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 microg/l and Hb > or = 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 < or = 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 < or = 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.