Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values for zinc, using a two-stage factorial approach and reference values for body weight. The first stage of estimating physiological requirements used studies that had physiologically plausible data, specifically related to faecal excretion of endogenous zinc. Adult physiological requirements were closely related to body size, and sex differences were not detectable after adjustment for body weight. Average Requirements (ARs) for dietary zinc necessary to meet physiological requirements were estimated using saturation response modelling, taking into account the inhibitory effect of dietary phytate on zinc absorption. Estimated ARs and Population Reference Intakes (PRIs) are provided for phytate intake levels of 300, 600, 900 and 1 200 mg/day, which cover the range of mean/median intakes observed in European populations. ARs range from 6.2 to 10.2 mg/day for women with a reference weight of 58.5 kg and from 7.5 to 12.7 mg/day for men with a reference weight of 68.1 kg. PRIs were derived from the zinc requirement of individuals with a body weight at the 97.5 th percentile for reference weights for men and women and range from 7.5 to 12.7 mg/day for women and from 9.4 to 16.3 mg/day for men. ARs for infants from seven months of age and for children were estimated factorially, based on extrapolation from estimates of adult losses plus zinc needs for growth, and range from 2.4 to 11.8 mg/day. PRIs for infants and children were derived by assuming a coefficient of variation of 10 %, and range from 2.9 to 14.2 mg/day. For pregnancy and lactation, additional zinc requirements related to fetal and maternal tissues and transfer of zinc into breast milk, respectively, were considered and additional PRIs of 1.6 and 2.9 mg/day, respectively, were estimated. © European Food Safety Authority, 2014

Scientific Opinion on Dietary Reference Values for zinc

Overview of Nutrients in Human Milk.

Toxic and essential trace elements in human milk from Greek lactating women: association with dietary habits and other factors.

Human milk is considered to be the ideal food for infants. Accurate, representative, and up-to-date nutrient composition data of human milk are crucial for the management of infant feeding, assessment of infant and maternal nutritional needs, and as a guide for developing infant formula. Currently in the United States, the nutrient profiles of human milk can be found in the USDA National Nutrient Database for Standard Reference, and in books or review articles. Nonetheless, these resources all suffer major drawbacks, such as being outdated, incomplete profiles, limited sources of data, and uncertain data quality. Furthermore, no nutrient profile was developed specifically for the US population. The purposes of this review were to summarize the current knowledge of human milk nutrient composition from studies conducted in the United States and Canada, and to identify the knowledge gaps and research needs. The literature review was conducted to cover the years 1980-2017, and 28 research papers were found containing original data on macronutrients and micronutrients. Most of these 28 studies were published before 1990 and mainly examined samples from small groups of generally healthy lactating women. The experimental designs, including sampling, storage, and analytic methods, varied substantially between the different studies. Data of several components from these 28 studies showed some consistency for 1-6 mo postpartum, especially for protein, fat, lactose, energy, and certain minerals (e.g., calcium). The data for 7-12 mo postpartum and for other nutrients are very scarce. Comprehensive studies are required to provide current and complete nutrient information on human milk in the United States.

Human Milk Nutrient Composition in the United States: Current Knowledge, Challenges, and Research Needs.

Human Milk (HM) is the best source for newborn nutrition until at least six months; it exerts anti-inflammatory and anti-infective functions, promotes immune system formation and supports organ development. Breastfeeding could also protect from obesity, diabetes and cardiovascular disease. Furthermore, human colostrum (HC) presents a peculiar role in newborn support as a protective effect against allergic and chronic diseases, in addition to long-term metabolic benefits. In this review, we discuss the recent literature regarding "omics" technologies and growth factors (GF) in HC and the effects of pasteurization on its composition. Our aim was to provide new evidence in terms of transcriptomics, proteomics, metabolomics, and microbiomics, also in relation to maternal metabolic diseases and/or fetal anomalies and to underline the functions of GF. Since HC results are so precious, particularly for the vulnerable pre-terms category, we also discuss the importance of HM pasteurization to ensure donated HC even to neonates whose mothers are unable to provide. To the best of our knowledge, this is the first review analyzing in detail the molecular pattern, microbiota, bioactive factors, and dynamic profile of HC, finding clinical correlations of such mediators with their possible in vivo effects and with the consequent impact on neonatal outcomes.

https://www.mdpi.com/2072-6643/9/8/843/pdf

“Omics” in Human Colostrum and Mature Milk: Looking to Old Data with New Eyes

The aim of this study was to establish the possible effects of the sampling protocol (between-breast, within-feed, and diurnal differences) and the mother's personal factors (age, parity, iron supplementation, smoking habits, and lactation period) on the copper, iron, and zinc contents in human milk. One hundred thirty-six human milk samples identified by their origin and sampling conditions were analyzed. The samples were obtained from the 2nd to 15th d postpartum from 62 women. The data on the individuals required for the study were available. Mineral determinations were analyzed by flame atomic absorption spectrometry following a standardized protocol. The results showed that iron contents were higher in hind-milk samples and at the nighttime feeding and depended on the breast from which the sample was taken. The copper and zinc concentrations showed no significant variations. There was no significant relationship among the mothers' age, parity, smoking habits, iron supplementation, and copper content. Milk from older women had lower zinc contents than that of younger women. Increased amounts of iron were found in multiparous women. Between colostrum and transitional milk, a sharp decrease in zinc content was observed, whereas copper and iron contents remained constant. All of these results make it clear that standardized sampling protocols are needed in order to obtain comparable values.

A Molina

Papers

A study of factors that may influence the determination of copper, iron, and zinc in human milk during sampling and in sample individuals.