Young children in Bradford are being given free vitamin D after research showed a rise in the number of cases of the bone disorder rickets in the city.
Rickets weakens the bones in both children and adults
Bradford City Teaching PCT is believed to be the first primary care trust in the country to launch such a scheme.
It decided to act after a study found that between 2000 and 2004, more than 300 children were vitamin D deficient.
It has now released £50,000 so that every child under two in the inner city can be offered the vitamin boost.
Shirley Brierley, a specialist registrar in public health who carried out the research, said: "Paediatricians have been concerned for some time about the number of children they are seeing with vitamin D deficiencies - it is increasing.
"We are still seeing children with rickets and low calcium levels due to a lack of vitamin D.
"We should not be seeing any chidren with it at all."
Regulates calcium levels in the bones
90% comes from sunlight
10% comes from food
Food sources - oily fish, eggs, fortified cereals
Breastfed children may need supplements
Signs of deficiency include bone pain and muscle weakness
Paediatricians found that deficiency rates were higher among children of south Asian families, particularly girls.
Many Muslim women are at higher risk because Islamic dress codes prevent the skin absorbing ultra violet light at high enough levels.
As well as providing free vitamin drops, the PCT is also launching a general awareness campaign including leaflets and a DVD to encourage people of all ages to get enough vitamin D.
Sarah Lockyer, senior health promotion specialist at the PCT, said it was important for whole families to understand the importance of vitamin D.
"The vitamin drops offer short-term help for very young children, who are a priority," she said.
However, vitamin D deficiency does not just affect children.
A PCT spokesman said: "Many adults risk developing bone pain, muscle weakness, osteoporosis or osteomalacia by not eating a balanced diet or getting enough exposure to sunlight.
"Those at risk include people who are south Asian, African or African-Caribbean; have low exposure to sunlight, for example women who observe Hijab or spend little time outside; or have a poor diet.
"But to avoid problems in the future, families need to know the facts about the importance of a balanced diet, including foods containing vitamin D, and why sunlight is good for you.
"If people get the right messages and start making simple changes to their diet and daily routine, such as going for a short walk in the sunshine, it can really make a big difference."