Vitamin D should be added to milk and other food products to halt a rise in cases of rickets in children, say experts at Newcastle University.
The vitamin, produced when skin is exposed to sunlight, is also found in a small number of foods, and deficiency can cause bone deformation. One reason for an increase in cases is thought to be the popularity of indoor activities, such as computer gaming. Professor Simon Pearce said a change in public health policy was needed.
A lack of the vitamin within the traditional UK diet is also thought to be a factor - it can be found in oily fish such as salmon, mackerel, sardines and herring. Writing in the British Medical Journal, Professor Pearce and colleague Dr Tim Cheetham said Vitamin D deficiency had become "disturbingly common" in the UK in recent years.
Dr Cheetham said: "I am dismayed by the increasing numbers of children we are treating with this entirely preventable condition. Fifty years ago, many children would have been given regular doses of cod liver oil, but this practice has all but died out."
Half of all adults in the UK have a deficiency in the winter and spring, with one in six having severe deficiency. The problem is worse in northern regions and could be part of the reason for the health gap between the north and south, according to the university figures.