Is it necessary to give vitamin D supplements to fully breast fed babies?

I always test vitamin D during the pregnancy and if the mother is deficient, then I prescribe supplements. 

If it has been determined that you are vitamin D deficient as a lactating mother, then it would be a good idea to supplement both you and your baby although you should always seek advice from a health professional first so that they can recommend a safe dose.  Vitamin D is a fat soluble vitamin and therefore it is possible to overdose which could be harmful.

The American Academy of Pediatrics recommends that all babies receive routine vitamin D supplementation (400 IU per day) due to decreased sunlight exposure and an increase in rickets. In Australia this is not always the case as some babies do get enough sunlight. Some mothers do cover their baby’s with sunscreen or clothing.

The babies who do need these supplements need them due to a lack of sufficient sunlight. Factors that put your breastfed baby at risk for vitamin D deficiency (rickets) are:

• Baby has very little exposure to sunlight. For example: if you live in a far northern latitude, if you live in an urban area where tall buildings and pollution block sunlight, if baby is always completely covered and kept out of the sun, if baby is always inside during the day, or if you always apply high-SPF sunscreen.
• Both mother and baby have darker skin and thus require more sun exposure to generate an adequate amount of vitamin D. Again, this is a “not enough sunlight” issue – the darker your skin pigmentation, the greater the amount of sun exposure needed. There is not much information available on how much more sunlight is needed if you have medium or darker toned skin.
• Mother is deficient in vitamin D – there is increasing evidence in the last few years indicating that vitamin D deficiency is becoming more common in western countries. The amount of vitamin D in breast milk depends upon mom’s vitamin D status. If baby gets enough sunlight, mom’s deficiency is unlikely to be a problem for baby. However, if baby is not producing enough vitamin D from sunlight exposure, then breast milk will need to meet a larger percentage of baby’s vitamin D needs. If mom has minimal exposure to sunlight (see above examples) and is not consuming enough foods or supplements containing vitamin D, then she may be vitamin D deficient.

The best way to get vitamin D, the way that our bodies were designed to get the vast majority of our vitamin D, is from sun exposure. Depending upon where you live, going outside regularly is often all that is required for you or your baby to generate adequate amounts of vitamin D. (Keep in mind that there is a concern of sunburn and increased risk of skin cancer with too much sun exposure, however.)

The primary source of vitamin D for babies, other than sunlight, is the stores that were laid down in baby’s body prior to birth. Because mom’s vitamin D status during pregnancy directly affects baby’s vitamin D stores at birth and particularly during the first 2-3 months, it is very helpful for pregnant women to make sure they are getting enough vitamin D.

Adding a vitamin D supplement to mom’s diet and/or exposure to ultraviolet light will increase the amount of vitamin D in her breast milk. As long as mom is not vitamin D deficient, her breast milk will have the right amount of vitamin D. However, babies were “designed” to get only part of their vitamin D from breast milk and the remainder from sun exposure – what if baby does not get a minimum amount of sun? A 2004 study [Hollis & Wagner 2004] determined that supplementing the mother with 2000-4000 IU vitamin D per day safely increased mother’s and baby’s vitamin D status: the 2000 IU/d dose resulted in a limited improvement, and “A maternal intake of 4000 IU/d could achieve substantial progress toward improving both maternal and neonatal nutritional vitamin D status.” A Finnish study [Ala-Houhala 1986] showed that supplementing the mother with 50 µg (2000 IU) vitamin D per day was as effective for maintaining baby’s vitamin D levels as supplementing the baby with 10 µg (400 IU) per day.