International Board of Certified Lactation Consultant (IBCLC) Practice Exam

Which of the following best describes the component that supplies the main energy source in human milk?

1. Fat

2. Protein

3. Lactose

4. Vitamins

The correct answer is: Lactose

The correct answer is lactose, as it is the primary carbohydrate found in human milk and serves as a significant source of energy for infants. Lactose provides about 40% of the total calories in human milk, making it a crucial component for infants' growth and energy needs. It not only fuels the infant's metabolism but also aids in the absorption of essential minerals such as calcium and magnesium. Fat does indeed contribute to the caloric content of human milk, providing a higher percentage of total energy compared to lactose. However, lactose is specifically recognized as the primary carbohydrate that directly supports energy needs in the context of infant nutrition. While protein is essential for growth and development, it does not serve as the main energy source. Proteins are more focused on building and repairing tissues, and though they provide energy, they are secondary to carbohydrates like lactose when it comes to energy sourcing. Vitamins are important for various metabolic functions and overall health, but they do not supply energy directly. Instead, they function as co-factors in many biochemical processes, supporting metabolism rather than contributing directly to the caloric intake of an infant. Thus, lactose stands out as the main energy source in human milk, supporting the unique nutritional requirements of breastfeeding infants.