The many hours children spend indoors playing computer games or watching television may be to blame for a resurgence of rickets.
Scientists say that rickets is becoming "disturbingly common" among British children. The disease is caused by chronic vitamin D deficiencies, which can be triggered by long periods out of natural sunlight and a poor diet.
Writing in the British Medical Journal, Professor Simon Pearce and Tim Cheetham, of Newcastle University, called for milk and other food products to be supplemented with vitamin D in an attempt to counteract the problem.
Vitamin D is produced naturally when the skin is exposed to sunlight, and is also found in a small number of foods, including oily fish, liver and egg yolks.
Recent studies show that incidence of rickets, a disease previously linked with poverty in Victorian Britain or malnutrition in the developing world, is increasing. More than 20 new cases are discovered every year in Newcastle alone.
Children with rickets do not grow properly and can develop bow legs.
Professor Pearce said: "Kids tend to stay indoors more these days and play on their computers instead of enjoying the fresh air. This means their vitamin D levels are worse than in previous years."
Dr Cheatham, a senior lecturer in paediatric endocrinology, added: "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."
Vitamin D deficiency has also been linked to cardiovascular disease, type 2 diabetes, cancers and the weakening of bones in adults.
Half of all adults in Britain are estimated to suffer vitamin D deficiency in the winter and spring - one in six severely so, with the problem worse in Scotland and the North of England. Asian populations and individuals who cover much of their skin for religious reasons are also at increased risk.
Professor Pearce added: "We believe that a more robust approach to statutory food supplementation with vitamin D, for example in milk, is needed in the UK, as this measure has already been introduced successfully in many other countries in similar parts of the world."
The Food Standards Agency has resisted calls for mandatory supplementation, insisting that "most people should be able to get all the vitamin D they need from their diet and by getting a little sun".
It advises pregnant or breastfeeding women, and people over 60 to take take 10 micrograms (0.01 mg) of vitamin D each day. "Taking 25 micrograms (0.025 mg) or less of vitamin D supplements a day is unlikely to cause any harm," it says.
A study of 520,000 people from ten European countries, including Britain, has suggested that vitamin D supplements could also cut the risk of developing bowel cancer by 40 per cent.
The research, led by Mazda Jenab, of the International Agency for Research on Cancer in France, and published in the BMJ, confirmed the findings of earlier studies, which found that high blood levels of the vitamin were associated with a lower risk of colorectal cancer.
However, the researchers said that it was unclear whether taking vitamin D supplements would provide better protection against developing cancer than the average levels that can be achieved with a balanced diet combined with regular exposure to sunlight.