Vitamin D vs sun exposure

We know too much time in the sun can cause skin cancer, but not enough can lead to low levels of  vitamin D. So how do we balance our time in the sun to stay healthy?

Mixed messages around sun exposure and vitamin D levels has caused confusion for many Aussies.

A Cancer Council survey found 15 per cent of us changed our habits over summer to take in more vitamin D, but most of us (77 per cent) aren’t actually deficient in vitamin D.
Now new national guidelines have been developed to help us ensure we’re getting enough vitamin D, without the risk of harmful UV exposure from the sun.

How much time do we need in the sun?

According to the national guidelines, during summer most Aussies get enough vitamin D through incidental outdoor activities.

Chair of Cancer Council Australia’s Public Health Committee, Craig Sinclair says a few minutes a day outside mid-morning or mid-afternoon is usually enough for most people.

“However, if you are going outside for more than a few minutes and the UV Index is 3 or above, you need to protect yourself - slip, slop, slap, seek shade and slide on sunnies,” says Sinclair.

If the UV index is below 3, sun protection usually isn’t required, unless you work outdoors in the sun.

Professor Rebecca Mason, from the Australian and New Zealand Bone and Mineral Society says during winter many southern parts of Australia have a UV index that is below 3 for most of the season..

“In fact, in those areas (during winter) it is recommended that you spend some time outdoors, preferably being physically active, in the middle of the day,” says Mason. “Getting physically active, by going for a brisk walk during your lunchtime or doing some gardening outdoors, will also help maintain your vitamin D levels.” 

Why is vitamin D important?

Our bodies make vitamin D in our skin  using the energy from the UVB rays in sunlight. Vitamin D is also found naturally in small amounts in a few foods, including fish and eggs, and is sometimes added to dairy products such as milk. 
Our bodies need vitamin D to help us absorb calcium  for healthy bones, teeth and muscles.

If we don’t get enough vitamin D, it can lead to bone and muscle pain and increase the risk of bone and muscle (musculoskeletal) conditions, like rickets (or soft, weak bones) in children and osteopenia (weak, fragile bones) in older adults.
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Does prolonged sun exposure boost vitamin D stores?

According to Associate Professor Peter Foley, from the Australasian College of Dermatologists, it’s a misconception.

“Prolonged sun exposure does not cause vitamin D levels to continue to increase, but it certainly does increase the risk of skin cancer,” Associate Professor Foley says.

“Around two in three Australians will be diagnosed with skin cancer in their lifetime and around 2,000 Australians die each year as a result, so protection against excessive UV exposure remains vital, even for those with vitamin D deficiency.” 

How long do your vitamin D stores last?

Professor Peter Ebeling AO, from Osteoporosis Australia and the Endocrine Society of Australia, says if you get enough  vitamin D in summer, your body can rely on a vitamin D store from one to two months in winter.

“For most of the population, any reduction in vitamin D levels experienced in winter can be corrected at other times of the year when UV levels are higher,” says Professor Ebeling.

Who is at risk of low a vitamin D deficiency?

  • Those with naturally very dark skin
  • People who cover up outdoors for religious or cultural reasons
  • People who are obese 
  • Older people who are housebound or living in care homes 
  • Babies whose mother is deficient in vitamin D
  • People who have had skin cancer or have an increased risk of skin cancer
  • Those who are housebound or spend a long time indoors
 Those who are at risk of a vitamin D deficiency should speak to their doctor about whether a supplement is necessary.
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