Influence of an iron intervention on the zinc status of young adult New Zealand women with mild iron deficiency

Interventions to combat mild Fe deficiency in women of childbearing age may affect Zn nutriture. We used dietary and laboratory indices to assess change in Zn status during a 4-month partially blinded placebo-controlled Fe intervention in women with low Fe stores (serum ferritin < 20 mu g/l and Hb >= 120 g/l) from Dunedin, New Zealand. Subjects aged 18-40 years were randomly assigned to three groups: dietary advice (diet group; DG; n 29), daily Fe supplement with meals (supplement group; SG; n 23; 50 mg Fe as amino acid chelate) and placebo (placebo group; PG, n 26). A validated semi-quantitative FFQ (SFFQ) was administered at baseline, and at 4, 8 and 15 weeks; fasting morning blood samples were assayed for serum Zn, alkaline phosphatase (ALP) and C-reactive protein at baseline, and at 4, 8, 12 and 16 weeks; hair Zn and taste detection thresholds by electrogustometry were measured at baseline and at 16 weeks. Intakes of flesh foods and vitamin C but not Zn or Fe increased, whereas phytate and phytate: Zn molar ratios decreased (all P <= 0.01) in the DG compared with the PG and SG, based on three SFFQ. Serum Zn increased in both the DG and PG (adjusted, P <= 0.002), so the between-group difference was not significant; the lack of a parallel rise in the SG was significant when compared with the PG (P=0.02). ALP activity (but not hair Zn or taste acuity) followed a similar trend. In conclusion, Zn status was not improved compared with placebo by an Fe-based dietary intervention. However, a daily moderate-dose Fe supplement with meals appeared to lower Zn status in these young adult women.