[Effect of vitamin A supplements on iron metabolic homeostasis for preschoolers]

To explore the effect of vitamin A (VA) combined iron supplements on iron metabolic homeostasis for preschoolers.

About 445 preschoolers with aged 3-6 years old from eight kindergartens in Pixian county, Chengdu were recruited into this trial from March to September, 2011. All subjects met the inclusion criteria were randomly divided into four groups using random number table: sole VA supplementation group (VA group, a single oral dose of VA at about 200 000 units), sole iron supplementation group (FE group, daily oral supplementation with the element iron 1-2 mg·kg(-1)·d(-1) for five days a week, lasting for 6 months), the combined supplementation of VA and iron group (VF group) and control group (CO group, no VA and iron supplementation). The concentration of serum VA, serum ferritin (SF), serum transferring receptor (sTfR), C-reactive protein (CRP) and hemoglobin (Hb) were measured from 3 ml vein blood. The sTfR-SF index (TFR-F index) and total body iron content (TBIC) before and after intervention were calculated. The differences of these indexes between groups before and after intervention were analyzed.

The level of sTfR before intervention in VA group ((1.78 ± 0.17) mg/L) was significantly higher than that of after intervention ((1.18 ± 0.11)mg/L) (t = 28.88, P < 0.01). The levels of TFR-F index and TBIC in FE and VF groups before intervention ( (1.59 ± 0.37), (1.63 ± 0.40) and (9.04 ± 2.71), (9.26 ± 2.33) mg/kg, respectively) were all lower than those of after intervention (TFR-F index:(1.84 ± 0.51), (1.87 ± 0.45) and TBIC:(12.42 ± 3.49), (13.01 ± 2.98)mg/kg) (t values were 3.93, 3.78, 7.57 and 9.41, respectively, all P values were <0.01). The incidence of iron deficiency in VA, FE, and VF groups before intervention were 26% (25/95), 31% (30/98) and 31% (28/90) and were 41% (39/95), 10% (10/98) and 18% (16/90) for after intervention, respectively. The difference of this index in VA, FE and VF groups were significant (χ(2) values were 4.59, 12.50 and 4.31, respectively, all the P values were <0.05).

Combined VA and iron was as effective as VA alone or iron alone in decreasing the iron deficiency, the impact of VA intervention on iron metabolic homeostasis was mainly manifested in iron usage and mobilization, but showed no effect on total body iron content.