Introduction to Current Knowledge on Micronutrients in Human Milk: Adequacy, Analysis, and Need for Research

Human milk macro- and trace-elements: Simultaneous analysis in sub-milliliter amounts by ICP-MS and application to assessing acute supplementation effects

Adequate concentrations of human milk (HM) nutrients, including macro- and trace-elements, are essential for healthy growth and development of exclusively breastfed (EBF) infants. To monitor potential risk of deficiencies, and evaluate the effects of interventions like supplementation, accurate analysis is crucial. Even recent methods reporting on HM macro- and/or trace-elements describe multiple methodological approaches and the need for several milliliters. We optimized and validated a comprehensive method for simultaneous analysis of 13 macro- and trace-elements for simultaneous analysis by inductively-coupled plasma-mass spectrometry. 100-600 μL HM were microwave digested with ≤1.5 mL HNO3 (70 %). The digest was diluted to 5 % final acid concentration. He-Kinetic Energy Discrimination (KED; Na, K, P, Ca, Mg, Fe, Cu, Zn, Cr, Mo) and O2-Dynamic Reaction Cell (DRC; As, Mn, Se) modes minimized remaining interferences. Accuracy (NIST SRM 1869 infant formula; n = 15, 4 weeks) varied from 93.2 to 103 % (CV: 2.8-8.5 %) with trueness ranging from 93.9 to 104 %. Inter-day variation of a HM-pool (n = 20, 3 weeks) varied between 4.1 and 8.5 % for most elements; Cr, Mo, Mn (all<5 μg L-1) had higher variation, up to 25 %. Analyzing HM from 18 Bangladeshi mothers (2-4 months postpartum; day 1 = baseline, n = 17; day 2/3 = supplementation, n = 21 each) revealed higher concentrations for P, Ca, and Zn post-supplementation (p < 0.05, Friedman's Chi-Square Test). Na, Mg, Zn, and Se had the highest number of samples (>80 %) with concentrations below the Adequate Intake. Our method allows for simultaneous and reproducible analysis of macro- and trace-elements with concentrations ranging over 6 orders of magnitude, without the need for separate analytics and sample preparations, and requiring only sub-milliliter amounts of HM. Additional elements may be included after optimization and validation. The results from Bangladeshi HM samples indicate selective supplementation effects and concerningly low concentrations for some elements, which could adversely affect the EBF infant.

Understanding delays in the introduction of complementary foods in rural Ethiopia

Age-appropriate breastfeeding and introduction to complementary foods can shape child feeding practices, ensure adequate energy and nutrient intake and prevent linear growth faltering. This study aimed to assess mothers' and health workers' knowledge of timely introduction to complementary foods and evaluate the relationship between delays in complementary feeding and subsequent linear growth. We conducted two rounds of surveys (March/August 2017) among 249 health workers (n = 249) and caregivers (n = 2635) of children 6-23 months of age. We collected information about socio-demographic characteristics, knowledge and practice related to timely introduction to complementary foods. The study was conducted in households from the Productive Safety Net Programme (PSNP) districts, in four highland regions of Ethiopia. Delays in the introduction to complementary feeding were widespread with 53% of children 6-8 months of age not consuming solid, semisolid or soft foods in the past 24 h. After controlling for child, caregiver and household characteristics, children not introduced to complementary foods by 6-8 months had a 0.48 SD lower length-for-age z-score at 12-15 months. Caregivers' knowledge was strongly and inversely correlated with untimely introduction of complementary foods in logistic regressions (OR = 0.55, p < 0.01). In turn, local health extension worker's knowledge was strongly correlated with caregiver's knowledge. Consequently, frequent and timely visits by health extension workers emphasising not only on what to feed but also when and how to feed a child are needed. Innovative ways of increasing reach, intensity and frequency of nutrition messaging by using the PSNP interactions as an additional point of contact would need to be explored further.

