Table 3.

Summary of existing recommendations

Sources	Ref	Date	General recommendations for use of prophylactic vitamin D in infants
WHO	[5]	2019	“Current evidence suggests that vitamin D supplements may be effective in preventing rickets, particularly for infants and children who may be at higher risk due to limited sun exposure or those with darker skin pigmentation, however further research is needed before specific recommendations can be made.” (Category 2 intervention)a
PrevInfad	[6]	2009	Breastfed infants under one year of age have to receive vitamin D supplement of 400 IU/day, starting from the first days of life, and until the child is fed with one litre per day of formula milk fortified with vitamin D. (Grade B recommendation) All infants under one year of age fed with substitute of human milk with less than one litre per day of formula have to receive vitamin D supplement of 400 IU/day. (Grade B recommendation) Children or adolescents with any risk factorb of vitamin D deficiency and who do not acquire 400 IU/day of vitamin D with one litre of fortified milk or enriched aliments (one portion of cereals and one yolk contains 40 IU of vitamin D each) or adequate solar exposition have to receive vitamin D supplement of 400 IU/day. (Grade B recommendation) For children older than one year or adolescents, daily solar exposition at midday without protection during 10 to 15 min in spring, summer and fall is generally recommended for an adequate production of vitamin D. In winter, vitamin D is not produced above 42° North latitude. (Grade I recommendation) Premature children under one year of corrected age need vitamin D intake of 200 IU/kg/day until a maximum of 400 IU/day. (Grade A recommendation)
CDC	[7]	Updated 2018	“All children need vitamin D beginning shortly after birth. • Children younger than 12 months old need 400 IU of vitamin D each day. • Children 12 to 24 months old need 600 IU of vitamin D each day.” “Breast milk usually does not provide all the vitamin D a baby needs, so breastfed babies will need a supplemental source […].” “32 oz of standard infant formula per day contains 400 IU of vitamin D. If your baby is drinking less than this amount per day, he or she may need a vitamin D supplement […].”
NICE	[9]	2008	“GPs and health visitors should offer children’s Healthy Start vitamin supplements (vitamins A, C and D) to all children aged from 6 months to 4 years in families receiving the Healthy Start benefit.”
Global consensus	[17]	2016	“Vitamin D supplementation for the prevention of rickets and osteomalacia • 400 IU/d (10 μg) is adequate to prevent rickets and is recommended for all infants from birth to 12 months of age, independent of their mode of feeding. (1 ⊕ ⊕⊕)c • Beyond 12 months of age, all children and adults need to meet their nutritional requirement for vitamin D through diet and/or supplementation, which is at least 600 IU/d (15 μg), as recommended by the Institute of Medicine. (1 ⊕ ⊕⊕)c” “Candidates for preventive vitamin D supplementation beyond 12 months of age In the absence of food fortification, vitamin D supplementation should be given to: • Children with a history of symptomatic vitamin D deficiency requiring treatment. (1 ⊕ ⊕⊕)c • Children and adults at high risk of vitamin D deficiency, with factors or conditions that reduce synthesis or intake of vitamin D. (1 ⊕ ⊕⊕)c” “Prevention of nutritional rickets/osteomalacia: identification of risk factors • In addition to an intake of 400 IU/d of vitamin D, complementary foods introduced no later than 26 weeks should include sources rich in calcium. (1 ⊕ ⊕⊕)c • An intake of at least 500 mg/d of elemental calcium must be ensured during childhood and adolescence. (1 ⊕ ⊕⊕)c” “Public health strategies for rickets prevention: • Universally supplement all infants with vitamin D from birth to 12 months of age, independent of their mode of feeding. Beyond 12 months, supplement all groups at risk and pregnant women. Vitamin D supplements should be incorporated into childhood primary health care programs along with other essential micronutrients and immunizations (1 ⊕ ⊕⊕)c, and into antenatal care programs along with other recommended micronutrients. (2 ⊕ ⊕○)c”

Abbreviations:CDC Centers for Disease Control and Prevention, NICE National Institute for Health and Care Excellence, PrevInfad PrevInfad workgroup from the Spanish Association of Primary Care Pediatrics, USPSTF US Preventive Services Task Force, WHO World Health Organization

^aThe eLENA groups the interventions into three categories according to the availability of the evidence as follows. Category 1: Interventions for which there are guidelines that have been recently approved by the WHO Guidelines Review Committee. Category 1 interventions also include those supported by recommendations and other forms of guidance that have been adopted or endorsed by the World Health Assembly. Category 2: Interventions for which systematic review(s) have been conducted but no recent guidelines are yet available that have been approved by the WHO Guidelines Review Committee. Category 3: Interventions for which available evidence is limited and systematic reviews have not yet been conducted

^bSee paragraph below on ‘Risk factors for vitamin D deficiency’

^cRecommendations were graded as 1 for strong recommendation or 2 for weak recommendation; and quality of evidence was assessed as ⊕ ⊕ ⊕ high quality (prospective cohort studies or randomized controlled trials at low risk of bias), ⊕ ⊕ ○ for moderate quality (observational studies or trials with methodological flaws, inconsistent or indirect evidence), and ⊕○○ for low quality (case series or non-systematic clinical observations) [17]