Vitamin D in winter

Vitamin D helps the body to absorb calcium, which is needed to build and maintain healthy bones and keep our muscles strong. Vitamin D is made by the body when our bare skin is exposed to ultraviolet (UV) radiation from sunlight. Most people can get adequate vitamin D naturally this way.

People with very low levels of vitamin D are at risk of having bones that are more fragile and prone to breaking. Health experts generally agree that a vitamin D level of 50 nanomoles per litre (nmol/L) or above is adequate for healthy bones.

For people with fair skin, 5–10 minutes in the sun on most days is enough to obtain adequate vitamin D during summer. The good news is you don't necessarily have to make a special trip outdoors during this time of the year – incidental exposure while travelling to and from work or walking outside to buy lunch may be sufficient. However, longer times (a few hours) outdoors are needed over winter in the southern Australian States.

For those with darker skin it can be more difficult to obtain adequate vitamin D from the sun – about 3–6 times more sun exposure is needed.

Small amounts of vitamin D can also be obtained from food such as oily fish and eggs, but these should not be relied on to contribute all of a person's required daily intake.

Certain people are at risk of vitamin D deficiency, including those who:

• are housebound, particularly people aged over 65 years, or in aged care facilities
  
• have naturally dark skin
  
• wear clothing that covers most of their body.

If you are at risk of vitamin D deficiency, a vitamin D test may be beneficial in helping to determine if lifestyle changes and/or supplements are needed to achieve adequate vitamin D levels.

However, if you do not have risk factors for vitamin D deficiency, a vitamin D test is not usually recommended.