Nutritional Status of Breastfeeding Mothers and Impact of Diet and Dietary Supplementation: A Narrative Review

Adequate nutrition during breastfeeding is crucial for ensuring the good health of mothers and babies. Despite the high energy and nutrient demands of breastfeeding, lactating women are often vulnerable from a nutritional perspective. The nutritional focus during breastfeeding tends to be on the newborn, often neglecting the mother's diet. Therefore, in the present narrative review, nutrient intakes were compared with the dietary reference values (DRVs) proposed by the European Food Safety Authority (EFSA) as well as by the World Health Organization/Food and Agriculture Organization (WHO/FAO). In the diets of lactating mothers, dietary inadequacies were observed in the intake of some vitamins, such as folic acid, vitamin B12, vitamin A, and vitamin D, and in the intake of certain minerals like calcium, iron, and iodine; polyunsaturated omega-3 fatty acid deficiencies, primarily in eicosapentaenoic acid and docosahexaenoic acid, were also observed. On the other hand, the debate on the necessity of supplementation during lactation continues; the need for nutritional supplementation during lactation depends on many factors, such us mothers' eating habits. There seems to be a positive association between nutritional supplementation of the lactating mother and the concentration of certain nutrients in human milk. The present narrative review provides an update on the nutritional status (fatty acids and micronutrients) of breastfeeding mothers and the impact of diet and dietary supplementation on human milk composition.

Assessment of nutrient adequacy and associated factors among lactating women of rural Bangladesh using observed intake: Findings from Bangladesh Integrated Household Survey 2018-2019

Lactating women of low- and middle-income countries are prone to develop deficiencies in essential nutrients due to various demographic and socioeconomic components. This study aimed to estimate the adequacy of dietary intake and the determinants of diet quality of lactating women in rural Bangladesh. One-day dietary recall (24-Hour recall) data of 973 lactating women were obtained from the Bangladesh Integrated Household Survey (BIHS) 2018-2019. Nutrient adequacy was determined using the Estimated Average Requirement (EAR) cut-point approach. The molar ratios of phytate to zinc, calcium, and iron were calculated. Mean Adequacy Ratio (MAR) was calculated to measure diet quality, and multiple linear regression analysis was performed to assess the sociodemographic determinants of MAR. While the intakes of protein and carbohydrate were equal to/above the Acceptable Macronutrient Distribution Range (AMDR) among most of the subjects, intakes of total energy and fat were below the reference intakes for 74.4% and 98.3%, respectively. Nutrient adequacy remained unmet for riboflavin, calcium, vitamin A, and folate among most (87.2%-97.6%) of the study population, and the mean (SD) MAR was 0.72 (0.12). Cereals were the major contributor of energy and B vitamins, while protein and iron mainly came from plant-based sources. The molar ratio of phytate to iron was greater than the critical limit among most respondents. Maternal Body Mass Index (BMI) (beta = 0.003, p = .014) and education level (beta = 0.017, p = .038) were associated with their diet quality. The diet of most lactating women in rural Bangladesh indicates the inadequacy of several micronutrients. This can lead to a worsening of the double burden of malnutrition in women. Lactating women should be given special consideration when designing food and nutrition programs for reproductive women in rural Bangladesh.

Development of a Compartmental Model for Studying Vitamin A Kinetics and Status in Theoretical Lactating Women

BACKGROUND

Low vitamin A status and suboptimal milk vitamin A concentrations are problems in many populations worldwide. However, limited research has been done on whole-body vitamin A kinetics in women of reproductive age, especially during lactation.

OBJECTIVES

Goals were to develop compartmental models describing retinol kinetics in theoretical nonlactating (NL) and lactating (L) women and to determine whether the retinol isotope dilution (RID) method accurately predicted vitamin A total body stores (TBS) in the groups and individuals.

METHODS

We adapted 12 previously-used theoretical females with assigned values for retinol kinetic parameters and TBS (225-1348 μmol); subjects were NL or L (nursing one 3- to 6-mo-old infant) during 49-d kinetic studies after isotope dosing. We used an established compartmental model, adding a compartment for chylomicrons and, for L, another for mammary gland milk with inputs from holo-retinol-binding protein and chylomicron retinyl esters and output to milk. Using compartmental analysis, we simulated tracer responses in compartments of interest and calculated TBS using the RID equation TBS =   FaS/SAp [Fa, fraction of dose in stores; S, retinol specific activity in plasma/specific activity in stores; SAp, specific activity of retinol in plasma].

