (VLBW) infants with pharmacologic doses of vitamin E as an antioxidant agent has been proposed for preventing or limiting retinopathy of prematurity, intracranial hemorrhage, hemolytic anemia, and chronic lung disease. However, excessive doses of vitamin E may result in side effects.

OBJECTIVES

The aim of this systematic review was to assess the effects of vitamin E supplementation on morbidity and mortality in preterm infants.

SEARCH STRATEGY

We searched MEDLINE (October 2002), EMBASE (March 2002), the Cochrane Controlled Trials Register (CCTR) from the Cochrane Library, 2003, Issue 1, and personal files for clinical trials assessing vitamin E in preterm infants.

SELECTION CRITERIA

We selected trials analyzing primary outcomes (mortality or combined long-term morbidity) or secondary outcomes (other morbidity) in infants with gestational age less than 37 weeks or birth weight less than 2500 grams. The intervention was allocation to routine supplementation with vitamin E in the treatment group versus placebo, no treatment or another type, dose or route of administration of vitamin E.

DATA COLLECTION AND ANALYSIS

We used standard methods of the Cochrane Collaboration and of the Cochrane Neonatal Review Group.

MAIN RESULTS

Twenty-six randomized clinical trials fulfilled entry criteria. No study assessed combined long-term morbidity. Routine vitamin E supplementation significantly reduced the risk of germinal/intraventricular hemorrhage (typical relative risk [RR] 0.85, 95% confidence interval [CI] 0.73, 0.99), increased the risk of sepsis (typical RR 1.52, CI 1.13, 2.04) and increased hemoglobin concentration by a small amount, but did not significantly affect mortality and other morbidity. In VLBW infants, vitamin E supplementation increased the risk of sepsis, and reduced the risk of severe retinopathy and blindness among those examined. Subgroup analyses in VLBW infants showed (1) an association between serum tocopherol levels greater than 3.5 mg/dl and increased risk of sepsis and reduced risk for severe retinopathy among those examined; and (2) an association between intravenous, high-dose administration of vitamin E and increased risk of sepsis.

REVIEWER'S CONCLUSIONS

Vitamin E supplementation in preterm infants reduced the risk of intracranial hemorrhage but increased the risk of sepsis. In very low birth weight infants it increased the risk of sepsis, and reduced the risk of severe retinopathy and blindness among those examined. Evidence does not support the routine use of vitamin E supplementation by intravenous route at high doses, or aiming at serum tocopherol levels greater than 3.5 mg/dl.

Studies on the tocopherol status in blood serum of premature babies and infants

The level of naturally occurring tocopherols in blood serum of 88 preterm infants, aged from birth to 2 years, was determined by the high performance liquid chromatographic (HPLC) method using fluorescence detection. In 11 cases, patients were assayed for their tocopherol status in longitudinal studies, receiving known amounts of vitamin E supplements orally and/or parenterally. No correlation was found between serum alpha-tocopherol level and gestational age nor birth weight. All preterm infants receiving the vitamin E preparation showed an average serum tocopherol content of more than 0.5 mg/100 ml. The highest alpha-tocopherol concentration registered during vitamin E therapy was 3.28 mg/100 ml. Infusion of Intralipid, a product derived from fractionated soybean oil, caused a significant increase of gamma- and delta-tocopherol in blood serum. The half-life of delta-tocopherol in serum was calculated to be about 24 hours.

Vitamin A and E content of human milk at early stages of lactation

The influence of gestational age and lactational stage on carotene, retinol ester, alpha-tocopherol and gamma-tocopherol content of early human milk was studied. These nutrients were analyzed simultaneously using normal phase high-performance liquid chromatography. Serial samples of colostrum and early milk representative of complete early morning expressions were obtained during the first 6 weeks post-partum from mothers giving birth prematurely (PT) and at term (FT). Colostrum carotene content declined significantly during the first week of lactation. There was no apparent gestational age effect on milk carotene levels. The longitudinal pattern of change observed for milk retinol ester and alpha-tocopherol content was however, significantly different between PT and FT milk. Retinol ester levels were similar on days 1-2 postpartum reaching a maximal level on days 3-4 postpartum in FT milk. For PT milk the maximum retinol ester concentration occurred on days 6-7 postpartum. Retinol ester content decreased throughout lactation. The rate of decline was more marked for FT milk. The concentration of alpha-tocopherol in colostrum was higher in FT milk. On all subsequent days examined the level of alpha-tocopherol was greater in PT milk. For both FT and PT milk the alpha-tocopherol concentration was higher during the first week of lactation when compared with following weeks. gamma-Tocopherol levels were not influenced by gestational age or lactational stage. Levels of milk vitamin A and E did not appear to correlate with maternal intake. Colostrum levels of vitamin A and E may imply active sequestration by the mammary gland in compensation for limited placental transport. Early milk content of vitamin A and E appears to parallel mammary gland lipid synthesis.

