A mother is urging parents to be aware of the importance of making sure their children get enough vitamin D.

Kathryn Ault’s youngest son Toby was diagnosed with vitamin D deficiency after she spotted his legs were not developing properly and he was having problems walking and running.

Ms Ault believed her son, who is almost five, was developing the bone condition rickets, which is on the increase in Britain.

Former model Ms Ault, 28, from Lancing, has three lactose intolerant children.

While supplementing their diets with soya milk and yogurts she was never aware of the connection between calcium and vitamin D.

She said: “It is so important we make sure children do get some exposure to natural vitamin D from the sun or through other supplements.

“I never knew anything about it and I would warn other parents to make sure their child gets the right amount of vitamin D they need.”