Human milk oligosaccharide secretion dynamics during breastfeeding and its antimicrobial role: A systematic review

Table 1 Breastfeeding secretion dynamics in the first two years of lactation

Stage of lactation	Time period	Milk volume	Key nutritional components	Key bioactive components	Primary functions	Additional notes
Colostrum	First 3-5 days postpartum	Low (10-40 mL per feed)	High in protein, low in fat and lactose	High IgA, lactoferrin, HMOs, leukocytes, growth factors (e.g., EGF)	Provides passive immunity, protects gut mucosa, supports gut microbiota development, aids intestinal repair	Proteins: Peak concentration, casein: whey ratio approximately 20: 80- HMOs: Highest (approximately 15-20 g/L)- Growth factors: Abundant EGF for gut development- Fats: Minimal but rich in essential fatty acids
Transitional milk	Days 5–14 postpartum	Increasing (approximately 500-750 mL/day)	Protein decreases, fat and lactose increase	Reduced IgA and leukocytes; lactoferrin and lysozyme persist	Supports growing caloric needs, continues immune protection, aids microbiota development	Proteins: Decline begins- Lactose: Increases to support energy needs- HMOs: Decline slightly but remain significant- fats: Gradual increase, influenced by maternal diet
Mature milk	Weeks 3 onward	High (700-900 mL/day)	Stable macronutrients: approximately 0.8%-1% protein, approximately 4%-5% fat, approximately 7% lactose	Balanced levels of HMOs, lactoferrin, lysozyme, and antibodies	Provides complete nutrition, supports immune and brain development, protects against infections	Proteins: Casein: Whey ratio shifts to approximately 50: 50- HMOs: Decline (approximately 5-10 g/L) but bioactive- Immune Factors: IgA, lysozyme, and lactoferrin persist- Fats: Higher variability based on maternal diet
Months 6-12	Late lactation phase	Gradual reduction (approximately 500-800 mL/day)	Similar macronutrient composition as mature milk	Persistent immune factors (IgA, lysozyme, HMOs, lactoferrin)	Complements solid foods, supports immune and microbiota maturation	Fats: Continue to vary, contributing to brain and energy needs- HMOs: Moderate levels (approximately 2-5 g/L)- Lactose: Steady for energy support- Immune Factors: Immune benefits adapted for growing infant
Months 12-24	Toddler phase	Further reduction (approximately 300-500 mL/day)	Macronutrients adapt to reduced dependence on milk	Sustained immune components (IgA, lysozyme, lactoferrin)	Provides immune protection, complements toddler diet, supports growth and immunity	Proteins: Further adapted to complement the solid diet- HMOs: Persist at low levels (< 2 g/L)- Immune factors: Support immune resilience- Fats: Important for energy and essential fatty acids

This table provides a detailed view of the changes in breastfeeding dynamics and their biological significance. EGF: Epidermal growth factor; HMOs: Human milk oligosaccharides; IgA: Immunoglobulin A.