RESULTS

Models for both groups were well identified. Simulated plasma tracer responses were similar for NL and L, with L always below NL; milk tracer paralleled plasma from 10 d postdosing. Geometric mean FaS ratios (L/NL) were ∼0.75 during days 2-30. Using appropriate group FaS, RID provided accurate TBS predictions for >80% of NL and L subjects after day 18 when CV% for FaS was ∼10%.

CONCLUSIONS

These new physiologically-based models for vitamin A kinetics may be useful for future research in women of reproductive age. Results indicate that, in groups like these, RID to assess an individual's vitamin A status should be done at 21-28 d after isotope dosing.

B-Vitamins and Choline in Human Milk Are Not Impacted by a Preconception Lipid-Based Nutrient Supplement, but Differ Among Three Low-to-Middle Income Settings-Findings From the Women First Trial

Introduction: Optimal human milk (HM) B-vitamin concentrations remain undefined, especially in areas where undernutrition is prevalent. The impact of supplementation pre-conception through pregnancy on HM B-vitamin composition remains unknown.

Methods: Human milk (HM) was collected at 2-weeks postpartum from 200 women in Guatemala, India, and Pakistan (the Women First Trial). The women were randomized to start a lipid-based nutrient supplement before conception, at end of the first trimester, or not at all; intervention continued until delivery. HM concentrations of eight B-vitamins and choline were assessed via ultra-performance liquid chromatography-tandem mass spectrometry. Maternal diet was assessed in early pregnancy, and infant growth followed through 6 months post-delivery.

Results: Despite supplement exposure averaging 15.7 (pre-conception arm) and 6.0 months (prenatal arm), HM B-vitamins did not differ between arms, but site differences were evident. Guatemala had higher HM concentrations of vitamin B3 than Pakistan and India. Pakistan had higher HM concentrations of thiamin and vitamin B6 than India and Guatemala. Cohort average HM vitamin B2 (162 ± 79 μg/L) and B6 (31.8 ± 24.6 μg/L) fell below values defined as deficient in 81.5 and 85.5% of samples, potentially reflecting sampling procedures and timing. Maternal dietary intakes of only vitamin B6 and choline were associated with the corresponding concentrations in HM (p < 0.005). No HM B-vitamin concentrations were associated with infant growth.

Conclusion: Prenatal supplementation for at least 6 months had no impact on HM B-vitamin concentrations at 2-weeks postpartum. Results suggest that the adequacy of HM composition was generally maintained, with potential exceptions of vitamin B2 and B6.

Macro- and Trace-Element Intake from Human Milk in Australian Infants: Inadequacy with Respect to National Recommendations

Longitudinal variations of macro- and trace elements in human milk (HM) are not well characterised, and therefore, the recommendations for intake for Australian infants require more evidence to ensure accuracy. We aimed to investigate the longitudinal variation of HM macro- and trace-element concentrations (1-12 months) and infant intake (1-6 months) and to investigate the relationships between intake and infant growth parameters at 3 and 6 months, and determine if intake was sufficient when compared to national guidelines. HM samples were collected monthly for the first 6 months and then at 9 and 12 months postpartum from mother-infant dyads (n = 83). Test-weighing was used to determine the volume of HM consumed daily. Element concentrations (Na, Ca, K, Mg, P, I, Se, Zn, Cu, Mn, Mo, and Fe) were measured using ICP-MS, and intake was calculated using the measured concentrations and the volume of HM consumed. The average intake of HM was 776.3 ± 24.0 mL for the infants. Changes in concentration from months 1 to 12 postpartum were observed for all the measured micronutrients (all p < 0.05). The calculated intakes of all the macro- and trace elements showed that 0% to 82% of infants met the current adequate recommendations at varying periods of lactation. The calculated macro- and trace-element intakes were below the adequate intake recommendations, suggesting that they are not reflective of healthy infant requirements. These findings suggest the need for larger studies using sensitive analytical techniques and the revision of current recommendations for breastfed infants.

