Vitamin D deficiency rates cause for concern

Almost one-third of adults over the age of 25 have a Vitamin D deficiency, a new study evaluating the Vitamin D status of Australian adults has found.

The paper is the largest study of its kind, drawing on 11,218 people from the AusDiab Study and includes Australians from Darwin to Hobart. Professor of Medicine (Assistant Dean) and Chair of the NorthWest Academic Centre, Western Section, the University of Melbourne and study author, Professor Peter Ebeling said the findings showed strategies were now needed to improve Vitamin D awareness.

Vitamin D is necessary for optimal health as it helps prevent falls in the elderly and, together with calcium, prevents fractures due to osteoporosis, including hip fractures. Earlier work from this group has also shown that low vitamin D levels are associated with an increased risk of developing type 2 diabetes.

The overall prevalence of vitamin D deficiency (<50 nmol/L) was 31% with women being more commonly affected (39% vs 23% in men, overall). When evaluated by season and latitude, 42% of women and 27% of men in southern Australia during summer/autumn had deficient levels, which increased to 58% and 35% in women and men, respectively, during winter/spring. This indicates that late winter and early spring are the best times to measure vitamin D levels in the blood to detect deficiency.

Those at greatest risk for vitamin D deficiency included women, the elderly, obese, those not meeting the current physical activity guidelines of more than two and a half hours a week, and those of non-European descent.

Importantly, vitamin D deficiency was more common in older and elderly women, the ones most at risk of fractures and falls, both of which are associated with vitamin D deficiency.

"Vitamin D deficiency is recognised as a global public health problem but the population-based prevalence of deficiency and its reach in Australia has never previously been properly examined," said Professor Ebeling.

"The high prevalence of Vitamin D deficiency in our study may also be associated with increasing prevalence of obesity in Australia. Like many developed countries, Australia has experienced an increase in the prevalence of overweight and obesity over the past 20 years. This is likely to be caused by both decreased sun exposure from limited mobility and/or reduced outdoor physical activity."

Professor Ebeling and his co-authors from the University of Melbourne and Baker IDI Heart and Diabetes Institute said it was timely and appropriate to develop national strategies and an awareness campaign for balancing safe sun exposure and adequate vitamin D intake.