[Effects of vitamin A, vitamin A plus iron and multiple micronutrient-fortified seasoning powder on iron metabolic homeostasis].

OBJECTIVE: To evaluate the effect of vitamin A, vitamin A plus iron and "7 + 1" multiple micronutrient-fortified seasoning powder on iron metabolic homeostasis in preschool children.

METHODS: This was a randomized, controlled and blinded interventional field trial. A total of 226 2 - 7 years old preschool children were recruited from three nurseries in the area, and they were randomly assigned into three different fortified diet groups for 6 months. The subjects in Group I were fortified with vitamin A; those in Group II and III were fortified with vitamin A plus iron and vitamin A plus iron, thiamine, riboflavin, folic acid, niacinamide, zinc and calcium (7 + 1), respectively. The concentration of serum vitamin A was measured by high-performance liquid chromatography (HPLC), serum ferritin (SF) was measured by enzyme-linked immunosorbent assay (ELISA), soluble transferrin receptor (sTfR) was measured by microparticle-enhanced, and hemoglobin (HB) by hemiglobincyanide, the sTfR-SF index (TFR-F index) and total body iron content were computed respectively before and after intervention. Simultaneously, children's demographic data, socio-economic status and eating habits, etc. were investigated by questionnaires.

RESULTS: A total of 226 preschool children were included in the study with age ranged from 2 to 7 years with average age (4.0 ± 0.85) (means ± standard deviation). The prevalence of anemia, deficient iron storage, vitamin A deficiency (VAD) and suspect sub-clinical vitamin A deficiency (SSVAD) were 23.5%, 15.0%, 6.3% and 25.9%, respectively. The levels of SF and sTfR significantly decreased after intervention in all groups (χ(2) = 8.3298, χ(2) = 16.1471, χ(2) = 15.1371, χ(2) = 15.1171, χ(2) = 5.2617, χ(2) = 4.8844, P < 0.05) especially in group II and group III for SF (χ(2) = 16.1471, χ(2) = 15.1371, P < 0.05) and group I for sTfR (χ(2) = 15.1171, P < 0.05). No marked change of TFR-F index and total body iron contents was observed in group I (t = 0.1817, t = 1.7736, P > 0.05), while TFR-F index decreased and total body iron contents increased in group II and group III (t = 5.3561, t = 6.5979, t = 11.1663, t = 8.7306, P < 0.05) after intervention.

CONCLUSION: Vitamin A intervention has significant effect on iron storage and mobilization but seldom effect on iron absorption in small intestine. The combination of vitamin A and other micronutrients might be a better intervention for the improvement of iron deficiency for preschool-children.