Vitamin D & Bone Health

Vitamin D is needed to absorb calcium from the intestine to support healthy bones. Vitamin D also plays a role in supporting the 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.

Seasonal Changes

In summer a few minutes mid-morning or mid-afternoon (outside UV Index 3 or above) is generally adequate for vitamin D and in winter longer exposure times are needed. Refer to sunshine map below and check the UV index via the SunSmart app, myuv.com.au or Australian Bureau of Meterology website.

Sunshine Map

Recommended sun exposure for vitamin D based on location within Australia.

Map - 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 CircumstanceRecommended Vitamin D Intake
People who obtain some sun exposure but not at the recommended levelAdults at least 600IU per day, over 70 years at least 800IU per day
Sun avoiders or people at risk of vitamin D deficiencyHigher doses may be required 1,000 IU – 2,000 IU per day
Moderate to severe vitamin D deficiency3,000 – 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 IU 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 (e.g. milk powder, margarine, fresh milk, cereal).

Questions and answers about Vitamin D

What is low vitamin D?

Low vitamin D levels should be avoided by getting some safe sun exposure. 
Low vitamin D levels are considered below 30 (nmol/L) and require attention. 
Very low vitamin D levels or severe Vitamin D deficiency is even lower and will usually be corrected with supplements.  
Vitamin D levels of 50 (nmol/L) are sufficient.  
It is common to have higher vitamin D levels in summer, ranging from 60-70 (nmol/L).
Doctors will only test vitamin D levels in people with risk factors for vitamin D deficiency. 

Low vitamin D causes what?

Low vitamin D levels can cause health issues, for example – low absorption of calcium consumed which can impact bones, issues during pregnancy, links to depression, and in severe cases, rickets.

Which fruit and vegetables have vitamin D?

Fruit and vegetables generally have a low vitamin D level, with only specific animal products or fortified products containing some vitamin D, making it difficult to get adequate vitamin D from your diet. 
Natural food with vitamin D (examples: egg yolks, oily fish – salmon, mackerel, tuna, herring, oysters). Foods fortified with vitamin D (examples: milk powder, orange juice, cereal, margarine).

How do I get vitamin D?

You get adequate vitamin D from safe sun exposure or vitamin D supplements. Only a few limited foods provide vitamin D, but these are generally at low levels making it difficult to obtain adequate vitamin D through diet.