Iron and Zinc Status in Thai Lactating Women and the Concentrations in Their Breast Milk During the First 6 Months of Lactation

Abstract

BackgroundBreast milk is the gold standard of infant feeding especially during the first 6 months of life. Nutritional status and dietary intake of lactating women may affect breast milk concentration of iron (Fe) and zinc (Zn).ObjectiveTo assess the status of Fe and Zn as well as their concentrations in breast milk of lactating women during the first 6 months of lactation, and to determine factors associated with Fe and Zn status in breast milk of lactating women.DesignThis was a longitudinal study over a 6‐month period. Lactating women were enrolled when visiting a well child clinic at Faculty of Medicine Ramathibodi Hospital. Maternal intakes of dietary Fe and Zn, anthropometry, and breast milk Fe and Zn concentrations were determined at 2, 4 and 6 months of lactation. Complete blood count, Fe status using serum ferritin, and plasma Zn levels of the women were analyzed at 6 months of lactation.ResultsThere were 63 lactating women. The prevalence of Fe depletion (serum ferritin <12 ug/dL), Fe deficiency anemia (Hb <110 g/L) and Zn deficiency (plasma Zn <10.7 umol/L) were 4.8%, 3.2%, and 17.5%, respectively. The medians of dietary Fe and Zn intakes at 6 months were 8.67 and 5.04 mg, respectively. At 2, 4, and 6 months of lactation, the median levels of Fe in breast milk were 0.16, 0.13, and 0.13 mcg/L, while Zn levels were 1.1, 0.72, and 0.54 mcg/L, respectively. Breast milk Fe and Zn levels were significantly different between each period of lactation. At 6 months, Fe status was positively correlated with dietary Fe intake (b=0.515, p=0.018) and Fe levels in breast milk were inversely correlated with plasma Zn levels (b=−0.101, p=0.01).ConclusionThere were deficiencies of Fe and Zn during the first 6 months of lactation.Breast milk Fe and Zn concentrations were decreased during the lactation period. Nutrients in breast milk were affected by maternal nutritional status. Appropriate dietary intakes of lactating mothers should be advised and monitored.