Preventing Osteoporosis

Vitamin D

Vitamin D is essential for bone health, because it helps:

  • increase the absorption of calcium and phosphorous from the stomach
  • regulate the amount of calcium in the blood
  • strengthen the skeleton.

For Australians, the main source of vitamin D is from exposure to sunlight. Vitamin D3 is formed by the action of sunlight (UV light) on the skin. A deficiency of vitamin D can contribute to osteoporosis because without it, calcium will not be fully absorbed by your body.

Vitamin D is found in small quantities in a few foods (eg fatty fish - salmon, herring, mackerel, liver, eggs, fortified foods). However adequate vitamin D is unlikely to be achieved through diet alone.


Groups and people most at risk of vitamin D deficiency:


  • Older people - particularly those who are house-bound or not able to walk or who live in nursing homes or other institutions (i.e. have limited sunlight exposure).
  • People with gastrointestinal disease, especially with malabsorption eg coeliacs
  • People taking certain medications (eg. antiepileptic agents).
  • People who wear traditional or religious dress that covers most of their head and bodies - giving them limited sunlight exposure.
  • People with dark skin, especially women who cover their bodies ­ getting a limited benefit from sunlight exposure.

The Importance of Sunlight


To get enough sunlight to produce vitamin D, a person needs to expose their hands, face and arms (around 15% of body surface) to sunlight for about 6 - 8 minutes, 4 - 6 times per week (before 10am or after 2pm Standard Time in summer, for moderately fair people).

This would produce around 1000 IU of vitamin D, around 1/3 of a minimal erythemal dose (MED). Note: one MED (minimal erythemal dose) is the amount of sun exposure that produces a faint redness of the skin.

Older people need exposure to sunlight 5-6 times a week. Dark skinned people need longer exposure times of around 15 minutes.

Exposure to sunlight between 10 am and 2 pm in the summer months (11am- 3pm in daylight saving) is not advised or recommended, due to the cancerous effects of sunlight at that time. This outweighs any possible benefits from vitamin D production.


Vitamin D supplements

If you have low vitamin D levels in your blood, your doctor may suggest that you take a vitamin D supplement. Sometimes vitamin D is combined with calcium. Talk to your doctor about the type of supplement they recommend.