Kids Health Info

Vitamin D

  • Vitamin D is important for bone and muscle health. Vitamin D helps the body absorb calcium and phosphate from food (mostly from milk and dairy). The main role of vitamin D in the body is to make sure there is enough calcium and phosphate to keep the bones healthy and strong. There is also evidence that low vitamin D is linked to other health problems including: a higher risk of bowel cancer, heart disease, high blood pressure, stroke, problems with immunity (how the body fights infections) and autoimmune diseases (including diabetes).

    Most vitamin D is made in the skin when the skin is exposed to the sun. This is the best way for our bodies to make vitamin D. Only a few foods (some types of fish) naturally contain vitamin D. It is hard to get enough vitamin D from food alone. Margarine, baby formula and some types of milk have added vitamin D, but most people only get about a quarter (or even less) of their vitamin D needs from food.

    How much vitamin D do people need?

    • Infants (less than one year old) need 400 IU a day
    • Children and adolescents need 400-600 IU a day
    • Adults, including pregnant or breastfeeding women need 400-600 IU a day (adults aged over 70 years need 400-800 IU a day)

    Low vitamin D can cause

    Many people with low vitamin D do not have symptoms, but some people with low vitamin D get bone and muscle pain. Very low vitamin D can lead to soft bones, causing rickets in children and osteomalacia in adults. Rickets only occurs when children are growing - if a child has softer bones from low vitamin D, the bones can bend causing 'bow legs' or 'knock knees' as well as other changes. Rickets is more likely in children who also have low dairy intake or in babies that breastfeed for a long time without starting solid foods at the normal age (4-6 months).

    Low vitamin D can cause low calcium - this can cause problems with muscle cramps. Low calcium can cause seizures in young babies - if low calcium (or seizures) are found in a baby, they need to come to hospital urgently.

    Groups at risk of low vitamin D

    • People with very dark skin. The colour in skin (melanin) acts as a natural sunscreen and increases the time people need to make vitamin D
    • People who do not expose their skin to sun. People who stay inside or who wear covering clothing
    • Breastfed babies (with other risk factors). Breast milk is the best type of food for babies, but it does not contain much vitamin D. Babies get their initial store of vitamin D from their mothers; so they are at risk of low vitamin D if their mother has low vitamin D and/or if they have dark skin
    • People with conditions affecting how the body controls vitamin D. Liver disease, kidney disease, problems absorbing food (cystic fibrosis, coeliac disease, inflammatory bowel disease) and some medicines (such as anticonvulsants or isoniazid) can affect vitamin D levels

    Vitamin D testing

    • All people at risk of low vitamin D should have a blood test to check their vitamin D level. The normal level for vitamin D is 50-150nmol/L
    • Babies at risk of low vitamin D (babies who are fully breastfed and have at least one other risk factor) can usually start vitamin D supplements (400 IU daily) from birth without testing. Babies with symptoms of low vitamin D need urgent specialist review

    Vitamin D treatment

    People with low vitamin D (levels below nmol/L) should be treated with vitamin D tablets or mixtures so their levels return to the normal range (over 50 nmol/L)

    Vitamin D tablets or mixtures can be low dose (taken daily) or high dose (taken monthly or less often)

    • High dose vitamin D is becoming more widely available - however it is not used in babies aged less than 3 months or during pregnancy or when breast feeding
    • Please tell your doctor if you are on any vitamin D tablets/medicinces. Too much vitamin D can also cause problems. It is important to know that there are lots of different types of vitamin D tablets and mixtures and some of them are very strong. It is always good to bring your medicine when you see the doctor so they can check what you are taking

    People with low vitamin D also need enough calcium in their diet. Most people should aim to have 2-3 serves of dairy each day (1 serve of dairy is equal to 1 glass of milk, 1 tub of yoghurt or 1 slice of cheese)

    Low vitamin D is a long term problem. Once low vitamin D is treated the aim is to make sure vitamin D levels stay normal. People who are at risk of low vitamin D need to make sure they spend enough time outside (see below) and should have their levels checked every year. They may need lifelong supplements


    For most people, low vitamin D can be prevented by spending time outside.

    Sun exposure and vitamin D

    • Most Australians with light skin get enough vitamin D through the sun during normal daily outside activities. People with light skin are at risk of skin cancer - they should always use sunscreen and recommended sun protection. During summer, adults with light skin only need 6-7 minutes outside in the middle of the morning or middle of the afternoon with their arms and face uncovered to make enough vitamin D. Children probably need a similar length of time, so normal outside play during and after school (or kinder/creche) should be enough to make enough vitamin D
    • Most Australian with dark skin need a longer time in the sun (maybe 3 to 6 times as long as someone with light skin) to make enough vitamin D. The colour in their skin protects them against skin cancer, but they should make sure they do not get sunburnt. They do not usually need to wear sunscreen during the autumn, spring or winter. Hats and sunglasses are still important for this group. During the summer, adults with dark skin need around 30-40 minutes in the middle of the day with their arms and face uncovered to make enough vitamin D. However, during the winter, they may need many hours of sun exposure over the week and most people do not spend this long outside in winter (and they are covered because it is cold) and so people with dark skin in the southern parts of Australia may need extra vitamin D tablets or mixtures during winter

    Babies at risk of low vitamin D (babies who are fully breastfed and have at least one other risk factor) can usually start vitamin D supplements (400 IU daily) from birth to prevent low vitamin D. They should continue this until they are at least one year old.

    For more information

    Factsheet developed by RCH Immigrant Health.  First published December 2009. Updated January 2014.

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This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital, Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.