Most vitamin supplements for children do not contain enough vitamin D, research by Oxford study has found. Parents are advised that all children aged one to four should have a daily supplement, to prevent rickets, a condition that affects bone development in children and which can lead to the growth of soft, weak and deformed limbs.

It is difficult to get enough vitamin D from diet, and the main source is sunshine.

However, the weather in the UK means that there is limited exposure to sunlight from November to March.

Public Health England (PHE) recommends that children aged one to four receive a daily 10 microgram (400IU) vitamin D supplement. Those aged under one should be given a 8.5 to 10 microgram daily vitamin D supplement to ensure they get enough.

But the study found that at least two thirds of products on the market contain insufficient levels.

Researchers from the universities of Oxford and Southampton examined vitamins aimed at children sold by Asda, Morrisons, Ocado, Sainsbury's, Tesco, Boots, Holland and Barrett, Lloyds Pharmacy and Superdrug.

In total, 67 multivitamin products made by 24 different manufacturers were included in the study.

The daily vitamin D dose in the vitamins ranged from zero to 800IU.