Final answer:
Cow's milk should not be given to toddlers under age 2 because of its high protein and mineral content, which are difficult for an infant's digestive system. Instead, whole milk, transitional milk, and mature breast milk are recommended in stages, as they provide the proper nutritional balance.
Step-by-step explanation:
The type of milk that should NOT be given to toddlers until at least age 2 is cow's milk. According to guidelines, cow's milk is inappropriate for infants due to its high protein and mineral content, which can be challenging for an infant's immature digestive system. Cow's milk has more protein and minerals than breast milk and lacks the adequate amount of fat and lactose required for an infant's diet. Moreover, the proteins found in cow's milk are difficult for infants to digest. In contrast, breastmilk or infant formula provides the right balance of nutrients. It's important to note that while toddlers need fat for brain development, most health experts recommend whole milk for children over age 1 and under age 2 to ensure they get enough fat for brain development. Transitional milk, which comes in after colostrum and before mature milk, contains intermediate levels of nutrients between colostrum and mature milk. Mature breast milk then changes from foremilk, which is watery and protein-rich, to hindmilk, which is higher in fat.