Sun, vitamin D and bones

The steps

1. Sunlight, carefully

   Sunlight lets your skin make vitamin D, but UV radiation is also the major cause of skin cancer. Cancer Council recommends sun protection when the UV Index is 3 or above.

   Sun exposure and UV

   Source: Cancer Council Australia, Vitamin D

2. Why protection matters

   Even mild sunburn and tanning can contribute to skin cell damage that can lead to melanoma, and Australia has one of the highest rates of skin cancer in the world.

   Skin cancer

   Source: Better Health Channel (Victorian Government), Skin cancer

3. Liver, then kidneys

   The liver turns vitamin D into 25-hydroxyvitamin D, the form a blood test measures, and the kidneys convert that into calcitriol.

   Vitamin D

   Source: Pathology Tests Explained, Vitamin D

4. Building material

   Your body needs vitamin D to absorb calcium. If you do not get enough calcium from food, your body takes the calcium it needs from your bones.

   Calcium

   Sources: NIH Office of Dietary Supplements, Calcium fact sheet for consumers; healthdirect Australia, Calcium

5. Loading the bones

   Walking and strength training can improve bone density, and Australia's guidelines recommend muscle-strengthening activities on at least 2 days a week.

   Strength training

   Sources: healthdirect Australia, Osteoporosis; Australian Government, health.gov.au, Physical activity and exercise guidelines for adults

6. When bones thin

   Osteoporosis makes bones less dense and more fragile, and it has no symptoms until a bone breaks. Women often lose bone mass more quickly after menopause.

   Osteoporosis

   Source: healthdirect Australia, Osteoporosis

Quiz