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

Abstract

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 Nonetheless, these resources all suffer major drawbacks, such as being outdated, incomplete profiles, limited sources of data, and uncertain data quality.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.

Influence of breast milk bacteria on breast milk macronutrient levels during lactation

“…In contrast, fat, crude protein, carbohydrate and energy contents were not significantly correlated with total aerobic flora (groups one and three) (Table not shown). These results have been observed in other studies . In this study, fat and energy contents increased with lactation and protein levels decreased throughout breastfeeding, which demonstrated the high variability of the breast milk.…”

Exact determination of optimal nutritional composition for at-risk newborns tolerating enteral intake–breast milk analysis as a routine future standard in neonatal care

“…The mean total content of macronutrients in human milk for populations in the United States and Canada in the period of 1-6 months post partum ranges from 0.79 g/dl to 1.29 g/dl for proteins, from 3.04 g/dl to 4.53 g/dl for lipids, from 6.51 g/dl to 7.56 g/dl for lactose, and from 55.87 kcal/dl to 75.43 kcal/ dl for the energy content (4).…”

“…Human milk is a constantly changing, dynamic, biological fl uid (4). The composition of breast milk varies depending on many factors such as the lactation phase, frequency and routine of breastfeeding, number of previous pregnancies, age of the mother, and diet taken by the mother during the lactation period (3).…”

Neonatal diet impacts liver mitochondrial bioenergetics in piglets fed formula or human milk

“…Recent studies have reported that milk formula-fed (MF) infants present more rapid weight gain during the first weeks of life compared to breastfed infants, and this appears to be associated with weight gain later in life [3][4][5]. The nutrient composition of human milk (HM) in comparison to milk formulas may play a significant role in the observed metabolic outcomes and the reported health differences when comparing these two neonatal diets [6][7][8][9][10][11]. Mitochondrial function and energy homeostasis impinge on all of these systems, but the role of infant diet and programming of cellular bioenergetics remains largely unexplored.…”