Babies who continue to breastfeed beyond their first birthday must receive vitamin D supplements, a new study found.

The relationship between the amount of vitamin D levels and the duration of babies being breastfed has not yet been fully established. What is known is that the World Health Organization recommends breastfeeding up to 2 years of age, as desired by both the child and the mother.

There has also been an increase in the rates of breastfeeding among babies aged 1 year and above, even if they were receiving solid food already.

Breast Milk: Not A Very Good Source of Vitamin D

Although breast milk is said to contain an array of beneficial nutrients that babies need to grow, it does not provide sufficient amounts of vitamin D.

For this, study author Jonathon Maguire says vitamin D supplements are essential for babies, even if their diet is being supplemented by other food sources aside from breast milk.

Children Up North

The study may be far more important in children living up north, particularly those in Canada where Maguire is based. This is because such places lack exposure to the sun's ultraviolet rays, which is a known source of vitamin D.

Testing Theories

To determine the association between vitamin D levels and total breastfeeding duration, the researchers followed a number of children from birth. The study involved 2,500 babies aged 1 to 5 years old, all of whom were a part of a program that aims to prevent typical childhood nutrition problems and subsequently lessen health impacts later in life.

The results of the research show that after the age of 1, breastfed babies increase their chances of being vitamin D-deficient by 6 percent every month. This means that by the age of 2 and 3, the chance of vitamin D deficiency will rise by 16 percent and 29 percent respectively.

Despite the results, it is not high time to fret as this is when supplements may come in handy.

"Vitamin D supplementation may mitigate this risk," the authors write.

The Canadian Paediatric Society and the American Academy of Pediatrics recommend giving breastfed babies with a daily dose of 400 International Units of vitamin D during the first year of life.

Deficient Vitamin D Risks

There are numerous conditions associated with lack of vitamin D. Particularly, breastfeeding until the first year of life without vitamin D supplementation is said to cause rickets, which results in weak and soft bones.

The study was published in the American Journal of Public Health on Thursday.