IBCLC Practice Exam 2025 – Complete Preparation Guide

In late lactation, the whey to casein ratio in human milk is approximately 50:50. This balance is important because both whey and casein proteins play significant roles in the nutrition and development of the infant. Whey proteins are more easily digestible and contain immunoglobulins and other factors that support the newborn's immune system, while casein provides essential amino acids and contributes to the formation of a gel-like structure in the stomach, which slows digestion and provides sustained nourishment.

The 50:50 ratio reflects a natural adjustment that occurs as lactation progresses, supporting the infant's ongoing growth and developmental needs. In contrast, during early lactation, the whey to casein ratio is typically higher in whey protein, which is beneficial immediately after birth. This transition to a more balanced ratio helps prepare the infant for a varied diet as they begin to consume solid foods later on. Understanding this ratio is crucial for lactation consultants as they work to support breastfeeding mothers and their infants throughout the lactation period.