5.3. Recommended Daily Allowance and Supplementation
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.
Vitamin D supplementation is also recommended for children and adolescents with risk factors (obesity, reduced sunlight exposure, intestinal malabsorption, chronic hepatic or kidney disease, chronic therapies such as anticonvulsants, ketoconazole, etc.), at the dose of 600 IU/die up to 1000 IU/die in the presence of multiple risk factors [110]. Other societies recommend systematical supplementation of vitamin D during winter months [121,122,123]. In Italy, despite a high prevalence of hypovitaminosis D, there is currently no indication to conduct routine testing in healthy children and adolescents without known risk factors, nor to routinely supplement vitamin D. In case of detection of vitamin D insufficiency (<20 ng/mL), it is recommended to administer a higher dose of vitamin D (2000 IU/day for 6–8 weeks).