Our sunburnt country needs a dose of the sunshine vitamin
- 2 Jun 2017
New research shows vitamin D deficiency is rife in sunny Australia, prompting dietitians to encourage Aussies to couple safe sun exposure with a healthy 'dose' of nutrient-rich foods containing vitamin D.
The research builds on findings from the Australian Health Survey that found around one in four Australian adults are vitamin D deficient, with the highest rates of deficiency in people living in southern states.
The Curtin University research is being presented at the Dietitians Association of Australia's National Conference in Hobart this week (18-20 May).
Researcher Rachel Cheang said vitamin D deficiency was highest in Victoria (31.1%) and the ACT (28.5%), and was much less common in northern states like Queensland (11.5%) and the Northern Territory (13.1%).
Most people rely on sun exposure to meet their recommended levels of vitamin D, which is made when the sun's UV rays hit the skin. But Ms Cheang said we're getting less sunlight than we used to, largely because we're spending less time outdoors than our ancestors did - and dietary sources of vitamin D can help compensate for this.
"If you struggle to get enough sun exposure during the day, especially over winter, try to eat healthy, whole foods that contain vitamin D. Foods like oily fish (such as salmon, tuna and mackerel), meat, eggs, some dairy foods and mushrooms contain vitamin D and give us a host of other important nutrients," said Ms Cheang.
The 'sunshine vitamin' strengthens bones by helping calcium absorption, and may also be important for immunity against bacteria and viruses. People who get too little vitamin D may develop soft, thin and brittle bones - known as rickets in children and osteomalacia in adults, causing bone pain and muscle weakness.
"We need vitamin D - whether that be from the sun or from food. Get to know the safe levels of sun exposure for where you live and the time of year, and eat healthy foods that are also rich in vitamin D. Vitamin D supplements are also an option, but check with your doctor before taking these," said Ms Cheang.
Vitamin D content of common foods:
* Fish: Oily fish, such as salmon and tuna, is the best source of vitamin D. And new research into white fish (barramundi, basa, hoki and king dory), by Eleanor Dunlop from Curtin University, shows a 100g serve of cooked white fish provides around half (43-60%) of the adequate intake of vitamin D for Australians aged 1-50 years (5mg).
* Eggs: Two large cooked eggs can provide the daily adequate intake of vitamin D for 1-50 year olds (5mg), according to Ms Dunlop's research. Eggs are 'nutrient-dense', providing a host of other important nutrients, like selenium and folate. And our Dietary Guidelines advise that Aussies can enjoy eggs every day.
* Mushrooms: If you add a large handful of mushrooms to your meal, you'll get a significant amount of vitamin D, especially if the mushrooms have been exposed to sunlight during production (look out for 'Vitamin D Mushrooms' in grocery stores). A serve of mushrooms is a serve in the right direction towards getting in enough vegetables - something most Aussie's need to boost. *
* Milk: Some cow's milk has been fortified with vitamin D, so look for these brands if you're at risk of vitamin D deficiency and want an additional way to boost your dietary intake. For example, a 250mL glass can provide around 1.25mg (just over 10% of the daily adequate intake for 1-50 year olds).
"Based on our findings, either two eggs, or one egg and one serve of white fish (depending on species), may allow many Australians to get their vitamin D intake for the day. The vitamin D content of many other Australian foods is unknown, so more work needs to be done to collect this information," said Ms Dunlop.
Ms Cheang said Australian food regulations require vitamin D to be added to margarines and table spreads, and healthier breakfast cereals can now also be fortified with vitamin D.
"People at risk of vitamin D deficiency are those who spend a lot of time indoors or who wear clothes that prevent sunlight reaching the skin, elderly people, those with naturally darker skin, and breastfed babies of mothers who have low levels of vitamin D," said Ms Cheang.
She said overweight and obesity is also linked with poor vitamin D status, with her research showing an 80 per cent greater chance of vitamin D deficiency in people who are obese, compared with those who are a healthy weight.
How much sun is enough for adequate vitamin D?
The Cancer Council recommendsi :
* When UV levels are 3 or above most people need just a few minutes of sun exposure, such as walking from the office to get lunch, to get enough vitamin D.
* When UV levels are below 3 sun protection is not generally required. In some southern areas of the country where UV levels fall below 3 for most of the winter season, you can help maintain your vitamin D by spending short periods outdoors and being physically active.