Children's bones keep growing throughout childhood. They grow fastest of all very early in life and when children go through puberty.
The bones keep getting denser until they reach what's known as "peak bone mass". This usually happens between the ages of 18 and 25.
The denser your child's bones are at the time of peak bone mass, the greater their reserves of bone to protect against the fragile bone disease osteoporosis later in life.
"The reserve of bone you establish during childhood and the teenage years is with you through early adulthood," explains Dr Paul Arundel, a consultant in paediatric metabolic bone disease at Sheffield Children's Hospital. "We all start to lose bone mass later in life. If you are starting from a low baseline you are more likely to develop osteoporosis sooner."
The good news is that you can protect your child's bone health with some simple lifestyle measures.
Your child's bone-friendly diet
Building strong bones in childhood requires a range of vitamins and minerals. A healthy, balanced diet will provide this. That means a diet that includes:
- fruit and vegetables – at least five portions every day (but no more than one 150ml glass of fruit juice)
- carbohydrates – such as potatoes, pasta, rice and bread (preferably wholegrain)
- protein – such as meat, fish, eggs, beans, nuts and seeds
- dairy products – such as milk, cheese and yoghurts
There are a couple of nutrients that are particularly important for building strong healthy bones.
Calcium for healthy bones
Our bodies contain about 1kg of calcium. About 99% of this is found in our bones and teeth – it's what makes them strong and hard. Most of this calcium is laid down during childhood and the teenage years.
Calcium is particularly vital during puberty when the bones grow quicker than at any other time. Puberty takes place over a number of years, typically sometime between 11 to 15 for girls and 12 to 16 for boys.
The recommended calcium intake for children and young people aged from 11 to 18 is 800-1,000mg compared with 700mg for adults. But research shows that, on average, children and young people in this age group don't get enough.
"Teens need more calcium because they're growing," says Dr Arundel. "People don't think about bone health in teenagers as much as they do with toddlers, but teenagers are growing a lot more."
Foods that contain lots of calcium include dairy foods such as milk, cheese and yoghurt, but also tinned sardines (with the bones in), green, leafy vegetables (but not spinach), peas, dried figs, nuts, seeds and anything that's fortified with calcium, including some soya milks.
Vitamin D for kids' bone health
Vitamin D is important for bones because it helps our bodies to absorb calcium.
Our main source of vitamin D is sunlight. Vitamin D is made by our skin when it’s exposed to sunlight during the summer months (late March/April to the end of September).
There are only a few foods that are a good source of vitamin D. These include oily fish, eggs and foods that have been fortified with vitamin D, such as fat spreads and some breakfast cereals. Read Food for strong bones.
To ensure they get enough vitamin D, the following groups should take daily vitamin D supplements, to make sure they get enough:
- all babies from birth to one year of age (including breastfed babies and formula fed babies who have less than 500ml a day of infant formula)
- all children aged one to four years old
Everyone over the age of five years is advised to consider taking a daily supplement containing 10 micrograms (mcg) of vitamin D.
But most people aged five years and above will probably get enough vitamin D from sunlight in the summer (late March/early April to the end of September), so you might choose not to take a vitamin D supplement during these months.
It's important never to let your child's skin go red or start to burn. Babies under six months should never go in direct sunlight. Find out how to get vitamin D from sunlight safely.
Find out more about who should take vitamin D supplements and how much to take.
If you receive benefits, you may be eligible for free Healthy Start vitamins, which contain vitamin D. Your health visitor can tell you more, or you can visit the Healthy Start website.
Bone-strengthening exercises for children
Daily physical activity is important for children's health and development, including their bone health.
Try not to let your child be sedentary for long periods. You can do this by reducing the amount of time they spend sitting down, for example, watching TV or playing video games.
Children under five who aren't yet walking should be encouraged to play actively on the floor. Children who can walk on their own should be physically active daily for at least 180 minutes (three hours) spread throughout the day. This should include some bone-strengthening activities, such as climbing and jumping.
Children aged five to 18 need at least 60 minutes (one hour) of physical activity every day, which should include moderate-intensity activity, such as cycling and playground games.
To strengthen muscles and bones, vigorous-intensity activities should be included at least three times a week. This could be swinging on playground equipment, sports such as gymnastics or tennis, or hopping and skipping.
See 10 ways to get active with your kids.
Eating disorders and bone health
Eating disorders affect people of all ages, both male and female. But girls and women are more likely to be affected and anorexia most commonly develops in the teenage years.
The bones are still growing and strengthening at this time and eating disorders like anorexia can affect their development. Low body weight can lower oestrogen levels, which may reduce bone density. Poor nutrition and reduced muscle strength caused by eating disorders can also lower bone density.
If your teenage child has anorexia or another eating disorder, it's important to seek medical advice about their bone health.