Evaluation of the iron, antioxidant and dietary status of iron supplemented breastfed healthy infants

Harding, Scott V. (2003) Evaluation of the iron, antioxidant and dietary status of iron supplemented breastfed healthy infants. Masters thesis, Memorial University of Newfoundland.

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Abstract

It is known that 10 - 28% of breast fed infants will develop iron deficiency (ID; serum ferritin ≤ 12 μg/L or Hgb ≤ 110 g/L + Hct ≤ 33% or MCV ≤ 75 fL) by 6 months of age. Iron deficiency anaemia will effect 10 -15% of the exclusively breast fed population by 6-months of age (IDA; Hgb ≤ 110 g/L + serum ferritin ≤ 12μg/L or Hct ≤ 33% and MCV ≤ 75 fL). ID severe enough to cause anaemia has been proven to be a factor in delayed cognitive and psychomotor development. We initiated a randomized double blind clinical trial to investigate the effects of supplementing breast fed infants with iron and its effects on the incidence of ID and IDA (7.5 mg FeSO₄/day). Supplementation was between 1 to 6-month, to a maximum of 150 days. Further investigation into whether the supplement had any adverse effects on the antioxidant status, potential for oxidative damage and mineral absorption of the infants was also carried out. Our findings have shown that ID can affect as high as 55% of infants (p<0.02). Iron supplementation, 7.5 mg FeSO₄/day, is high enough to demonstrate a difference in the haemoglobin concentrations (124+/-9.13 g/L vs. 116+/-6.68 g/L), hematocrit (0.352+/-0.029 vs. 0.333+/-0,019) and MCV (81.17+/-4.13 fL vs. 77.22+/-3.89 fL) compared to infants whom are not supplemented (p<0.05). While plasma ferritin concentrations did not differ between the two groups the infants receiving placebo had a significantly higher rate of decline in ferritin stores between 1 and 3.5 months than did infants who were supplemented (-82+/-54 μg/L vs. -139+/-84 μg/L). This level of iron supplementation does not appear to affect the antioxidant response of erythrocyte superoxide dismutase or catalase nor does it change the total antioxidant power of the infant plasma (FRAP). Plasma mineral concentrations were normal for all infants but plasma zinc concentrations significantly increased between the 3.5 and 6-month blood samples (p<0.05), with not enough data to explain. Positive correlations exist between the infant 1-month haemoglobin and 3.5 and 6-month plasma ferritin concentrations, which may prove useful as a predictor of iron stores for infants who are exclusively breast fed. Breast milk iron concentrations were measured at 1 and 3.5-months (0.47+/-0.14 mg/L to 0.76+/-0.40 mg/L at 1-month; 0.29+/-0.13 mg/L to 0.78+/-0.36 mg/L at 3.5-months) by three separate techniques, direct GFAAS, methods of addition GFAAS and FAAS. While all three methods produced values that are in the reported range for human breast milk iron concentrations the direct GFAAS seems to have been validated by reports in literature and the methods of addition GFAAS as a simple, sensitive and reliable technique. Maternal haemoglobin at delivery was also examined as a predictor of breast milk concentrations and infant haemoglobin at 1-month but no relationships were seen between these variables. In all it appears that iron supplementation (7.5 mg Fe/Day) will improve the iron status of exclusively breast-fed infants without risk of impaired mineral absorption or oxidative damage. The iron status of exclusively breast-fed infants appears to be poor. There is a need for better screening or supplementation of these infants in order to prevent this deficiency.

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