Sunshine makes happier children

In a Danish study levels of vitamin D were measured in the women's umbilical cords and the mothers completed a questionnaire on their child's behaviour at two-and-a-half years old.

Children born to mothers with higher levels of the nutrient during pregnancy had less chance of having a child with ADHD, the behavioural disorder.

Professor Niels Bilenberg, of the University of Southern Denmark, said: "The trend was clear. Those mothers who had taken vitamin D and had a vitamin D level in their umbilical blood over 25 nanomoles per litre had children with lower ADHD scores."

Bilenberg said: "Other factors could explain the link, such as the mother's age, smoking, alcohol and obesity."

Co-authors medical students Jens Bull Aaby and Mats Mossin said: "We were surprised the link was so clear as there was no previous awareness that this could be identified at such an early age. It's impossible to say which children will develop ADHD later on, but it will be interesting to follow up these children."

Previous studies have shown that vitamin D plays an important role in the early development of the brain.