Breast Milk Composition: What’s in Human Milk?

breast milk and donor milk feeding for premature infants

Breast milk is the gold standard for infant feeding due to its incredible composition of macronutrients, bioactive compounds, and interactive elements.(1) The World Health Organization (WHO) considers breastfeeding an unequaled way of providing ideal food to infants because of the growth-factors and anti-infective components in breast milk.

Nowhere else are the benefits of breast milk more noticeable than the neonatal intensive care unit (NICU). Immunocompromised infants are at considerable risk from bacteria, infection, necrotizing enterocolitis (NEC) and sepsis due to their immature immune system and organs. NICU clinicians take every opportunity to prevent such detrimental impacts on their patients. Larger, healthier infants may be able to defend against infectious diseases, whereas premature infants and at-risk infants are likely not be able to fight against pathogenic invasion.

Part of a NICU frontline defense for their patients is the use of breast milk feeding. Mothers are encouraged to breastfeed if their infant has the suck/swallow reflex capabilities, or to pump breastmilk if their baby cannot breastfeed directly. And when mother’s own milk (MOM) is unavailable, clinicians turn to donor human milk, which enables the benefits of an exclusive human milk diet. The American Academy of Pediatrics (AAP) recommends donor human milk ahead of artificial milk, especially for premature infants. This recommendation is based on research showing human milk’s impact on the reduction of NEC, sepsis, and mortality.

Research has documented many more benefits of human milk to infant health beyond those three. The bottom line: It really is the best nutrition for babies. But what are the wondrous factors in human milk that make it so special? Here are a few:

Human milk macronutrients(2)

  • Proteins (8 g/L) (Casein, α-lactalbumin, albumin)

  • HMOs (5-15 g/L)(3)

  • Lipids (40 g/L) and LCPUFAs (DHA and ARA, essential for brain development)

  • Lactose (70 g/L)

Macronutrients provide the needed nutrition for energy and to maintain structure and systems of the body.


  • Vitamins (Vitamin A, B1, B2, & D)

  • Minerals (zinc, iron, copper, iodine)

Bioactive Compounds(4)

  • Proteins:

- Lactoferrin, secretory IgA, IgM, IgG, lysozyme

- Hormones (leptin, ghrelin, adiponectin, insulin)(5)

- Cytokines (IL-10, TGF-beta, IFN-y, IL-7)

- Growth factors (EGF, HB-EGF, VEGF, IGF-1)

  • Non-protein nitrogen-containing compounds: Urea, uric acid, creatine, creatinine, amino acids, and nucleotides

  • HMOs: Prebiotic, stimulating beneficial colonization and reducing pathogenic colonization; reduce inflammation.(6)

Interactive Elements

  • Gut development: Epidermal growth factors (EGF) and insulin-like growth factor-1 (IGF)

  • Antimicrobial compounds: antimicrobial peptides, and fatty acids

  • Anti-infective components: immunoglobulins

Human Milk is best for babies

The list above could go on for miles. Each aspect of human milk is a carefully crafted feat in natural nutrition engineering, made to improve feeding tolerance, resistance to pathogens, and overall physical development.

All infants can benefit from exclusive human milk feeding. Those most at risk and/or premature are also most in need of exclusive human milk feeding health impacts. And thanks to modern science, mother’s own milk and a reliable donor milk solution can together provide the protection they need.

The Medolac Benefit nutrition portfolio is the only human milk-based nutrition that meets recommendations for commercially sterile replacement feeding in the NICU. Learn more about this shelf stable donor milk resource NICUs rely on to achieve exclusive human milk feeding in their hospital.


1. Garwolińska, D. et al (2018). Chemistry of Human Breast Milk—A Comprehensive Review of the Composition and Role of Milk Metabolites in Child Development. J. Agric. Food Chem. 2018, 66, 45, 11881–11896

2. Donovan SM, Comstock SS. Human milk oligosaccharides influence neonatal mucosal and systemic immunity. Annals of Nutrition and Metabolism. 2016;69(Suppl. 2):41-51

3. Gridneva, Z. et al (2019). Carbohydrates in Human Milk and Body Composition of Term Infants during the First 12 Months of Lactation. Nutrients. 2019 Jul; 11(7): 1472

4. Ballard, O. et al (2013). Human Milk Composition: Nutrients and Bioactive Factors. Pediatr Clin North Am. 2013 Feb; 60(1): 49–74. doi: 10.1016/j.pcl.2012.10.002

5. Mazzocchi, A. et al (2019). Hormones in Breast Milk and Effect on Infants’ Growth: A Systematic Review. Nutrients. 2019 Aug; 11(8): 1845

6. Ballard O, Morrow AL. Human milk composition: nutrients and bioactive factors. Pediatric Clinics. 2013 Feb 1;60(1):49-74