The Mothers, Infants, and Lactation Quality (MILQ) Study: A Multi-Center Collaboration

Little valid information is available on human milk nutrient concentrations, especially for micronutrients (MNs), and there are no valid reference values (RVs) across lactation. In this multi-center collaborative study, RVs will be established for human milk nutrients across the first 8.5 mo postpartum. Well-nourished, unsupplemented women in Bangladesh, Brazil, Denmark, and The Gambia (n = 250/site) were recruited during the third trimester of pregnancy. Milk, blood, saliva, urine, and stool samples from mothers and their infants are collected identically at 3 visits (1-3.49, 3.5-5.99, 6.0-8.49 mo postpartum). Milk analyses include macronutrients, selected vitamins, trace elements and minerals, iodine, metabolomics, amino acids, human milk oligosaccharides, and bioactive peptides. We measure milk volume; maternal and infant diets, anthropometry, and morbidity; infant development, maternal genome, and the infant and maternal microbiome. RVs will be constructed based on methods for the WHO Child Growth Standards and the Intergrowth-21st Project. This trial was registered at clinical trials.gov as NCT03254329.

Differences in Micronutrient Intakes of Exclusive and Partially Breastfed Indonesian Infants from Resource-Poor Households are Not Accompanied by Differences in Micronutrient Status, Morbidity, or Growth

BACKGROUND

When maternal micronutrient intakes and statuses are compromised, reductions in micronutrient concentrations in neonatal stores and human milk may result in suboptimal micronutrient intakes, statuses, and functional outcomes of breastfed infants during the critical first 6-month period.

OBJECTIVES

We compared the adequacy of micronutrient intakes and statuses at 2 and/or 5 months and morbidity and growth faltering at 2, 5, and 12 months in a cohort of exclusively breastfed (EBF) and partially breastfed (PBF) infants from low-resource Indonesian households.

METHODS

At 2 and 5 months, the breastfeeding status and human milk intake of 212 infants were determined using the deuterium oxide dose-to-mother technique, and intakes were calculated from milk micronutrient concentrations and 3-d weighed food intakes. At 5 months, five infant micronutrient biomarkers, hemoglobin, C-reactive protein, and α-1-acid-glycoprotein were measured. Infant morbidity, weight, and length were measured at 2, 5, and 12 months. Means, medians, or proportions were reported for each group and differences between groups were statistically determined.

RESULTS

Median intakes of iron, thiamin, niacin, and vitamin B-12 were higher in PBF than EBF infants at 5 months (all P values < 0.05), but intakes in all infants were below adequate intakes. At 5 months, anemia was <20% in both groups, although fewer PBF versus EBF infants had vitamin B-12 deficiency (11.5% vs. 28.6%, respectively; P = 0.011). The mean ± SD length-for-age z-scores for EBF versus PBF infants at 2 months were 0.7 ± 0.9 versus -0.5 ± 1.1, respectively  (P = 0.158), declining to -1.4 ± 0.9 versus -1.1 ± 1.2, respectively, at 12 months (P = 0.059). Reported morbidity rates were generally low, with no evidence of a difference between infant groups (all P values > 0.126).

CONCLUSIONS

Irrespective of exclusive or partial breastfeeding status, micronutrient intakes of infants were low, statuses were compromised, and growth faltering during the critical 6 months period of early infancy was present. The findings highlight the importance of improving maternal nutritional statuses and evaluating their impacts on infant outcomes.

Complementary feeding of infants and young children 6 to 23 months of age

Complementary feeding, when foods are introduced to complement a milk-based diet, generally occurs between 6 and 23 months of age. It is a critical period for both physical and cognitive development. During this period, the growth rate of the brain is one of the fastest during the life span and, consequently, the timing, dose, and duration of exposure to specific nutrients can result in both positive and negative effects. Complementary feeding is more than ensuring an adequate intake of nutrients; it also is about avoiding excess intakes of calories, salt, sugars, and unhealthy fats. Meals are cultural and social events where young children observe, imitate, learn about foods to like or dislike, and form lifelong eating habits and practices. Meals are also when a child learns to touch foods and connect food tastes to how foods look and feel. Ideally, complementary feeding is responsive and promotes child autonomy, but it can also be used to manage behavior problems or overly indulge a child, resulting in long-term consequences for nutrition and health. Therefore, in addition to what a child is fed, attention to how a child is fed is also important. In this review, 12 topics relevant for updating global guidance on complementary feeding were identified: age of introduction of complementary foods; continued breastfeeding; responsive feeding; safe preparation and storage of complementary foods; food textures, flavors, and acceptance; energy and meal and snack frequency; fats, protein, and carbohydrates; dietary diversity; milks other than breast milk; fluid needs; unhealthy foods and beverages; and use of vitamin and mineral supplements or supplementary foods.

