In Italy, the currently recommended daily allowance for vitamin D is 10 mcg (400 IU) for infants up to 12 months of age, and 15 µg (600 IU) for children and adolescents [115]. Vitamin D prophylaxis is recommended to all newborns and infants up to 12 months of age, regardless of their being formula or breast-fed [110,116], as also recommended by various others international Scientific Societies [117,118,119,120]. A higher dose is recommended for preterm infants over 1500 gr of weight (600–800 IU/day); for very low birth weight (VLBW) newborns below 1500 gr an intake of 200–400 UI is recommended.