Why do Australians have low vitamin D despite the sun?

November 17, 2025 •

4 min read

According to the Australian Bureau of Statistics, one in four Australians over 18 years old suffers from a vitamin D deficiency, a statistic that seems paradoxical given the country's sunny climate. This widespread issue, particularly noticeable during the winter months, is influenced by a complex mix of health guidelines, lifestyle factors, and environmental conditions that collectively explain why so many Australians have low vitamin D.

Quick Summary

This article explores the multiple factors contributing to widespread vitamin D deficiency in Australia, including public health campaigns, geographical location, reduced sun exposure during winter, skin pigmentation, dietary habits, and age-related risks.

Key Points

Sun-Smart Campaigns: Public health campaigns, successful in preventing skin cancer, have inadvertently reduced incidental sun exposure, impacting natural vitamin D production.
Geographical Latitude: Southern Australian states receive less intense UV radiation, especially during winter, leading to higher rates of deficiency in those regions.
High-Risk Groups: Individuals who are housebound, elderly, have darker skin, cover up for cultural reasons, or are obese face a greater risk of vitamin D deficiency.
Dietary Insufficiency: Most natural food sources in Australia contain insufficient vitamin D to meet population needs, despite some mandatory fortification.
Lifestyle Factors: Spending more time indoors, especially in recent years due to lockdowns and sedentary lifestyles, contributes to lower sun exposure.
Balanced Approach: Managing vitamin D levels in Australia requires a careful balance between sun safety and strategic, safe sun exposure, combined with diet and supplementation.

The Sun-Smart Culture: A Double-Edged Sword

Australia's robust and successful 'Slip, Slop, Slap' public health campaign, launched by the Cancer Council, has significantly reduced skin cancer rates since the late 1980s. However, this vital public health message has had an unintended consequence: a reduction in incidental sun exposure, which is the body's primary way of producing vitamin D. The fear of harmful UV radiation has led many to cover up, use high-SPF sunscreen daily, and avoid the sun during peak hours. This has made Australians, ironically, one of the most vitamin D-deficient populations, even in a famously sun-drenched country.

Sun-Safe Practices and Vitamin D Production

The balance between protecting skin from harmful UV rays and gaining enough sun exposure for vitamin D synthesis is delicate. Experts recommend short, unprotected sun exposure, about 10% of the time it would take to get sunburned, on a large area of skin for vitamin D production, depending on skin type and UV levels. Many Australians, however, err on the side of caution, leading to suboptimal vitamin D levels. The 'SunSmart' message, while crucial for skin cancer prevention, requires a nuanced approach regarding vitamin D intake.

Geographical Location and Seasonal Changes

Australia is a vast continent, and latitude plays a significant role in vitamin D production. The UV radiation is less intense in the southern states, like Victoria and Tasmania, especially during winter. The sun's angle is lower, and the days are shorter, making it harder for the body to produce sufficient vitamin D. Winter months consistently show higher rates of deficiency, with nearly half the population in southern parts of the country having insufficient levels.

High-Risk Populations and Their Contributing Factors

Several demographics are at a disproportionately higher risk of low vitamin D levels:

Older Adults: Many elderly Australians, particularly those in aged care facilities or who are housebound, have limited sun exposure.
Individuals with Darker Skin: People with higher melanin pigmentation require more sun exposure to produce the same amount of vitamin D as those with fairer skin. Australia's multicultural population includes many people with darker skin tones, placing them at greater risk.
Covered Skin: Individuals who cover their skin for cultural or religious reasons receive less direct UV exposure.
Indoor Workers: People who spend most of their time indoors, either for work or lifestyle, miss out on critical sun exposure.
Obese Individuals: Obesity has been linked with lower vitamin D levels, possibly due to low physical activity and the sequestration of vitamin D in fat tissue.

Dietary Insufficiency and Fortification

While sunlight is the primary source, dietary intake contributes to vitamin D levels. However, natural food sources rich in vitamin D are limited.

