Vitamin D Deficiency in Babies and Children

Parent feeding a baby with food high in vitamin D

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Vitamin D is a vital nutrient we all need to stay healthy. In babies and children, vitamin D is essential for healthy development including building strong bones and teeth, and normal growth. Not having enough vitamin D (vitamin D deficiency) in childhood can cause long-term health problems and prevent bones from developing properly. 

Why do babies need vitamin D?

Vitamin D helps the body absorb calcium, a mineral needed for the development of healthy bones and teeth

Vitamin D is made by the body in response to sunlight, with a small proportion coming from our diet. This makes it difficult for babies to get enough vitamin D, as sun exposure can damage the skin and is not recommended. Breastmilk alone does not contain enough vitamin D for your baby’s health, even if you are taking a vitamin D supplement.

Do breastfed babies need vitamin D?

Yes. Breastmilk alone does not contain enough vitamin D, and breastfed babies need extra vitamin D. In the UK it is recommended to give a breastfed baby a daily supplement containing 8.5 to 10 micrograms of vitamin D no matter if mother already taking supplements containing vitamin D.

What about bottle-fed babies?

Formula milk is fortified with extra vitamins and nutrients, so if your baby is having over 500ml (around 1 pint) of formula a day, you do not need to give vitamin supplements.

Can a baby have too much vitamin D?

Yes. Too much vitamin D is toxic and can be dangerous for your baby or toddler. A high level of vitamin D is usually caused by giving too much vitamin D supplement so always stick to the recommended amount. If you are not sure how much vitamin D to give your baby, read the patient information leaflet that comes with the medication, or speak to a GP or pharmacist. Taking too much vitamin D causes your body to absorb too much calcium, a condition known as hypercalcaemia which can damage your kidneys. 

Signs of hypercalcaemia in babies include: 

  • Difficulty feeding or not wanting to feed
  • Constipation
  • Polyuria (peeing more than usual)
  • Lethargy (being sleepier than usual)
  • Failure to thrive (not putting on weight) 
  • Irritability
  • Vomiting 
  • Diarrhoea

If you think your baby may have had too much vitamin D, seek immediate medical attention. 

Why do children need vitamin D?

Vitamin D is important to make sure your child grows and develops properly. If your child’s levels of vitamin D are too low this can cause problems with: 

  • Bone development. Vitamin D helps your body absorb calcium, a mineral needed for strong bones and teeth. Lack of calcium can cause a condition called rickets (osteomalacia) where bones become soft and weak, leading to bowlegs and other skeletal deformities. 
  • Immunity. Vitamin D is important for strengthening our immune systems, and low levels of vitamin D may make babies and children more susceptible to disease, meaning they may get ill more often. 
  • Mood. Vitamin D appears to help stabilise our mood, and vitamin D deficiency has been linked to irritability, anxiety and aggression in children and adolescents. 
  • Normal growth. A recent study of children in Ecuador suggested a strong association between stunted growth and low levels of vitamin D.
  • Tooth development. Vitamin D is vital for the development of healthy teeth, and vitamin D deficiency can be a factor in delayed tooth eruption (teeth developing later than normal).

Can children take vitamin D?

Yes. Vitamin D drops are available for babies and children. You may be entitled to free vitamin supplements under the NHS Healthy Start scheme, or you can talk to your health visitor or GP about where to buy them. Always tell your GP or pharmacist about any other medications or supplements your child is taking before starting a vitamin D supplement.

Health advice for vitamin D supplementation in children

In the UK, it is recommended that breastfed babies from birth to 4 years of age receive a daily vitamin D supplement. The recommended doses are: 

  • birth to 1 year: 8.5 to 10 micrograms (mcg) of vitamin D a day. 
  • 1 to 4 years: 10 mcg of vitamin D a day.


If your child has been diagnosed with low levels of vitamin D, your doctor may prescribe a different dose. Always follow your doctor’s instructions carefully and speak to your GP or pharmacist if you have any questions.


Vitamin D deficiency is a common problem and affects many people in the UK including children. As a vital nutrient for your child’s health and development, it is important that vitamin D deficiency is diagnosed and treated early. If you are worried your baby or child may have vitamin D deficiency, make an appointment with your GP or healthcare provider. 

Alternatively, at-home tests for vitamin D deficiency are available from Medicspot. The tests are quick, easy, and reliable with the results available in minutes. We recommend booking an online GP appointment to interpret the results of the test and discuss any necessary treatment.