International Board of Certified Lactation Consultant (IBCLC) Practice Exam

What is the total protein content of mature milk?

1. 0.5%

2. 0.9%

3. 1.2%

4. 1.5%

The correct answer is: 0.9%

The total protein content of mature human milk is approximately 0.9%. This reflects the nutritional needs of infants as they transition from colostrum, which is higher in protein, to mature milk. At around 0.9%, the protein content in mature milk is designed to support the growth and development of the infant without overloading their immature kidneys with excess protein, which can be a concern during early infancy. Mature human milk primarily contains whey proteins, which are highly digestible and provide essential amino acids for infants. The composition is balanced to support abundant growth, brain development, and immune system function. This specific protein level also allows for optimal nutrient absorption and utilization, marking the importance of mature milk in the infant's diet. The other values provided do not accurately represent the typical protein content found in mature milk, as they fall above the expected range for human milk. Therefore, the choice of 0.9% reflects a scientifically supported understanding of the nutritional composition of mature breast milk.