All children under five are at risk of developing rickets because of their couch potato lifestyles, the government's Chief Medical Officer said.
Professor Dame Sally Davies says children aged six months to five should be given vitamin D supplements - particularly during the winter.
Her advice comes after figures revealed a dramatic increase in the crippling disease in children who aren't exposed to sunlight for long enough, because they stay indoors playing computer games or watching TV.
Dame Sally, the Director General of Research and Development and Chief Scientific Adviser for the Department of Health and NHS, said children should take seven micrograms of the sunshine vitamin every day.
She posted the advice on the Department of Health's website.
