Reduced Erythrocyte Superoxide Dismutase Activity in Low Birth Weight Infants Given Iron Supplements

Abstract

ABSTRAU. Erythrocyte superoxide dismutase (ESOD) activity reflects copper utilization and the risk of copper deficiency. To investigate the possible effects of inorganic iron on the metabolism of copper in low birth weight infants, we have measured ESOD activities in three groups of infants receiving different iron supplements. Fifty-five low birth weight infants were randomly assigned to receive daily from 28 d either 13.8 mg (HiFe), 7 mg (MidFe), or no elemental iron (NatFe) as iron edetate. At 27 d, 8, 12, and 20 wk postnatal age, infants were weighed and measured and hematologic indices, plasma ferritin, zinc, and copper concentrations, and ESOD activities were assayed. Anthropometrical and hematologic indices and plasma copper and zinc concentrations did not differ among treatment groups at any time, but at 20 wk, plasma ferritin concentrations [(pg/L) mean; SD] were lower in the NatFe group (17; 2.0) than in the HiFe group (32; 1.9: 95% confidence interval for mean difference 6.6 to 22.0, p < 0.01). ESOD activities (U/g Hb) were similar in HiFe (1447; 263), MidFe (1552; 322), and NatFe (1538; 382) groups at 27 d, but by 20 wk activities in the HiFe group (1537; 211) were lower than in the MidFe (1789; 403: 95% confidence interval 38 to 466, p < 0.05) and NatFe (1858; 304: 95% confidence interval 150 to 492,p < 0.01) groups. The lower ESOD activities found in the HiFe group at 20 wk may reflect altered copper metabolism induced by the iron supplement, but the clinical importance of this observation is unknown. (Pediatr Res 29: 297-301,1991) Abbreviations ESOD, erythrocyte superoxide dismutase CI, confidence interval HiFe, high iron intake LBW, low birth weight MidFe, middle iron intake NatFe, natural iron intake SOD, superoxide dismutase RBC, red blood cell Because iron and copper have similar physicochemical properties, interactions can occur between them that can affect adversely the metabolism of copper (1). The practical relevance of this has been shown in mixed fed healthy infants in whom an iron-fortified (10.2 mg/L) formula achieved a lower intestinal absorption and whole body retention of copper than did the

Haematological effect of iron supplementation in breast fed term low birth weight infants

“…The earlier study in term SGA infants also reported similar findings. 10 Some preterm trials documented a significant improvement in serum ferritin, 13 whereas others had no significant change or did not estimate ferritin. 9 10 We did not document any benefit in anthropometry; the inadequate duration of follow up and small sample size however preclude any definite conclusions.…”

Lactoferrin in the Preterm Infants' Diet Attenuates Iron-Induced Oxidation Products

“…Although it is recommended that premature infants receive at least 2-4 mg/kg/d of iron to prevent iron deficiency anemia (25), high amounts of iron added to the diet have been shown to decrease serum ceruloplasmin (26) and copper-zinc SOD levels in erythrocytes (27). These effects may be the result of adverse effects on copper metabolism from excess iron.…”

Meeting the Iron Needs of Low and Very Low Birth Weight Infants

“…Similarly, Barclay et al [33] found no effect on hemoglobin of an iron intake of 3.6-6.8 mg/kg/day as compared to 1.0-1.6 mg/kg/day from 2 to 30 weeks postnatal age in infants with an average birth weight of 2,000 g. However, there was a lower erythrocyte superoxide dismutase activity in the high iron group, suggesting altered copper metabolism -a possible adverse effect of iron [33] .…”