Zinc Content in Breast Milk and Its Association with Maternal Diet

Abstract

Background: Zinc is an indispensable element, being involved in many biological processes. Correspondingly, insufficient zinc intake in early youth can detrimentally affect the function of a growing body. The aim of this study was to determine zinc content in breast milk among lactating women in Latvia and factors (maternal diet; mother’s and baby’s characteristics; breastfeeding pattern) affecting it. Methods: In total, 62 mature milk (at least one month postpartum) samples were collected and pooled within 24 h. Zinc content (mg 100 mL−1) was determined using inductively coupled plasma mass spectrometry (ICP-MS; Agilent 7700×, Agilent Technologies, Tokyo, Japan). Results: Zinc content in mature breast milk ranged from 0.01 to 0.34 mg 100 mL−1 with a median (interquartile range) content of 0.10 (0.05–0.15) mg 100 mL−1. Time postpartum was a significant negative predictor for zinc content in breast milk (r = −0.500; p = 0.000). Median maternal zinc intake was 10.70 (7.24–15.27) mg. Yet, zinc content in breast milk was unaffected by maternal dietary zinc intake (r = 0.155; p = 0.221). Conclusions: Maternal dietary zinc intake was nearly the recommended intake for lactating women (11 mg), but due to low zinc content in breast milk, babies in Latvia might not receive sufficient zinc intake. Future research should aim for the assessment of zinc status by evaluating plasma or serum levels of both mothers and babies.

Investigation of Iron and Zinc Concentrations in Human Milk in Correlation to Maternal Factors: An Observational Pilot Study in Poland

“…In our study, the majority of participants (63%, n = 20) did not reach the EAR value for zinc (10.4 mg/d). These results are consistent with previous studies that indicated that maternal dietary zinc intake was nearly or below the recommended values [ 38 , 39 , 40 ]. Data from several developing countries where zinc intake was presumed to be low (e.g., Bangladesh [ 53 ], Egypt [ 54 ], and Nigeria [ 55 ]), showed that HM zinc concentrations were relatively lower than those of well-nourished American women [ 56 ].…”

“…In our study, the concentration of HM iron (0.33 mg/L) was higher compared to mature milk from Swedish (0.29 mg/L [ 34 ]), Honduran (0.21 mg/L [ 36 ]), Indonesian (0.26 mg/L [ 37 ]), Thai (0.19 mg/L [ 38 ]), and lower than Vietnamese (0.59 mg/L [ 39 ]) and Iranian (0.89 mg/L [ 24 ]) mothers. Regarding zinc, in our study its median concentration (2.12 mg/L) was similar or slightly higher than that reported in other countries [ 37 , 38 , 39 , 40 ]. Some of the divergences between the findings for HM iron and zinc concentrations may be related to the fact that iron content in HM was reported to be higher at the nighttime feeding and in hindmilk samples [ 27 ].…”

Carotenoid Content in Breastmilk in the 3rd and 6th Month of Lactation and Its Associations with Maternal Dietary Intake and Anthropometric Characteristics

“…The content of some nutrients in breast milk is dependent on maternal dietary intake, including fatty acid profile [15], iodine [16] and vitamins B 1 , B 2 , B 6 and B 12 [17]. However, maternal dietary intake has a limited influence on breastmilk macronutrient composition [14] and some micronutrients, e.g., folic acid [17] and zinc [18]. Some studies have indicated that maternal nutritional status measured as body mass index (BMI) may influence the milk fat concentrations [14] as well as carotenoid concentrations [19].…”

Determining the Actual Zinc and Iron Intakes in Breastfed Infants: Protocol for a Longitudinal Observational Study (Preprint)

“…Zinc and iron concentrations in breast milk are high during early lactation and gradually decline thereafter [17][18][19]. The amounts of zinc and iron in breast milk consumed by infants after 6 months are lower than the estimated daily requirements [20,21]. The majority of zinc and iron intakes in infants during this period need to be provided by complementary foods.…”