A comparison of vitamin D sources


Source	Pros	Cons
Sunlight	The most efficient and primary source; free.	Risk of skin cancer; effectiveness depends on location, season, and time of day.
Dietary Intake (e.g., fatty fish)	Natural source; provides other nutrients.	Limited number of food sources; often not enough to meet daily requirements.
Fortified Foods (e.g., spreads)	Readily available and convenient; mandatory in some products in Australia.	Variable content; not a primary source; relies on consistent consumption.
Supplements	Accurate, consistent dosage; effective for those with diagnosed deficiency.	Requires a prescription or consultation for high-dose; risk of over-supplementation.

Australia has mandatory fortification of vitamin D in some food products, like margarine, but overall, dietary intake is not sufficient for most to achieve adequate levels. This further explains why Australians have low vitamin D, forcing many to rely on supplements to maintain healthy levels.

Understanding the Vitamin D Paradox

The combination of public health successes in preventing skin cancer and the geographical realities of Australia creates a challenging paradox. The very measures that protect Australians from one major health risk contribute to another. The lack of awareness regarding balanced sun exposure and the limited natural dietary sources mean that the risk of vitamin D deficiency remains high for a large portion of the population. Targeted strategies are needed, including personalized advice on safe sun exposure based on skin type and latitude, and better public awareness about dietary and supplemental sources.

Conclusion

For a country celebrated for its sunny climate, the prevalence of vitamin D deficiency among Australians is a complex issue rooted in a combination of factors. The success of sun-safe campaigns, while vital for combating skin cancer, has inadvertently reduced natural vitamin D synthesis. This, combined with geographic limitations in southern states, seasonal variations, and dietary gaps, places many Australians at risk. Addressing this requires a balanced approach that promotes sensible sun exposure while also educating the public on safe and effective ways to boost their vitamin D levels through diet and, when necessary, supplementation. This ensures that the public can reap the benefits of sun exposure without compromising their skin health.

How to Safely Increase Vitamin D Levels

Strategic Sun Exposure: Engage in short periods of unprotected sun exposure during low-UV periods, particularly outside of peak daylight hours.
Increase Dietary Sources: Incorporate more vitamin D-rich foods such as oily fish (salmon, sardines), eggs, and fortified products into your diet.
Consider Supplements: Consult a doctor about vitamin D supplementation, especially if you fall into a high-risk category or live in the southern parts of Australia.
Monitor Levels: Regular blood tests, especially during winter, can help identify and address any deficiency early on.
Embrace Fortified Foods: Choose products like fortified milk and cereals to help increase your daily intake.

For more detailed information on balanced sun exposure and vitamin D, consult the Australian Cancer Council website.

Frequently Asked Questions

It is surprising because Australia is known as the 'sunburnt country' with a famously sunny climate. However, the paradox exists because public health campaigns promoting sun safety have successfully encouraged Australians to cover up and use sunscreen, limiting the primary way the body produces vitamin D.

No, it does not. Factors such as a person's latitude, the season, time of day, skin tone, use of sunscreen, and time spent indoors significantly influence how much vitamin D is produced, meaning many Australians do not get adequate amounts.

Sun-safe practices, while crucial for preventing skin cancer, reduce the amount of UVB radiation that reaches the skin. Since UVB is necessary for the body to synthesise vitamin D, widespread sun avoidance has led to a population-wide decline in vitamin D levels.

The southern states of Australia, such as Victoria and Tasmania, have higher rates of vitamin D deficiency, particularly during the winter. This is due to less intense UV radiation and shorter daylight hours at these higher latitudes.

For most people, diet alone is insufficient to provide enough vitamin D. Few foods are naturally rich in vitamin D, and while some are fortified, most people do not consume enough of these products to meet their daily needs.

Yes, several groups are at higher risk. These include the elderly, people with darker skin, those who cover their skin for cultural or religious reasons, individuals with obesity, and people who work indoors.

The recommended approach involves a balance of safe, strategic sun exposure, particularly outside peak UV hours. This should be combined with consuming vitamin D-rich and fortified foods and, if necessary, taking supplements under medical supervision.