Vitamin D deficiency in Australia: how common, who's at risk, and what to do about it

One in four Australian adults are vitamin D deficient — including, surprisingly, more people in our major cities than in the regions. Here's what the data shows, why it happens despite our sunshine, and the steps you can take.

Most Australians grow up with a kind of folk wisdom about vitamin D: we live in a sunny country, so we must have plenty. The reality, when you look at the data, is quite different. The Australian Bureau of Statistics measured vitamin D levels in a nationally representative sample of adults using the gold-standard LC-MS/MS method and found that just under one in four adults — roughly 4 million people — were vitamin D deficient.¹

How common is vitamin D deficiency in Australia?

The most rigorous prevalence data comes from the Australian Bureau of Statistics' National Health Measures Survey. The measurement method was liquid chromatography mass spectrometry (LC-MS/MS) — the same gold-standard method used in hospital reference laboratories.¹

The urban–regional pattern that surprises most people

Australians living in major cities are three times more likely to be vitamin D deficient than those in remote areas:

The driver is straightforward: city life is increasingly indoor life. Office work, car commutes, screen time, sun-avoidance behaviour, and dense urban environments all compress the time most of us spend with skin exposed to UVB.¹

Why deficiency happens despite the Australian sun

• Indoor work and lifestyle. UVB doesn't penetrate window glass meaningfully, so an office workday equals no vitamin D production regardless of how bright the room is.
• Seasonal latitude effects. In the southern half of Australia, the UV Index drops below 3 for much of late autumn and winter. At that level, the skin produces very little vitamin D.
• Skin tone. People with darker skin tones need substantially more UVB exposure to produce the same amount of vitamin D.³
• Body composition. Vitamin D is fat-soluble and gets sequestered in adipose tissue.
• Clothing and sun safety habits. Slip-slop-slap reduces UV damage — and also reduces vitamin D synthesis.
• Diet. Very few foods are naturally rich in vitamin D. Most Australians don't meet requirements through diet alone.

How vitamin D is measured — and what the numbers mean

Vitamin D status is measured by the concentration of 25-hydroxyvitamin D (25(OH)D) in your blood. Australian laboratories typically report in nanomoles per litre (nmol/L), while many home testing services use nanograms per millilitre (ng/mL). The conversion: 1 ng/mL = 2.5 nmol/L.

Who's most at risk

• People with naturally darker skin tones
• People who cover their skin for religious or cultural reasons
• Frail, elderly, and institutionalised people who spend most of their time indoors
• Office workers and shift workers whose daylight hours are spent indoors
• People living south of about 35°S through winter — Melbourne, Hobart, southern NSW
• People with malabsorption conditions like coeliac, Crohn's, or post bariatric surgery
• Exclusively breastfed infants whose mothers are deficient, and pregnant or breastfeeding women themselves — see our Australian guide to vitamin D testing in pregnancy for the clinical detail.
• People with obesity — vitamin D gets sequestered in adipose tissue
• Vegans and strict vegetarians who don't consume vitamin-D-fortified products — our guide for plant-based Australians covers what dietary sources realistically deliver and where supplementation fits in.
• Athletes and serious recreational exercisers, particularly indoor-sport athletes and those training through winter — our guide for Australian athletes covers performance, recovery, and injury-risk evidence.

What does deficiency feel like?

The trickiest part of the picture: symptoms are non-specific. Most mildly to moderately deficient people feel fine, or attribute mild symptoms to other causes. When symptoms appear, they often include persistent low energy or fatigue, muscle aches or weakness, bone pain or tenderness, low mood (particularly through cooler months), and more frequent respiratory infections through winter.⁴

Because these symptoms overlap with many other conditions, you cannot diagnose vitamin D deficiency from symptoms alone — and you can't rule it out from the absence of symptoms either. The only definitive answer is a blood test.

Balancing sun safety and vitamin D

Australia faces a unique public health question: we have the highest skin cancer rates in the world, and we're also at risk of vitamin D deficiency. Cancer Council Australia's position:³

• When the UV Index is 3+, sun protection is recommended. Most people maintain vitamin D through incidental exposure.
• When the UV Index is below 3 (winter in southern AU), spend time outdoors in the middle of the day with some skin uncovered.
• Sunscreen has minimal impact on vitamin D levels in real-world use.
• Overexposure to UV is never recommended, even if you're deficient.

What you can do

1. Sensible incidental sun exposure

A few minutes of incidental sun on bare skin most days — outside peak UV hours in summer — supports adequate vitamin D production for light or medium skin tones. Darker skin tones may need three to six times that exposure.³

2. Dietary sources

Oily fish (salmon, sardines, mackerel, tuna), egg yolks, liver, and UV-exposed mushrooms. Fortified foods contribute too.

3. Supplementation if needed

NHMRC recommends adequate intake of 5–15 µg per day depending on age, when sun exposure is minimal.² Standard Australian supplements are 1,000 IU (25 µg) per capsule.

4. Test, don't guess

Because deficiency symptoms are non-specific and seasonal variation can swing your levels meaningfully, knowing your actual number is the only way to act on the right information.