Almost one in three Australian adults has inadequate vitamin D status, according to a new position statement published in the 18 June issue of the Medical Journal of Australia.

Professor Caryl Nowson, Chair of Nutrition and Ageing at Deakin University, and coauthors wrote that vitamin D status had increasingly become a "significant public health issue in Australia and New Zealand" since the previous position statement released in 2005.

Improving vitamin D status has been shown to reduce all-cause mortality, and vitamin D plus calcium supplementation reduces the risk of falls and fractures in older people, while vitamin D insufficiency is associated with many diseases such as insulin resistance and some cancers, they wrote.

According to the authors, inadequate vitamin D status occurred in more than 50% of women during winter and spring, and in people residing in southern states.

They said for that people with moderately fair skin, adequate vitamin D levels are likely to be maintained in summer by a walk outside with arms (or equivalent area) exposed for 6-7 minutes mid morning or mid afternoon on most days.

"Short UV radiation exposures (of a few minutes) may be more efficient at producing vitamin D and cause less skin damage", they wrote.

"In winter, the task is more difficult, and in many parts of the country, there is only sufficient UVB radiation to produce vitamin D around noon."

The authors cautioned that vitamin D supplementation may be more appropriate than sun exposure for people at high risk of skin cancer.

Most adults are unlikely to obtain more than 5%-10% of their vitamin D requirement from dietary sources, according to the authors.

They said that, assuming minimal sun exposure, the recommended daily dose of vitamin D from dietary sources and supplementation sufficient to maintain adequate vitamin D levels had increased to 600 IU for most people.