Children’s multivitamins on sale in Tesco, Boots and other major stores are “misleading” parents, experts have warned, after research found the vast majority fail to provide enough vitamin D.

Oxford and Southampton university experts studied more than 67 children’s multivitamin products on the high street and found vitamin D doses varied but only around a third met recommended daily levels.

Vitamin D is an essential nutrient which the body gets from sunlight and diet, and deficiencies in childhood can lead to rickets, a condition that causes bone malformations, weakness and stunted growth.

Producing the vitamin from sunlight is also harder in the winter months and for people with darker skin, and Public Health England recommends children aged one to four take a daily 10-microgram (400IU) supplement.

Many parents may expect that by opting for a multivitamin they’ll be able to meet all their children’s needs, but the latest study shows that belief could be misplaced.

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The researchers selected children’s multivitamin products on sale at Asda, Boots, Holland and Barrett, Lloyds Pharmacy, Morrisons, Ocado, Sainsbury’s, Tesco, and Superdrug.

For children under six months of age, only one multivitamin contained more than 340IU/day vitamin D. Only a third of products for children older than six months, provided the recommended 400IU per day of vitamin D, the experts said.

They also compared 24 vitamin D products that specifically said they were for healthy bones, but even some of these contained as little as 50IU of vitamin D.

It comes after analysis of NHS data showed hospital admissions related to vitamin D deficiency rose by 34 per cent last year, with more than 100,000 cases across England.

“There is a wide range of both multivitamins and vitamin D supplements available for children in the UK, yet most of these do not provide the recommended 400IU/day,” the authors wrote in the journal Archives of Disease in Childhood.

The researchers also looked at specific vitamin D supplements marketed as being for healthy bones.

While they had more vitamin D than the multivitamins, the researchers found only around two-thirds of products provided the full 400IU recommended intake and some had as little as 50IU of Vitamin D.

It comes after analysis of NHS figures showed that there were more than 100,000 hospital admissions in England for vitamin D deficiency last year – a rise of 34 per cent.

A healthy UK diet still provides less than 10 per cent of necessary vitamin D, and as young people spend more time indoors supplementation becomes more important than ever, Dr Benjamin Jacobs, of the Royal College of Paediatrics and Child Health, said.

Dr Jacobs said it was “highly concerning” that so many supplements fall short of recommended levels.

“These products are misleading parents who think they are protecting their children from serious conditions such as rickets, poor growth and muscle weakness,” he added.

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However, health supplement groups said their products are not intended to provide 100 per cent of a child’s nutrients, and lower concentration products allowed young children to be given a smaller dose.

“Food supplements are meant to supplement the diet, not replace the nutrients obtained from foods,” Dr Carrie Ruxton, from HSIS, the industry-funded health and food supplements information service, said.