Perspective: Should Exclusive Breastfeeding Still Be Recommended for 6 Months?

The WHO recommends exclusive breastfeeding of infants for the first 6 mo of life (EBF-6). We reviewed the evidence behind concerns related to this recommendation. The risk of iron deficiency among EBF-6 infants can be significantly reduced if delayed cord clamping is performed in all newborns. At the moment there is no population-level evidence indicating that exclusive breastfeeding for 6 mo compared with <6 mo increases the risk of developing food allergies. Mild to moderate maternal undernutrition may reduce amounts of some nutrients in breast milk but does not directly diminish milk volume. Persistent reports of insufficient milk by women globally are likely to be the result of lack of access to timely lactation counseling and social support rather than primary biological reasons. All newborns should have their growth, hydration status, and development carefully monitored. In instances where formula supplementation is required, it should be done under the guidance of a qualified provider taking into account that early introduction of breast-milk supplements is a risk factor for early termination of exclusive breastfeeding and any breastfeeding. We found no evidence to support changes to the EBF-6 public health recommendation, although variability in inter-infant developmental readiness is recognized. We suggest that infant and young feeding guidelines make clear that complementary foods should be introduced at around 6 mo of age, taking infant developmental readiness into account.

Poor dietary diversity and low adequacy of micronutrient intakes among rural Indonesian lactating women from Sumedang district, West Java

Information on micronutrient adequacy of diets of rural Indonesian lactating women is lacking, despite their high nutrient requirements. This is of concern because deficits in micronutrient intakes may compromise the health of both mothers and infants. This study aimed to assess micronutrient adequacy and dietary diversity (DD) among rural lactating women and explore relationships between micronutrient adequacy, DD, and intakes of energy and food groups consumed. We measured in-home 12-h weighed food records and 12-h recalls over three non-consecutive days from 121 exclusively breastfeeding women at 2-5 months postpartum. Next, we calculated intakes of energy and 11 micronutrients and estimated probability of adequacy (PA) for usual intakes of 11 micronutrients for each women taking into account national fortification of wheat flour with thiamin, riboflavin, folate, zinc, and iron. We assessed DD from nine food groups consumed. Energy and macronutrient balance were within recommended ranges, yet population prevalence of adequacy was less than 50% for niacin, vitamins B6 and C, and less than 60% for calcium, vitamin B12 and vitamin A, all micronutrients not targeted by the national wheat flour fortification program. In contrast, population prevalence of adequacy for the fortified micronutrients was at least 60%, with iron and zinc attaining 79% and 97%, respectively. Overall mean population prevalence of micronutrient adequacy was 57% and mean (±SD) DD score was 4.3±1.2. Mean PAs, a composite measure based on individual PAs over 11 micronutrients, were strongly correlated with energy intakes and with DD scores. In the multivariate models with maternal education and wealth index as covariates, organ meats were the most important determinant of mean PA after controlling for energy intake. In conclusion, despite wheat flour fortification, lactating mothers remained at risk of multiple micronutrient inadequacies. Increasing intakes of animal source foods including organ meats, and fruits and vegetables should be considered.

The transition of breastfeeding children with cleft palate and lip among women

Abstract Objective: To discuss the maternal transition in the breastfeeding process of children with cleft lip and palate, from the perspective of the transition theory. Method: Qualitative research of the case study type. The semi-structured interview was used as a data collection instrument. The results were analyzed from the Transition Theory. Results: The participant presented the transitions: situational, developmental and health-illness due to the change of social roles, the need to care for the child with malformation and the changes in her life due to her child's illness. It was identified, in the participant, the difficulty of exercising maternal breastfeeding care, interfering in its developmental and situational transition. Conclusion and implications for practice: The transitions were ineffective in taking into account the transitions covered. The presence of a nursing professional in the evaluation, follow-up and supplementation of the mother in the suckling of children with cleft lip and palate is essential to achieve the healthy transition.