Nutritional Content of 100ml Breast Milk
Mature human breast milk contains approximately 1.0-1.3 grams of protein, 7.0-7.2 grams of carbohydrates, and 3.5-4.0 grams of fat per 100ml. 1, 2
Macronutrient Breakdown
Protein Content
- Mature milk contains 0.8-1.0 g/100ml (8-10 g/L) of protein 1, 2
- Protein concentration is markedly higher in colostrum than mature milk and decreases as lactation progresses 3, 2
- Individual variation exists, with reported ranges from 1.1-3.5 g/dL in some studies of mothers with very low birthweight infants 4
Carbohydrate Content
- Mature milk contains 6.9-7.2 g/100ml (60-70 g/L) of carbohydrates, primarily as lactose 1, 2
- Carbohydrate content is lower in colostrum compared to mature milk 2
- An additional 1-2.5 g/100ml consists of oligosaccharides that support infant gut microbiome development 2
Fat Content
- Mature milk contains 3.5-4.0 g/100ml (35-40 g/L) of fat 1, 2
- Fat is the main source of energy in human milk and exhibits the highest variability of all macronutrients 3
- Fat content can vary 2-3 fold between foremilk and hindmilk within a single feeding 3
- Individual variation is substantial, with ranges from 1.0-14.6 g/dL reported in some populations 4
Total Energy Content
- Human milk contains approximately 60-70 kcal/100ml (0.62 kcal/g or 2.6 kJ/g) 3, 2
- Fat provides the majority of calories in breast milk 3
Important Clinical Considerations
Compositional Variability
- Breast milk composition varies significantly based on stage of lactation (colostrum vs. transitional vs. mature milk), time of day, and position within a feeding 3
- Morning samples typically have lower fat content than samples collected later in the day 4
- Maternal diet, race, age, and parity do not greatly affect overall milk composition 2
Water Content
- Breast milk contains approximately 87-88% water, with the remaining 12-13% consisting of solid macronutrients 1
Clinical Pitfall
- When fortifying breast milk for preterm infants, fixed-dose supplementation may not address the substantial natural variability in native breast milk composition, potentially leading to inadequate caloric or macronutrient intake 5
- All pooled breast milk samples in one study required adjustment of at least one macronutrient to reach target fortification goals 5