NHS recommendations are for all youngsters aged six months to five years to be given daily vitamin drops, but parents have to pay for them unless they are part of the free Healthy Start programme.
Evidence suggests take-up of the vitamins is low among poorer families but even children in better-off families may not be not getting enough.
The Nice review comes as Professor Davies published a report on children's health, detailing the need to invest in young people.
It said reducing obesity by one percentage point in children could save the NHS £1 billion a year due to fewer long-term health problems.
More top news
A grieving mother says her faith in humanity is restored after a stolen laptop containing photos of her dying daughter was returned to her.
Rain will ease across central Scotland this morning but it will continue throughout the day across much of Scotland and the north.
An orangutan who has lived in a zoo for the past 20 years, can be granted basic human rights, a court in Argentina has ruled.