Zinc levels in maternal milk: the influence of nutritional status with respect to zinc during the third trimester of pregnancy

Abstract

Objective: To study the relationship between nutritional status with respect to zinc during the third trimester of pregnancy and levels of the same mineral in transition milk (days 13 and 14 of lactation) and mature milk (day 40 of lactation). Design: Longitudinal study. Subjects: A group of 57 healthy, lactating mothers aged between 18 and 35 y (27 AE 3.7) whose pregnancy and labour were attended by the Department of Obstetrics and Gynaecology of Cuenca INSALUD Hospital, Spain. Interventions: Zinc intake during the third trimester was determined by recording the consumption of foods over a ®ve day period and by registering zinc provided by dietary supplements. Zinc levels in maternal serum during this stage of pregnancy, and in transition and mature milk, were determined by atomic absorption spectroscopy. Results: During pregnancy all subjects showed zinc intakes lower than those recommended. Only one pregnant subject took a supplement that provided extra zinc (1 mgad). Subjects with an intake of lower than 50% of that recommended (L) (43.9%) showed signi®cantly lower serum and mature milk zinc levels than did those with higher intakes (H) (56.1%) [12.0 AE 1.5 mmolaL and 28.7 AE 6.2 mmolaL compared to 13.3 AE 2.6 mmolaL and 33.1 AE 8.0 mmolaL respectively]. 56% of L subjects and 28.6% of H subjects showed serum zinc levels of less than 12.2 mmolaL. 8% of L subjects and no H subjects showed less than 11.5 mmolaL of zinc in maternal milk. Conclusions: The diet conditions maternal serum zinc levels during pregnancy and those of milk during lactation. Though all subjects showed intakes clearly below those recommended, low levels in serum or milk were much rarer. These results support the idea that there is a need to reset the limits of normality for serum and milk zinc levels. Further work in this area may con®rm that the present recommended intakes of zinc be modi®ed. Sponsporship: This work was supported by the Fondo de Investigaciones Sanitarias de la Seguridad Social (FISss).

Food Components and Dietary Patterns of Two Different Groups of Mexican Lactating Women

“…Although zinc intakes of women in our study were lower than the recommendation, mean values were comparable to those reported by other authors in different populations [22,23]. In addition to total amount of zinc, it is important to consider bioavailability; in Mexican diets the availability of zinc (measured as solubility) was poor [24].…”

Effect of daily and weekly micronutrient supplementation on micronutrient deficiencies and growth in young Vietnamese children

“…Supplementation with vitamin A would reduce morbidity and mortality. Such a combined iron-zinc-vitamin A supplementation would probably have to be started at 4-6 mo of age, or even earlier when mothers are malnourished (42,43). The results of our study suggest that supplementation would not need to be done daily but that a once-weekly supplement would be sufficient for reducing anemia and improving zinc and vitamin A status.…”

Maternal Zinc Intakes and Homeostatic Adjustments during Pregnancy and Lactation

“…It is possible that the homeostatic adjustments during pregnancy reflect the mother’s zinc status prior to conception and that the lactation adjustments reflect zinc status during pregnancy. In a study of lactating Spanish women, maternal zinc intake during late pregnancy influenced mature milk zinc concentrations [83]. This continuum needs further study.…”