Children's bones keep growing throughout childhood. They grow fastest during toddlerhood and puberty.
Their bones keep getting bigger and stronger until they reach what's known as "peak bone mass". This usually happens between the ages of 18 and 25.
Building strong bones during childhood will provide protection against the fragile bone disease osteoporosis later in life.
You can protect your child's bone health with some simple lifestyle measures.
Your child's bone-friendly diet
Bone-strengthening exercises for children
Eating disorders and bone health
Bones need foods from all the main food groups to stay strong and healthy.
For tips on how to give your child a healthy, balanced diet, see the Eatwell guide.
A couple of nutrients are particularly important for building strong, healthy bones: calcium and vitamin D.
Calcium is particularly vital during puberty when the bones grow quicker than at any other time.
Puberty usually takes place sometime between the ages of 11 to 15 for girls and 12 to 16 for boys.
Research shows that, on average, children and young people in this age group don't get enough calcium.
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 fortified with calcium, including some soya and almond milks.
Vitamin D is important for bones because it helps our bodies to absorb calcium.
Vitamin D is made in our skin when it's exposed to sunlight during the summer months (late March/April to the end of September).
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.
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.
See Food for strong bones.
Your health visitor, pharmacist or doctor can advise you on vitamin D supplements for your child.
Find out more about vitamin D supplements .
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.
To help build healthy bones:
Try not to let your child be sedentary for long periods. Limit the amount of time they spend sitting down watching TV, using the computer or playing video games.
See 10 ways to get active with your kids.
Eating disorders affect people of all ages, both male and female. But girls and women are more likely to be affected, especially during the teenage years.
Teenagers' bones are still growing and strengthening, and eating disorders like anorexia can affect their development.
Low body weight can lower oestrogen levels, which may reduce bone strength. Poor nutrition and reduced muscle strength caused by eating disorders can also lower bone strength.
If your teenage child has anorexia or another eating disorder, it's important to get medical advice early on.
See the National Osteoporosis Society's leaflet, Your children and bone health (PDF, 1.1MB).
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.