Your doctor is right. Fortified rice milk can be an acceptable alternative beverage for older children. To understand why rice milk is not recommended for infants, compare its ingredient list and Nutrition Facts label to that of infant formula.
Rice milk contains only water, rice, oil and salt.
It is also low in protein and essential fats. On the other hand, FDA regulations require that infant formulas contain the full nutritional banquet known to be essential for infant health. So, if you need to wean, go with formula. It is the only healthy alternative to breast milk for infants under one year of age. Copyright 1999 Baylor College of Medicine.