Vitamin D is needed to absorb calcium from the intestine to support healthy bones. Vitamin D also plays a role in supporting growth and maintenance of the skeleton and regulating calcium levels in the blood.
Sunshine and Vitamin D
For Australians the main source of vitamin D is from exposure to sunlight. Vitamin D is produced when our skin is exposed to ultraviolet B (UVB) light from the sun. Limited sun exposure is needed to produce adequate levels of vitamin D. Exposure times vary based on the season and location within Australia. Skin type and the amount of skin exposed also affects the amount of sun needed for healthy bones.
It is important to balance the need for limited sun exposure for vitamin D, while avoiding the risk of any sun damage. In line with Cancer Council Australians recommendations when the UV Index is 3 or above sun protection is required when outdoors for more than a few minutes.
Recommended sun exposure for vitamin D based on location within Australia.
Vitamin D Levels
Vitamin D levels change throughout the year. Your levels are highest in late summer and lowest at the end of winter. Healthy Bones Australia recommends a vitamin D level of at least 50 nmol/L at the end of winter and during summer higher levels are common in the range of 60-70 nmol/L.
Your doctor will only test your vitamin D level (with a blood test) if you are at risk of vitamin D deficiency. People at risk include:
- Adults mainly indoors due to health or work
- Sun avoiders due to skin protection or medical advice
- Medical conditions which can impact the ability to absorb / process vitamin D
- Elderly, housebound or in residential care
- Naturally dark skinned (darker skin reduces the penetration of UV light)
- Covering body for cultural or religious reasons
- Pregnant or breastfeeding women
Vitamin D Deficiency
In Australia over 30% of adults have a mild, moderate or severe deficiency of vitamin D. Vitamin D deficiency can lead to osteoporosis, result in bone and joint pain, and increase the risk of falls and related fracture in older people
In addition it can impact an unborn child in a vitamin D deficient mother, resulting in rickets (in severe cases) and be linked to other diseases such as some cancers.
Vitamin D Supplements
For people with low vitamin D levels a supplement may be required as advised by your doctor or pharmacist. Low vitamin D levels can be easily corrected but may take several months to improve. Vitamin D supplements are available as tablets, capsules, drops or liquid. Most vitamin D supplements are vitamin ‘D3’ and the standard dose is in International Units (IU). Your doctor will advise you on the appropriate dose required and your pharmacist can provide general advice on vitamin D supplements.
Healthy Bones Australia recommends the following doses of vitamin D as a general guide only:
|Example Circumstance||Recommended Vitamin D Intake|
|People who obtain some sun exposure but not at the recommended level||Adults at least 600IU per day, over 70 years at least 800IU per day|
|Sun avoiders or people at risk of vitamin D deficiency||Higher doses may be required 1,000 IU - 2,000 IU per day|
|Moderate to severe vitamin D deficiency||3,000 – 4,000 IU per day for 6-12 weeks to raise the level of vitamin D quickly, followed by a maintenance dose of 1,000 -2,000 mg per day, as advised by a doctor.|
Vitamin D and Food
Food cannot provide an adequate amount of vitamin D. A limited number of foods contain small amounts of vitamin D such as egg yolks, liver, oily fish (salmon, tuna, mackerel, herring) and select products fortified with vitamin D (eg milk powder, margarine, fresh milk, cereal).