Should every child in the UK be given vitamin D supplements?

That’s the latest advice from the Scientific Advisory Committee on Nutrition – but is vitamin D deficiency really that widespread? How do I know if my child is vitamin D deficient? We asked expert rheumatologist Dr Taher Mahmud, who has a specialist interest in bone health, and gastroenterologist Dr Frank Lyons.

How common is vitamin D deficiency in the UK?

As you can imagine, it varies depending on the time of year. According to Public Health England, approximately 30-40% of the UK population is vitamin D deficient in the winter months. Even towards the end of summer, 13% of adolescents remain deficient (compared to 8% of adults).

It’s hard to properly define vitamin D deficiency because it is not exactly a clinical diagnosis. By “deficient” we mean levels that are low enough to cause increased risk of poor musculoskeletal health. So on the whole it’s a significant public health issue.

What are the risks of being vitamin D deficient?

The main risk to children is the impact on bone health. Vitamin D deficiency impairs the absorption of calcium and phosphorus and can thus lead to poor mineralisation of the bones. Adolescence is a critical period for bone health, so without sufficient vitamin D, your child’s bone density can be affected during this time, and they may never reach their full potential of peak bone mass.

Aside from this, vitamin D deficiency can cause muscle weakness at any age.

Finally, there is evidence that vitamin D deficiency in adults is related to osteoporosis, heart disease, multiple sclerosis and mental health issues – but this has yet to be demonstrated in children.

Is my child at risk?

There are a lot of factors that can affect your child’s chances of being vitamin D deficient. Children are at a higher risk of vitamin D deficiency if:

• they rarely go outdoors and expose their skin to the sun
• they wear very concealing clothes
• they use an excessive amount of sunblock
• they are obese
• they have liver or kidney disease
• they have darker skin, especially those o Asian or African ethnic origin

Diet is a factor, but we only tend to get 10% of our vitamin D through our diet. So your child is slightly more at risk if they have a vegetarian or vegan diet, or an exclusion-based diet (e.g. those with a dairy allergy).

The most important factor is the amount of sunlight your child gets.

What about all the advice on keeping children protected from the sun?

The time it takes for us to make sufficient vitamin D from the sun varies from person to person. It can be affected by environmental as well as personal factors. On the whole, however, it doesn’t take long – crucially, less time than the amount of time needed for skin to redden and burn.

Therefore it should be possible to enjoy the sun safely, getting the vitamin D levels required without causing skin damage.

So why are vitamin D supplements recommended?

It’s mainly a precautionary measure, but it reflects the fact that in the UK, while in theory we can get our vitamin D needs from sunlight exposure, in practice it’s difficult. Vitamin D can only be made in the summertime, between April-May and September-October, depending on where you are in the UK. Vitamin D absorption can also be hampered by cloud and also by air pollution.

The Scientific Advisory Committee on Nutrition recommends taking 10 micrograms of vitamin D per day. You can buy vitamin D tablets in pharmacies – it’s not generally necessary to get stronger tablets on prescription, unless in some instances where you child is showing symptoms of deficiency. Finally, it’s best to buy tablets containing only vitamin D, because multivitamin tablets tends to contain far too low a dose of vitamin D to be effective.