Vitamin D is crucial for bone and muscle development and overall health. It is recommended vitamin D levels are 60–70 nmol/L at the end of summer or >50 nmol/L at the end of winter.
If vitamin D levels are too low, there may be no obvious symptoms. But without treatment, there can be significant health effects.
Health effects of vitamin D deficiency
Left untreated, a severe vitamin D deficiency can have significant health effects including bone and muscle pain, poor bone mineralisation (softer bones), rickets (bone deformity) in children and osteomalacia in adults. There has also been links with an increased risk of bowel cancer, heart disease, infections and auto-immune diseases, although more research is needed to determine whether increasing vitamin D levels can prevent these conditions.
People at increased risk
Some people are at increased risk of vitamin D deficiency.
The following groups may be more at risk of vitamin D deficiency:
- People with naturally very dark skin; the pigment in dark skin (melanin) doesn't absorb as much UV radiation.
- People with little or no sun exposure including:
- housebound, hospitalised or institutionalised Australians
- older adults
- people who wear covering or concealing clothing
- people who deliberately avoid sun exposure, such as those at high risk of skin cancer
- people in occupations with limited sun exposure, such as night-shift workers.
- Breast fed babies who fall into the risk categories above or have mothers with low vitamin D. Breast milk contains little vitamin D and infants depend on maternal stores initially (formula milk is fortified with vitamin D).
- People with a disability or chronic disease, including conditions (obesity, end stage liver disease, renal disease and fat malabsorption syndromes such as cystic fibrosis, coeliac disease, inflammatory bowel disease) or medications that affect vitamin D metabolism.
Individuals in these at risk groups concerned about their vitamin D levels should speak with their doctor to determine if dietary supplementation, rather than sun exposure is appropriate. Vitamin D levels can be checked with a simple blood test.