Adjustments in zinc absorption and endogenous excretion maintain zinc homeostasis in nonpregnant adults fed lowzinc diets. The effects on zinc homeostasis of a low zinc intake during pregnancy and lactation have not been described in a longitudinal study. Objective: We examined longitudinal changes in fractional zinc absorption (FZA) and zinc kinetics in 10 healthy Brazilian women who habitually consumed a marginal zinc diet (Ȃ9 mg Zn/d). Design: Zinc status was measured at 10 -12 (early

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... cy; EP) and 34 -36 (late pregnancy; LP) wk of pregnancy and at 7-8 wk after delivery (early lactation; EL). Zinc kinetics and FZA were studied by using stable isotopic tracers. Results: Zinc intake averaged 9 Ȁ 3 mg/d throughout the study. FZA increased from 29 Ȁ 6% at EP to 43 Ȁ 10% at LP and to 39 Ȁ 13% at EL (P 0.05). FZA was inversely related to plasma zinc at EL (r ҃ Ҁ0.73, P ҃ 0.02) and LP (r ҃ Ҁ0.72, P ҃ 0.07). Plasma zinc mass was 23% greater at LP than at EP or EL (P 0.05). The amount of zinc (mg/d) that fluxed between plasma and the most-rapidlyturning-over extravascular pool was 53% greater at LP than at EP or EL (P 0.05). The zinc flux between plasma and the less-rapidlyturning-over zinc pool at EL was 27% greater than that at EP or LP, but this difference was not significant. Conclusions: FZA increased significantly in women with marginal zinc intakes during pregnancy and lactation; the increase was higher in women with low plasma zinc. Plasma zinc was distributed into a different exchangeable pool at LP than at EL. Am J Clin Nutr 2005;82:118 -24.