Human Milk Composition PDF

Human Milk Composition Infant and Young Child Feeding 3(2-1) Human Nutrition and Dietetics Hajrah Ilyas 1  Human Milk Composition Contains thousands of distinct bioactive molecules that Morbidity and...

Human Milk Composition Infant and Young Child Feeding 3(2-1) Human Nutrition and Dietetics Hajrah Ilyas 1  Human Milk Composition Contains thousands of distinct bioactive molecules that Morbidity and mortality Protect against infection and inflammation Contribute to immune maturation, organ development, and healthy microbial colonization Some of these molecules, e.g., lactoferrin, are being investigated as novel therapeutic agents. 2  Stages of Lactation Colostrum Transitional Mature Milk Milk 3  Colostrum The first fluid produced by mothers after delivery is colostrum Rich in immunologic components such as Secretory IgA  Lactoferrin Leukocytes Developmental factors such as epidermal growth factor 4  Colostrum also contains relatively low concentrations of lactose, indicating its primary functions to be immunologic rather than nutritional Levels of sodium, chloride and magnesium are higher and levels of potassium and calcium are lower in colostrum than later milk. 5  As tight junction closure occurs in the mammary epithelium, the sodium to potassium ratio declines and lactose concentration increases, indicating secretory activation and the production of transitional milk. The timing of secretory activation (lactogenesis stage II) varies among women, but typically occurs over the first few days postpartum 6 Delayed onset of lactogenesis Delayed onset of lactogenesis is defined as onset >72 hours after delivery and appears to occur more often with preterm delivery and maternal obesity, and may be predicted by markers of metabolic health 7  Transitional Milk Transitional milk shares some of the characteristics of colostrum but represents a period of “ramped up” milk production to support the nutritional and developmental needs of the rapidly growing infant, and typically occurs from 5 days to two weeks postpartum 8  Mature Milk By four to six weeks postpartum, human milk is considered fully mature In contrast to the dramatic shift in composition observed in the first month of life, human milk remains relatively similar in composition, although subtle changes in milk composition do occur over the course of lactation 9  Breast Milk Vs. Formula Milk Unlike infant formula, which is standardized within a very narrow range of composition, human milk composition is dynamic, and varies within a feeding, diurnally, over lactation, and between mothers and populations. 10  Compositional Differences Influences on compositional differences of human milk include Maternal factors Environmental factors Milk expression Management of milk (e.g., Its storage and pasteurization) 11 Nutritional Components of Human Milk 12  Sources of Diversity The nutritional components of human milk derive from three sources: Some of the nutrients of milk originate by synthesis in the lactocyte, Some are dietary in origin Some originate from maternal stores Overall, the nutritional quality of human milk is highly conserved, but attention to maternal diet is important for some vitamins and the fatty acid composition of human milk 13  A study in Davis, California examined the association between maternal characteristics and the composition of human milk macronutrients and found that after 4 months postpartum, the macronutrient concentrations of human milk are associated with one or more of the following factors: Maternal body weight for height Return of Menstruation Protein intake Nursing frequency 14  This study also found that mothers who produce higher quantities of milk tend to have lower milk concentrations of fat and protein but higher concentrations of lactose. 15  The most abundant proteins are Casein Α-lactalbumin Lactoferrin Secretory immunoglobulin iga, Lysozyme Serum albumin 16  Non-protein nitrogen-containing compounds comprise ~25% of human milk nitrogen including Urea Uric acid Creatine Creatinine Amino acids Nucleotides 17  Human milk protein concentration is not affected by maternal diet, but Increases with maternal body weight for height Decreases in mothers producing higher amounts of milk 18  Fat Human milk fat is characterized by high contents of palmitic and oleic acids Fat is the most highly variable macronutrient of milk Hind milk, defined as the last milk of a feed, may contain two to three times the concentration of milk fat found in foremilk, defined as the initial milk of a feed The fatty acid profile of human milk varies in relation to maternal diet, particularly, in the long chain polyunsaturated fatty acids 19  Carbohydrates The principal sugar of human milk is the disaccharide lactose The concentration of lactose in human milk is the least variable of the macronutrients But higher concentrations of lactose are found in the milk of mothers producing higher quantities of milk The other significant carbohydrates of human milk are the oligosaccharides, which comprise approximately 1 g/dL in human milk, depending on stage of lactation and maternal genetic factor 20  Micronutrients Many micronutrients vary in human milk depending on maternal diet and body stores including vitamins A, B1, B2, B6, B12, D and iodine The maternal diet is not always optimal, thus, continuing multi-vitamins during lactation is recommended Regardless of maternal diet, Vitamin K is extremely low in human milk The American Academy of Pediatrics recommends an injection of this vitamin to avoid hemorrhagic disease of the newborn 21  Vitamin D also occurs in low quantity in human milk, particularly with low maternal exposure to sunshine While the impact of maternal supplementation with vitamin D on milk composition is under investigation 22