The main source of vitamin D for Australians is exposure to sunlight. Thus, levels of serum 25-hydroxyvitamin D3, the indicator of vitamin D status, vary according to the season and are lower at the end of winter.
In Australia and New Zealand, the prevalence of vitamin D deficiency varies, but is acknowledged to be much higher than previously thought. One study found marginal deficiency in 23% of women, and another frank deficiency in 80% of dark-skinned and veiled women. The groups at greatest risk of vitamin D deficiency in Australia are dark-skinned and veiled women (particularly in pregnancy), their infants, and older persons living in residential care.
Only a few foods (eg, fish with a high fat content) contain significant amounts of vitamin D. In Australia, margarine and some milk and milk products are currently fortified with vitamin D.
The average estimated dietary intake of vitamin D for men is 2.6–3.0 µg/day and for women is 2.0–2.2 µg/day. The estimated dietary requirement of vitamin D is at least 5.0 µg/day and may be higher for older people.
Adequate intake of vitamin D is unlikely to be achieved through dietary means, particularly in the groups at greatest risk, although vitamin D-fortified foods may assist in maintaining vitamin D status in the general population.
An appropriate health message for vitamin D needs to balance the need for sunshine against the risk of skin cancer.