The link between vitamin D and early ADHD symptoms has not been looked at before.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 further follow up these children.”Previous studies have shown that vitamin D plays an important role in the early development of the brain.Mr Aaby added: “We cannot say with certainty that vitamin D protects against early symptoms of ADHD. Our study only indicates that there is a link we cannot explain in any other way.” The trend was clearProf Niels Bilenberg, of the University of Southern Denmark Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. The link between vitamin D and early ADHD symptoms has not been looked at beforeCredit: Aliaksei Lasevich / Alamy Stock Photo Prof 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 (25OHD) in their umbilical blood over 25 nmol/L, had children with lower ADHD scores.“For every 10 nmol/L increase in the vitamin D concentration in umbilical blood, the risk of a being among the 10 per cent highest score on the ADHD symptom scale fell by 11 per cent.”Prof Bilenberg added: “Other factors could explain the link, such as the mother’s age, smoking, alcohol, obesity, and so on.” Pregnant women who sunbathe are less likely to have children who suffer hyperactivity, a study suggests. Vitamin D, the “sunshine” vitamin, also found in foods such as oily fish and egg yolks, seems to protect against the disorder.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.