Kellie Bilinksi Vitamin D Deficiency Interview

Kellie Bilinksi Vitamin D Deficiency Interview

September marks the start of spring but new research reveals it is also the month when Australians' vitamin D levels are at their lowest ebb.

The University of Sydney study also shows vitamin D deficiency affects more Australians and lasts longer than previously believed.

"Our results suggest that the current guidelines for both vitamin D testing and the use of supplements need to be reviewed," said Professor Steven Boyages from Sydney Medical School.

Professor Boyages and his PhD student Kellie Bilinski recently published their findings in Clinical Endocrinology

"This is the largest ongoing Australian study on vitamin D deficiency ever undertaken," said. Professor Boyages.

"Vitamin D deficiency is implicated in a number of serious diseases including diabetes and cancer so improving our understanding is critical.

"The fact that the government-subsidised cost of testing for deficiency was $96.7 million in 2010 and rising is another reason better knowledge is important."

The study looked at vitamin D levels (by studying the presence of a metabolite) in over 24,000 samples taken from walk-in patients and inpatients in NSW between July 2008 and July 2010. It investigated the effect of age, gender, season, socioeconomic status and remoteness on results.

"Our study indicates that large segments of the Australian population are at risk of deficiency for prolonged periods of the year, particularly during autumn to the end of spring. The prevalence of deficiency was higher and more persistent than previously reported, ranging from 33% in summer to 58% in spring. The seriousness of the deficiency was also greater than in most other Australian reports."

The study found that vitamin D levels peaked in summer, reaching a maximum in January for women and February for men, before declining gradually in late summer and falling sharply in the winter months. They reached their lowest point not in winter, as previously reported, but in early spring.

"Even by December, the first month of summer, levels were still 46% below their peak. Although levels of ultraviolet-B radiation, the body's principal source of vitamin D, would be rising by then, this reflects the time it takes to replenish the body's stores."

Current testing guidelines do not address the need to taken seasonal variation into account.

"Ideally testing would occur in spring when vitamin D levels reach their lowest concentration. If an individual is found to be deficient a subsequent test three months afterwards would see if they have been able to replenish their vitamin D," said Professor Boyages.

"Similarly use of Vitamin D supplements currently fail to address this factor of seasonal variation. A modified approach would see the use of supplements commence, or increase, at the end of summer and be maintained until the end of spring when they would either be stopped or reduced depending on an individual's sunlight exposure."

The study also found that a previously unidentified at risk group is females between 20 and 39 years of age. Further investigation is required to determine the underlying cause for the higher prevalence of vitamin D deficiency in this and other groups.

Steven Boyages is affiliated with Westmead Hospital and eHealth NSW Initiative and Kellie Bilinski with Westmead Breast Cancer Institute.

Interview with Kellie Bilinksi

Kellie Bilinksi , the PhD candidate at Sydney Medical School and co-author of the paper. She is a Senior Clinical and Research Dietician and also works at the Westmead Breast Cancer Institute.

Question: What is vitamin D and why does the body need it?

Kellie Bilinksi: Vitamin D is actually a hormone. It's well known function is for bone health but is also believed to be important to prevention of chronic disease including diabetes and cardiovascular disease as well as MS, depression and cancer.


Question: If we do have a vitamin D deficiency what symptoms might we experience?

Kellie Bilinksi: Can't tell unless chronically deficient for a long period of time in which case muscle soreness (fibromyalgia), osteopaenia (painful bone disease) or fractures may result.


Question: How is a vitamin D deficiency identified?

Kellie Bilinksi: Serum blood test - ordered by GP. We have developed an online calculator to estimate vitamin D deficiency (www.seemyrisk.com


Question: How is a vitamin D deficiency treated?

Kellie Bilinksi: Usually supplements. Generally doctors will recommend 1000-2000 IU per day. For severely deficient people, weekly doses as high as 50000 might be prescribed for several weeks


Question: Can you talk about why you believe women between 20 and 39 are a previously unidentified risk group?

Kellie Bilinksi: We don't know and can only speculate. Some research shows these women protect their skin (ie use sunscreen and stay out of the sun) from the sun more than other groups. They may also be young mothers etc. and tend to be indoors.

Question: What did your latest research find, in regards to vitamin D deficiency?

Kellie Bilinksi: That close to 70% percent of individuals are vitamin D deficient (a level below 50 nmol/L) in spring. People living in major cities were at higher risk and the lowest level occurred in Spring.


Question: Where you surprised by your research results?

Kellie Bilinksi: We were surprised to find that young women had lower vitamin D concentrations than elderly individuals who were traditionally believed to be at the highest risk of deficiency. We also found that more socioeconomically disadvantaged individuals had lower levels.


Question: Why do you believe vitamin D testing and the use of supplements need to be reviewed?

Kellie Bilinksi: Yes. We've shown $100 million was spent on supplements in 2010 and similar figures spent on supplements. There are at present no real guidelines so in fact these should be developed.


Question: If a vitamin D deficiency isn't treated, what other illnesses could develop?

Kellie Bilinksi: Research suggest numerous diseases are related to vit D deficiency (see above).


Question: How can we prevent vitamin D deficiency?

Kellie Bilinksi: Sensible sun exposure (see attached MJA article with table) - generally about 30 minutes early or late in the day or 1000-2000 IU supplementation a day.

I've recently written a fact sheet with a little more detail, you can download it at: www.bci.org.au/about-breast-cancer/fact-sheets/522-vitamin-d-and-breast-cancer.html