Vitamin D deficiency

Am I deficient in vitamin D?

For some people, symptoms of bone pain and muscle weakness can occur as a result of vitamin D deficiency. For others, there may be no obvious signs and symptoms.1 Importantly, bone pain and muscle weakness can occur as a result of other health concerns, not just a shortage of vitamin D. To avoid confusion and assumptions, a simple blood test will determine your body’s level of vitamin D. This is easily arranged through a visit to your GP.

Vitamin D Status

Blood Serum level

Target vitamin D level

70-80 nmol/L3

Mild vitamin D deficiency

25–50 nmol/L

Moderate vitamin D deficiency

12.5–25 nmol/L

Severe vitamin D deficiency

less than 12.5 nmol/L

Table 1. Vitamin D Blood Serum Level Guidelines

Who is at risk of vitamin D deficiency?

Who is at risk of Vitamin D deficiency? People who are at increased risk of low vitamin D or vitamin D deficiency include:

  • People with naturally very dark skin – the pigment in skin (melanin) acts as a filter to UVB (Ultraviolet B) radiation and reduces the amount of vitamin D the body makes.5 This group may need three to four times the amount of sun exposure that fair to olive skinned people require.4
  • People with little or no sun exposure – a range of life circumstances and occupations can lead to low sun exposure.5 People with little or no sun exposure could include those who are hospitalised, living in an aged care facility or working jobs that prevent sun exposure. Examples of jobs that could prevent adequate sun exposure include shift workers, miners, or even office workers working particularly long hours.
  • People who cover up with long robes and head coverings because of religious or cultural reasons.6
  • Breastfed babies of mothers who have low vitamin D levels. Although breast milk is the best food for babies, it does not contain much vitamin D. Since babies get their initial store of vitamin D from their mothers, if their mother has low vitamin D so will her breast milk, putting the baby at risk of low vitamin D also.
  • People with a malabsorption conditions.5
  • Older adults are also at an increased risk of developing vitamin D insufficiency in part because, as they age, skin cannot synthesize vitamin D as efficiently, they are likely to spend more time indoors, and they may have inadequate intakes of the vitamin.6 For example, when we compare a 70-year-old person with a 20-year-old that have been exposed to the same amount of sunlight, the 70-year-old makes approximately 25% of the vitamin D3 that the 20-year-old person can make.
  • Overweight – vitamin D is sequestered deep in body fat, making it more difficult for it to be bioavailable.7

How common is vitamin D deficiency?

How common is Vitamin D deficiency? Several studies have assessed vitamin D status in Australia. Although the prevalence of deficiency varies, it is acknowledged to be much higher than previously thought.

1 in 3 Australians are Vitamin D deficient. Even in Queensland a study found that 40.5% of subjects had low blood levels of vitamin D at the end of winter.8

There appears to be no significant difference in Vitamin D deficiency in Australia among men and women. Both sexes requirement for vitamin D is the same. Elderly men and women are at equal risk of vitamin D deficiency in part due to not being able to synthesize vitamin D in the skin as effectively as they age. 6