The truth about vitamin D

It’s one of life’s little ironies that we live in a country with abundant sunshine yet every year the rates of vitamin D deficiency in the Australian population continue to soar.

Health experts know the importance of maintaining adequate levels of vitamin D and there is increasing evidence that this is also a contributor to our overall health. While studies are still embryonic, there are signs that low levels of vitamin D is linked to serious illnesses such as heart disease, diabetes and some cancers.

Vitamin D helps our body absorb calcium, and that’s a major factor for maintaining our bone health and muscle mass.

As we get older, being vitamin D deficient is known to be a mitigating factor in increased falls and bone fractures, says Osteoporosis Australia, with more than six million Australians known to have low bone density. Osteoporosis Australia is currently inviting people to visit their website to try the 'Know Your Bones' bone health assessment tool.

Experts say the best way to “top up” on vitamin D is to spend some time outdoors in the sunshine; especially recommended in winter.

Australian Bureau of Statistics figures in 2011 found that by the end of winter, nearly 50 per cent of all Australians in Victoria, Tasmania and the ACT had a vitamin D deficiency, with NSW not far behind with around 40 per cent.

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Professor Mason suggests getting in the sun between 11am and 1pm on a daily basis in winter

It was only the sunnier states of Queensland, Western Australia and the Northern Territory that had far lower percentages – generally less than 20 per cent.

While those percentages may fluctuate from year to year, experts agree that many of us need to rethink our relationship with the sun in the colder months. 

Professor Rebecca Mason, the head of physiology and deputy director of the Bosch Institute at Sydney Medical School at the University of Sydney, who has studied vitamin D for decades, says that exposing parts of our body – arms and legs, for example – to sunlight is by far the preferred way to get vitamin D.

“Energy absorption from sunlight is absolutely critical to make vitamin D in skin and the high energy is only available from the UVB part of sunlight,” says Professor Mason. This means we need to try to get in the sun between 11am and 1pm on a daily basis in winter, she adds.

However, there is a resistance to getting out there among many Australians, who are often worried about sun exposure and skin cancer as well as preferring to stay indoors.

“One of the biggest problems with some older Australians is that they just don’t get outside enough,” says Professor Mason. “Mobility can be an issue, not being well enough and generally not wanting to go out.”

There is a lot of confusing information on the internet about how much sun on your skin you need to maintain healthy vitamin D levels. It depends, in fact, on where you live. In Cairns, for example, you will probably only need about 10 minutes per day, whereas in Melbourne or Hobart, you will need at least 40 minutes. Unless you’re playing sport or doing something physical to keep you warm, this can be extremely difficult when it’s freezing cold outside.

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Sunshine is a great source of vitamin D as food may provide only 10 per cent of your daily requirement

So are there any worthwhile alternatives? Not really, says Professor Mason, though some, like vitamin D supplements, may be “perfectly reasonable” if you have concerns about skin cancer or other medical, practical or cultural reasons why going out in the sunshine is not an option.

“The main problem with supplements,” says Professor Mason, “is that we are becoming increasingly aware that being out in the sun has health benefits that are not necessarily just due to vitamin D.”

While there are some foods that do contain vitamin D – such as fish with the skin left on, eggs, meat, some cereals, and margarine – these will only provide about 10 per cent of your daily requirement at best.

The only way to find out if you are vitamin D deficient is to have a blood test. The best time to go is at the end of winter or early spring.

There are no major physical symptoms if your vitamin D levels have dropped - unless you have very low levels. Then, you may notice general aches and pains, bone tenderness, and a much higher risk of bone fractures if you have a fall.

How much time do you spend outdoors during winter?

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