Breast milk is universally recommended as the preferred source of infant nutrition, in part because of its superior nutrient and immunologic properties. Successful breast feeding requires nursing on demand, prevention of sore nipples and convenient access to medical advice. For mothers relying on bottle feeding, cow's-milk-based formula is the preferred choice. Because soy-based formulas are lactose-free, they may be tolerated by infants who are allergic to cow's-milk protein. Protein hydrolysate formulas should be used only in infants who cannot tolerate cow's-milk-based or soy-based formulas. Low-Iron formulas and whole cow's milk should not be used during the first year. Breast-fed infants rarely require vitamin supplementation. Fluoride supplementation is no longer recommended for infants less than six months of age.