Vitamin D and your Baby’s Immune System
What is vitamin D?
Vitamin D, or the sunshine vitamin, has a role in bone health and more recently it has been associated with helping the immune system, which is especially important as your baby begins to move about more and explore the world around them. Uniquely, it can be created by the skin using the UVB rays from the sun. However, in Ireland, our latitude means that we only get effective sunlight in the summer months, and our unpredictable weather makes this even less reliable as a source. Sunscreen, although it protects you and your baby’s skin, it also prevents the skin’s ability to produce vitamin D from the sunlight, meaning that food sources and supplements are important to maintain adequate levels of vitamin D for your baby. Vitamin D is a powerful nutrient because, despite being called a vitamin, in the body it works as a hormone, During pregnancy babies inherit a small store of vitamin D from their mother. However, from birth it is recommended that breastfed babies receive additional vitamin D.
Food sources of vitamin D are limited and include:
- Oily fish – herring, salmon, sardines and mackerel
- Fortified fat spreads
- Fortified milks
- Fortified breakfast cereals
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Vitamin D and the immune system
Long before vitamin D was associated with the immune system, it had been used to try to reduce the risk of certain illnesses and infections. An example of this is the old wives’ tale of giving cod liver oil, a good source of vitamin D, because it was thought to be good for maintaining health.
The role of your baby’s immune system is to defend their body from foreign, invading organisms, promote protective immunity while not reacting to the body’s own cells. Vitamin D is an important component in the immune system as it is involved in some of the reactions used as a defense to infections.
Vitamin D plays a really important role when it comes to responding to an infection. It has an effect on two immune cells in particular - dendritic cells, which help to generate an adaptive immune system and activating the “killer” T cells in the body which are used to defend against and destroy harmful bacteria. It also supports the more specialised immune response that can target foreign bodies. When it comes to vitamin D and your baby’s diet, it is important to ensure they are getting their daily amount, because infants and children with vitamin D deficiency appear to be more susceptible to viral rather than bacterial infections.
A deficiency in vitamin D has also been associated with some autoimmune and respiratory conditions, so it is important to follow the guidance from the Food Safety Authority of Ireland to ensure that your baby meets the vitamin D requirements.
Guidance on Vitamin D Supplementation for Infants
The latest Food Safety Authority of Ireland (FSAI) guidance on vitamin D supplementation in infants aged 0-12 months is:
Babies, from birth to 1 year of age, who are being breastfed should be given a daily supplement containing 5 micrograms (µg) of vitamin D. This should be provided by a supplement containing vitamin D exclusively.
Babies, from birth to 1 year of age, who are fed infant formula should not be given a daily vitamin D supplement if they are having more than 300ml (about 10 fluid ounces) of infant formula a day. This is because infant formula is already fortified with vitamin D.
Babies, from birth to 1 year of age, who are fed a combination of infant formula and breastmilk should not be given a daily vitamin D supplement if they are having more than 300ml (about 10 fluid ounces) of infant formula a day.
Please note: This recommendation is for healthy term infants. Premature infants or infants under on-going medical care may have different vitamin requirements, please contact your healthcare professional for advice.
Guidance on Vitamin D Supplementation for toddlers
The latest Food Safety Authority of Ireland (FSAI) guidance on vitamin D supplementation in children 1-5years is:
A low-dose vitamin D-only supplement (5 μg) is recommended for all 1–5 year olds. From Halloween to St. Patrick’s Day (i.e. during the extended winter months).
- World Health Organisation ‘Vitamin D supplementation in infants’ (2019) Accessed from: https://www.who.int/elena/titles/vitamind_infants/en/
- Food Safety Authority of Ireland ‘Vitamin D’ (2020) Accessed from: https://www.fsai.ie/faq/vitaminD.html
- Health Service Executive ‘Vitamin D for babies 0 to 12 months’ (2018) Accessed from: https://www2.hse.ie/wellbeing/child-health/vitamin-d-for-babies-0-12-months.html
- Aranow C.‘Vitamin D and the Immune System’ (2011) Accessed from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166406/
- Walker V.P., Modlin R.L. ‘The Vitamin D Connection to Pediatric Infections and Immune Function’ (2010) Accessed from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2925470/
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