Vitamin E status in preterm infants fed human milk or infant formula

Vitamin E status was assessed in 36 infants with birth weights less than 1500 gm who were assigned randomly to receive one of three sources of nutrition: milk obtained from mothers of preterm infants (preterm milk), mature human milk, or infant formula. Infants in each dietary group were further assigned randomly to receive iron supplementation (2 mg/kg/day) beginning at 2 weeks or to receive no iron supplementation. All infants received a standard multivitamin, providing 4.1 mg alpha-tocopherol daily. Serum vitamin E concentrations at 6 weeks were significantly related both to type of milk (P less than 0.0001) and to iron supplementation (P less than 0.05). Infants fed preterm milk had significantly higher serum vitamin E levels than did infants fed mature human milk, and both groups had significantly higher levels than did those fed formula. Ratios of serum vitamin E/total lipid were also significantly greater for infants fed human milks than for those fed formula. The addition of iron to all three diets resulted in significantly lower serum vitamin E levels at 6 weeks (P less than 0.05); however, only in the group fed formula was there evidence of vitamin E deficiency. Preterm milk with routine multivitamin supplementation uniformly resulted in vitamin E sufficiency in VLBW infants whether or not iron was administered.

Intestinal absorption of vitamin E in low birth weight infants

Intestinal absorption of dl-alpha-tocopheryl acetate was studied in low birth weight infants. Vitamin E was given from the first day of life, either as a water-soluble (Ephynal) or as a lipid-soluble preparation (E-vitamin). Serum-alpha-tocopherol concentrations were determined before treatment and on days three and seven. Treatment with both vitamin E preparations increased serum-alpha-tocopherol on day three and seven. The mean serum-alpha-tocopherol +/- SD on day seven were 41.4 +/- 10.7 mumol/l for the Ephynal group and 26.7 +/- 12.5 mumol/l for the E-vitamin group, this difference being statistically significant (p less than 0.025). Oral feeding seems to influence the absorption of tocopherol from E-vitamin, as the infants with the highest serum-alpha-tocopherol concentrations were those with the highest oral/total feeding ratios. In infants with birth weight less than 1 000 g treatment with 25 mg Ephynal/day was found to increase serum-alpha-tocopherol on day seven to 46.9 +/- 12.3 mumol/l (mean +/- SD). This concentration is comparable to those reported by others using higher doses of oral vitamin E.

The influence of dietary factors on the vitamin E requirements of the low birthweight infant

The vitamin E requirements for the low birthweight (LBW) infant varies with other dietary factors such as iron and polyunsaturated fatty acids (PUFA). This interaction is caused by the influence of iron on the oxidative breakdown of lipids (lipid peroxidation). Thus the need for fortification of infant formulas with vitamin E increases if the formulas are iron fortified or have a high content of PUFA. A vitamin E/linoleic acid ratio of greater than 1 IU/g is currently recommended. The formulas on sale in Sweden satisfies this recommendation. In breastmilk we found a vitamin E/linoleic acid ratio of greater than 1 IU/g in colostral and transitional milk. In mature breastmilk, however, 9 out of 24 samples showed a ratio less than 1 IU/g. Thus it is possible, that the LBW infant fed mature human milk may need a larger supplement of vitamin E than the formula fed infant.

Cell membrane maturation of Friend erythroleukemic cells and tocopherol-dependent erythropoietin effect: a scanning electron microscopic study

Typical morphological features of surface structural alterations during Friend cells differentiation are described. Scanning electron microscopy (SEM) revealed that DMSO induction switched on cell alteration of the proerythroblast-like cells, possessing microvilli projections on cell membrane with some ruffles, to an advanced stage with a blebby surface. This was followed by the formation of a pear-like polarized cell separated into two zones by a narrow cytoplasmic bridge at the equatorial plane. The polarized cells showed a smooth surface and tended to disconnect into two unequal cells. The villous leukemic erythroblast has negatively charged sialic acid residues on the glycocalyx, available for latex hydrazide probe binding, while the blebby and polarized cells lack it. Tocopherol added to culture medium of DMSO-induced erythroleukemic cells prevented the formation of blebs and the polarization phenomena, without affecting hemoglobin synthesis. The tocopherol-treated cells contain available negative charges for latex hydrazide binding similar to uninduced Friend cells. Erythropoietin potentiated a repolarization ability and morphological alteration capacity to the tocopherol-treated cells and this was accompanied by a loss of glycocalyx-negative charges. At these growth conditions erythyropoietin induced a dose-dependent proliferation effect.

Medicinal iron to low birth weight infants

Serum ferritin concentrations were measured during the first 6 months of life in 28 low birth weight infants (mean birth weight 1820 g range 900-2460; mean gestational age 34 weeks range 29-37) fed a standard formula fortified with ferrous sulphate. Fifteen of the infants received supplementary medicinal iron (ferrous succinate) from 3 weeks of age, and 13 only from 2 months of age. All were given vitamin E from 10 days of age. The serum ferritin values did not differ between the groups at 1-2 days, 8-10 weeks or at 6 months. Furthermore, there were no signs of hyperhaemolysis at 8-10 weeks in the group receiving medicinal iron early. The data indicate that the iron content in the formula is sufficient until 2 months of age, but also that thereis no disadvantage in starting medicinal iron at 3 weeks of age, if the diet is sufficient in vitamin E.