Human milk proteins differentiate over the sex of newborns and across stages of lactation.

BACKGROUND & AIMS: Human milk (HM) is a complete food that meets the nutritional and energy demands of the newborns. It contains numerous bioactive components, including functional proteins. Variations in HM energy and lipid content have already been reported related to the newborn's sex, but differences between protein profiles are still scarce. This work aimed to identify differences between HM proteins produced by mothers of female and male newborns, in the lactation stages of colostrum and mature milk, and the metabolic pathways involved. METHODS: A total of 98 HM samples were collected from 39 lactating women and classified according to the newborn's sex, stages of lactation, and three mothers' age groups, and evaluated about protein concentration and one-dimensional electrophoretic profile. Next, to assess samples with the greatest differences, the HM proteins regarding the newborn's sex and the stages of lactation were compared using nano-LC-MS/MS, in 24 HM samples randomly rearranged into four groups: female and male infants, and colostrum and mature milk. Functional classification, metabolic pathways, and protein interaction networks were analyzed by Gene Ontology, KEGG, and STRING, respectively. RESULTS: The soluble protein content of HM decreased throughout lactation, with differences regarding isolated factors, such as mothers' age group, child's sex and stages of lactation, and also in terms of their interactions. A total of 146 proteins were identified, 42 of which showed different abundances over the sexes of newborns and 53 between the stages of lactation. In general, proteins related to metabolic processes were up-regulated for mothers of male infants and in the mature stage of lactation, while proteins related to defense were up-regulated in mothers of female infants and in the colostrum phase. CONCLUSION: This study indicated that there are differentiated and specific nutritional and defense needs of newborns, by sex and by lactation phase, which is highly relevant for a more appropriate supply of food to infants receiving HM from donor mothers.

Iodine Concentration in Brazilian Drinking Water and Its Possible Contribution to Iodine Intake for Different Physiological Groups.

Objective: The objective is to analyze the concentration of iodine in Brazilian drinking water and its possible contribution to iodine intake for different groups. Methods: Water samples collected from primary healthcare units in eight locations distributed across all five macroregions of Brazil were analyzed. The quantification of iodine in the water samples was done by spectrophotometry (leuco crystal violet method). To classify the degree of iodine concentration, the recommendation of the Ministry of Health (China) was followed since Brazil lacks a classification standard. To verify the possible contribution of drinking water to iodine intake for different groups, the recommended water intake for each group according to the United States Institute of Medicine (2004) was considered. The percentage of iodine in drinking water and its contribution to iodine intake for different physiological groups were calculated based on the estimated average requirement (EAR) of iodine. A descriptive statistical analysis was performed using SPSS version 21.0 and Statistical Analysis Systems (SAS) version 9.2. Results: Significant differences were found between the maximum and minimum concentrations of iodine in water samples from the same location. In Pinhais (south region), the difference was 44.32 µg· L-1; in Viçosa (southeast region), it was 27.86 µg·L-1; in Rondonópolis (midwest region), it was 12.66 µg·L-1; in São Luís (northeast region), it was 11.82 µg·L-1; in Brasilian Federal District (midwest region), it was 10.98 µg·L-1; in Macaé (southeast region), it was 10.14 µg· L-1; in Palmas (north region), it was 4.22 µg·L-1; and in Vitória (southeast region), it was 1.69 µg·L-1. The maximum concentrations of iodine found in the drinking water of Pinhais and Viçosa can contribute more than 70.0% and 50.0%, respectively, to daily iodine intake for all groups. Conclusion: Monitoring the concentration of iodine in drinking water from different locations in each city or Federal District is a preventive measure against inadequate iodine intake and possible adverse changes in population health.