Adequate levels of vitamin D, also known as 'the sunshine vitamin', are metabolised by the human body from as little as 15 minutes sun exposure during the summer months.
The vitamin plays a role in the absorption of calcium, which is crucial for bone health, and in overall health and development.
However during the winter limited sunlight and absence of ultraviolet light at the right wavelength (290 to 310 nm) in the north of the UK mean that many people - especially those with darker skin or those who cover up most of the body for religious reasons - are susceptible to deficiency.
While vitamin D does also occur naturally in foods like oily fish, eggs and fortified breads and cereals, the warning is that "these may still be inadequate when sunshine hours are limited".
The result is that more children are showing symptoms of deficiency and rickets, the bone disease that stems from vitamin D deficiency, and in ethnic minority groups the incidence could be as high as one in 100 children.
In a bid to help address this, the department says pregnant and breastfeeding women and children under the age of four could benefit from taking a supplement containing 10 micrograms of vitamin D a day.
Vitamin D supplements are now being included under the UK's Healthy Start scheme, which supplies certain nutritious foodstuffs and infant formula to vulnerable sections of the community, such as people on state benefits and pregnant women under the age of 18.
Although this programme only covers a small section of the UK population, the message could well prove a boost to the supplements industry at large, particularly as it follows an updated report on vitamin D status from the Scientific Advisory Committee on Nutrition (SACN) published in 2007.
Non-beneficiaries of Healthy Start can also buy the supplements for a small - but unspecified - cost.
Moreover, the department said: "Other supplements can be bought from most supermarkets and pharmacies".
Dr Colin Michie, a paediatrician at Ealing Hospital in London, explained why vitamin D is so important during pregnancy and early childhood.
"Babies receive vitamin D from their mothers while in the womb, and then from breast milk until they are weaned," he said.
"If a pregnant or breastfeeding woman is lacking in vitamin D, the baby will also have low vitamin D and calcium levels which can lead babies to develop seizures in the first months of life."
In addition to concluding that vitamin D status is of particular concern for pregnant and breastfeeding women, infants, the elderly and black and ethnic minority groups, the 2007 SACN report said there is a need for more national surveys to fully quantify the problem and monitor prevalence of deficiency in the future.
It also said that there is an urgent need to standardise laboratory methodologies for the measurement of plasma vitamin D levels, and identify markers of functional outcome in different age and vulnerable groups, for the interpretation of vitamin D status data.