Vitamin D: what you need to know

Why children need vitamin D

Children need vitamin D for bone growth and development. Vitamin D helps us absorb calcium.

Serious vitamin D deficiency can cause rickets. Vitamin D deficiency has also been linked to osteoporosis, some cancers, heart disease and diabetes.

Babies still developing in the uterus also need vitamin D. If women don’t get enough vitamin D during pregnancy, their children might develop neonatal hypocalcaemia (not enough calcium in the blood) or rickets later in childhood.

How children can get vitamin D

Sunlight
When sun – specifically UVB radiation – shines on our skin, our bodies make vitamin D. We get about 80% of our vitamin D this way. The Cancer Council recommends the following:

• In summer, fair-skinned people can get enough vitamin D from just a few minutes of sun on hands, arms and face every day.
• In winter in Victoria and South Australia, 2-3 hours of sun a week will provide enough vitamin D.
• In winter in Tasmania, more than 2-3 hours of sun a week might be needed (according to recent research).
• In winter elsewhere in Australia, a few minutes a day will provide enough vitamin D.
• Dark-skinned people will need more sun than fair-skinned people. To find out how much sun you need, speak with your doctor.

Note: recommendations aside, there is no conclusive Australian or New Zealand data on how much UVB exposure is needed for children to maintain good levels of vitamin D.

Diet
Most children won’t get enough vitamin D from food alone. Vitamin D-rich foods can supplement the vitamin D your child gets from sunshine.

Foods naturally containing vitamin D include fatty fish (North Sea salmon, herring, mackerel and sardines) and egg yolks.

Some foods don’t naturally contain vitamin D, but have vitamin D added to them. These include margarine and some milk and dairy products. All infant formula contains vitamin D.

You can also take vitamin D supplements.

Vitamin D deficiency

Children might be at risk of vitamin D deficiency if they:

• need to keep all their skin covered (for example, for cultural reasons)
• have an illness that keeps them indoors
• use sunscreen in winter in one of the southern states (those living in a hotter state such as Queensland or the Northern Territory still need sunscreen in winter)
• have a physical or intellectual disability. A Melbourne study found that vitamin D deficiency was high among children with physical and intellectual disabilities. This might be because these children spend more time indoors. It might also be that they have a condition that reduces absorption of vitamin D (such as coeliac disease or cystic fibrosis)
• have darker skin. In these children, more sunlight is needed to produce the same levels of vitamin D that fair-skinned people produce. People with dark skin who also wear a veil have quite a high risk of vitamin D deficiency
• have been breastfed for a long time, are dark skinned and have a mother whose vitamin D is low.

Signs of vitamin D deficiency include rickets (bone deformities), delayed motor development, muscle weakness, aches and pains, and fractures.

Treating vitamin D deficiency

Ask your GP to do a blood test if you’re worried your child might not be getting enough vitamin D, or if you’re pregnant and think you have low vitamin D. A blood test is the best way to check your levels.

If your child has dark skin and doesn’t get enough sun, or if your child can’t go in the sun because of cultural dress requirements or because of a skin condition, talk to your doctor about taking supplements.

For mild deficiencies, make sure that your child gets enough sun. You can also discuss the use of a vitamin D supplement with your GP.

If you or your child has a severe deficiency, your doctor will put you on a course, or one large dose, of vitamin D.

Vitamin D, pregnancy and breastfeeding

A baby’s vitamin D stores increase during pregnancy and go down after birth until the baby starts getting vitamin D from sunlight along with diet. If a pregnant woman has low levels of vitamin D, she might not have passed on enough vitamin D to her baby.

Breastmilk has many benefits, but it’s generally not a rich source of vitamin D. If a mum has low vitamin D while breastfeeding, it can be hard for her baby to get enough of the vitamin. It’s even trickier if the breastfeeding mum lives further south in Australia and it’s winter. There’s a bigger risk of low vitamin D levels for mum and baby in these circumstances. This is because there is less sunlight in winter, and the colder weather might mean people spend more time inside and don’t get enough sunlight.

If you have any concerns about whether your baby is getting enough vitamin D, you can talk with your GP about using a vitamin D supplement. A daily supplement of 400 IU is often recommended for mothers of breastfed babies at risk of vitamin D deficiency. It’s still OK for you to breastfeed your baby when taking a supplement.

Infant formula has higher levels of vitamin D, so formula-fed babies don’t usually need a supplement.

Most cases of rickets in Australia are in dark-skinned children. This is because dark-skinned women – particularly those who wear veils – have been found to have a high risk of vitamin D deficiency and don’t pass on adequate amounts of vitamin D to their children.

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