Causes of rickets

Rickets usuallyoccurs because of a lack of vitamin D or calcium, although it can also be caused by a genetic defector another health condition.

Lack of vitamin D and calcium

The most common cause ofrickets is a lack ofvitamin D orcalcium ina child's diet. Both are essential for children todevelop strong and healthy bones.

Sources of vitamin D are:

• sunlight your skin produces vitamin D when it's exposed to the sun, and weget most of our vitamin D this way
• food vitamin D is also found in somefoods, such as oily fish, eggs and fortified breakfast cereals
• dietary supplements

Calcium is commonly found indairy products, such as milk, cheese and yoghurt, and green vegetables, such as broccoli and cabbage.

Over time,a vitamin Dor calcium deficiency will cause rickets in children and soft bones(osteomalacia) in adults.

Seepreventing rickets for more information and advice about ensuring your child gets enough vitamin D and calcium.

Who's at risk?

Any childwho doesn't get enough vitamin D or calcium can develop rickets, but there are certain groups ofchildren who are more at risk.

For example, rickets is more common in children of Asian, African-Caribbean and Middle Eastern origin because their skin is darker and needs more sunlight to get enough vitamin D.

Babies born prematurely are also at risk of developing rickets because they build up stores of vitamin D while they're in the womb. Babies who are exclusively breastfed, especially for longer than six months, may also be at risk of vitamin D deficiency.

This is why theDepartment of Health recommends that:

• pregnant and breastfeeding women should consider taking a daily supplement containing 10 micrograms (mcg) of vitamin D
• babies from birth to one year of age, whether exclusively or partially breastfed, should be given a daily supplement containing 8.5 to 10mcg of vitamin D, to make sure they get enough
• babies fed infant formula do not need a vitamin D supplement until they are receiving less than 500ml (about a pint) of infant formula a day, because infant formula is fortified with vitamin D
• children aged 1 to 4 years old should be given a daily supplement containing 10mcg of vitamin D

For more information, readwho should take vitamin D supplements.

Genetic defect

Rare forms of rickets can also occur in some inherited (genetic) disorders.For example, hypophosphatemic rickets isa genetic disorder where the kidneys and bones deal abnormally with phosphate.

Phosphatebinds to calcium and is what makes bones and teeth hard. This leaves too little phosphate in the blood and bones, leading to weak and soft bones.

Other types of genetic rickets affect certain proteins in the body that are used by vitamin D.

Underlying conditions

Occasionally,ricketsdevelops in children with rare forms of kidney, liver and intestinal conditions.These can affect the absorption of vitamins and minerals.