Australia is one of the sunniest countries in the world. You would think we would have vitamin D sorted. The data tells a different story.
What the numbers actually say
According to the Australian Bureau of Statistics, around a quarter of Australian adults are vitamin D deficient. In winter, that figure climbs to more than a third nationally, and to nearly half the population in Victoria, the ACT, and Tasmania.
The pattern is even more striking when you look at women specifically. Research from a multi-state Australian study found vitamin D insufficiency through winter and spring affected around 67 per cent of women in Tasmania, 37 per cent in the Geelong region, and 40 per cent in southeast Queensland.
That last one is worth sitting with. Even in sunny Queensland, two in every five women are vitamin D insufficient during the cooler months.
Why this is happening
A few reasons that stack up.
First, your body makes vitamin D when bare skin is exposed to ultraviolet B radiation from the sun. UVB is much weaker in winter, particularly south of the Tropic. The further south you live, and the shorter and lower the winter sun, the harder your body has to work to make enough.
Second, modern life keeps us indoors. Desk jobs, screen time, school runs by car, lunches eaten in the office. Most of us spend a fraction of the time outdoors that previous generations did.
Third, women tend to be more sun-protective than men. More sunscreen. More clothing coverage. More time in the shade. All of which are right for skin cancer prevention, and all of which lower vitamin D synthesis.
None of these are personal failings. They are simply the reality of how women in modern Australia live, and the reality means that for most of us, especially through winter, sun alone is not getting the job done.
Why vitamin D matters more than most of us realise
Vitamin D is best known for its role in calcium absorption and bone health, and this alone is reason enough to care. Low vitamin D over years contributes to bone loss, and women are already at higher risk for osteoporosis as oestrogen declines from menopause onward.
But it does much more than that. Vitamin D supports immune function, muscle strength, and there is growing evidence around its role in mood. Low vitamin D has been associated with seasonal low mood, lower energy, and more frequent infections. Emerging research also shows that sun exposure itself, beyond just vitamin D synthesis, triggers anti-inflammatory immune responses and supports cardiovascular health.
What to actually do about it
Talk to your GP about a vitamin D test. It is a simple blood test, and the result tells you something genuinely useful you cannot get any other way.
If you are low, your GP can advise on whether you need a supplement and at what dose. The right amount depends on your starting level, your skin type, where you live, and your other health factors. It is not a one-size answer, and it is not a guess you should be making alone.
Beyond that, brief, sensible sun exposure outside the peak UV hours, and a diet that includes some of the few foods that bring meaningful vitamin D, can help support the work. Oily fish, particularly tinned sardines and salmon, are the standout dietary source. Egg yolks, mushrooms exposed to UV light, and fortified foods contribute smaller amounts.
A note on sun exposure
Vitamin D from sunlight has to be balanced against skin cancer risk, and Australia has the highest rate of skin cancer in the world. The Cancer Council and bone health authorities have a joint position statement on this, and the short version is that sun exposure recommendations vary by season, latitude, skin type, and time of day. For most Australians in winter, particularly those of us in the south, brief incidental exposure to face, hands and arms is helpful. In summer, even short periods can be enough.
The right balance is a personal question for your GP, not a generic rule.
The takeaway: Around a third of Australian adults, and around 40 to 67 per cent of women depending on where they live, are vitamin D insufficient during winter. Modern indoor life and sensible sun protection mean sun alone is not enough for most of us. A GP test is the right starting point.
The science:
- Australian Bureau of Statistics (2013). Australian Health Survey: Biomedical Results for Nutrients, 2011-12. Vitamin D deficiency and insufficiency data across Australian populations.
- van der Mei IAF, Ponsonby AL, Engelsen O, et al. (2007). The high prevalence of vitamin D insufficiency across Australian populations is only partly explained by season and latitude. Environmental Health Perspectives, 115(8), 1132-1139.
- Charoenngam N & Holick MF (2020). Immunologic effects of vitamin D on human health and disease. Nutrients, 12(7), 2097. Vitamin D's role in immune regulation, inflammatory responses, and evidence linking sun exposure to reduced autoimmune disease incidence.
- Cancer Council Australia and Australian and New Zealand Bone and Mineral Society. Joint position statement on vitamin D and sun exposure. Balancing sun exposure benefits with skin cancer risk.