With approximately one in four Australians deficient in Vitamin D, it’s important to understand who is at risk and whether supplementation through diet or sun exposure is necessary. (1)
Why is Vitamin D Important for Health?
Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, along with multiple other biological effects. It’s important for strong and healthy bones and preventing diseases such as osteomalacia osteoporosis and rickets and acts more like a hormone, with most nearly every cell containing a receptor. It is also important for a strong immune system, with research showing vitamin D deficiency is linked to increased risk of viral infections and respiratory tract infections (think sore throats and the common cold). (2) Emerging research has also identified a link between Vitamin D deficiency and mental health disorders such as depression, seasonal affective disorder (SAD) and schizophrenia. (3)
Who is at Risk of Deficiency?
In winter, rates of Vitamin D deficiency are particularly high for those living in the south eastern states of Australia, such as Victoria and ACT, where nearly one in every two people (49%) are Vitamin D deficient in winter compared with only 16% and 13% respectively in summer. In contrast, Vitamin D deficiency remains relatively low in winter for those in Queensland and the Northern Territory. The following groups are at an increased risk of deficiency:
- Elderly and housebound or in residential care
- Naturally dark skinned (darker skin reduces the penetration of UV light)
- Avoiding the sun for skin protection or due to medical advice for other medical reasons
- Covering your body for cultural or religious reasons
- Affected by other medical conditions that can impact on your ability to absorb / process vitamin D
- Babies of vitamin D deficient mothers
Whilst a deficiency can show no signs initially, potential symptoms include:
- Getting sick often (such as viral infections)
- Slow wound healing
- Fatigue and tiredness
- Bone and back pain
- Hair loss
- Muscle pain
How to Test for a Deficiency:
A vitamin D blood test from your GP can be performed. It is not usually a part of a routine blood test and would need to be requested. Levels will usually be lower towards the end of winter and higher towards the end of summer (due to sunlight). Vitamin D levels are considered healthy at 50 nmol/L or higher (however some integrated practitioners would argue that optimal levels sit above 80nmol/L) The national cutoffs are below: (4)
- Adequate levels: ≥50 nmol/L
- Mild deficiency: 30 – 49 nmol/L
- Moderate deficiency: 13* – 29 nmol/L
- Severe deficiency: <13* nmol/L
How to get more Vitamin D
Just get more sun right!? Well the issue is that in Australia we have very high rates of skin cancer (Melanoma cancer is the third most common cancer with one in three people affected by the age of 70). (5) It can be so confusing balancing out vitamin D needs with sensible sun protection. Advice very much also depends on where in Australia you live. Here are some general rules:
- If UV Index is below 3, no sunscreen is needed (unless spending long periods outdoors).
- Most smartphone weather apps will show the local UV Index.
- In summer around 5 minutes of face and arm exposure per day is needed for adequate Vitamin D.
- In winter around 17-25 minutes per day on most days is needed (2-4hr per week) for adequate Vitamin D.
Most people only get 5-10% of their Vitamin D from food sources. Fish, eggs and UV-irradiated mushrooms are good sources. Additionally, some types of milk are fortified with vitamin D. A great health hack is to expose mushrooms to sunlight for a minimum of 20 minutes to significantly increased their bioavailable vitamin D content. Vitamin D-enhanced mushrooms contain high concentrations of vitamin D2, which is bioavailable and relatively stable during storage and cooking. (6)
Vitamin D Supplements:
Those with low Vitamin D levels may be required to take a Vitamin D supplement, usually D2 or D3 (preferred) form in liquid, drops or capsule form. There is conflicting research looking at the effectiveness of Vitamin D supplementation, whilst it may not be dangerous to take in recommended doses, it’s effectiveness is inconclusive. One Meta analysis did find a positive association with supplementation and reduced risk of acute respiratory tract infections (7)
Ultimately sensible sun exposure, followed by a diet rich in Vitamin D containing foods, then finally supplementation is recommended for optimal vitamin D levels.
Amelia Phillips is a nutritionist and exercise scientist who has helped thousands live a healthier life through optimised nutrition and targeted supplementation.