Through ultraviolet exposure, our bodies process vitamin D when our skin is directly exposed to sunlight. One of the reasons why the vitamin D status is worrisome in Australia is that many people have taken drastic preventive measures against skin cancers, reducing sun exposure as much as possible.
Associated factors contributing to the low vitamin D levels are seasonal variations such as winter, when there is minimal sunlight, less time spent outdoors, and people cover up due to cold weather.
Use of sunblock, common window glass in homes or cars and clothing, all effectively block UVB radiation – even in the summer. People who work indoors, wear extensive clothing, regularly use sunblock, are dark skinned, obese, aged or consciously avoid the sun, are at risk of vitamin D deficiency.
More than 1 in every 3 Australian adults has mild, moderate or severe vitamin D deficiency.
The highest prevalence of vitamin D deficiency was found in Pakistan (73%;95% CI: 63 to 83%) followed by Bangladesh (67%; 95% CI: 50 to 83%), India (67%; 95% CI: 61 to 73%), Nepal (57%; 95% CI: 53 to 60%) and Sri Lanka (48%; 95% CI: 41 to 55%), respectively.
There are three main reasons for Vitamin D deficiency: diet, sun exposure and a darker skin pigmentation. South Asian cuisine is wonderfully varied with each region having its own take on traditional recipes. Unfortunately, diets in South Asian countries aren't particularly high in Vitamin D.
For most adults, vitamin D deficiency is not a concern. However, some groups — particularly people who are obese, who have dark skin and who are older than age 65 — may have lower levels of vitamin D due to their diets, little sun exposure or other factors.
Just under one in four (23%), or 4 million adults, had a Vitamin D deficiency, which comprised 17% with a mild deficiency, 6% with a moderate deficiency and less than 1% with a severe deficiency. Overall, rates of Vitamin D deficiency were very similar for both men and women.
Alarming new evidence from Curtin University has shown that up to 95 per cent of Australians have a low intake of vitamin D, which has serious implications for both our physical and psychological health especially as we move into winter.
It is found in fortified food and some supplements. Vitamin D3 is produced by sunlight on the skin. It is also found in some animal foods and supplements. Most people are not able to eat enough food with vitamin D, but most people in Australia can get their vitamin D with careful sun exposure.
This is primarily due to the fact that pigmentation reduces vitamin D production in the skin. Also, from about puberty and onward, median vitamin D intakes of American blacks are below recommended intakes in every age group, with or without the inclusion of vitamin D from supplements.
Vitamin D Levels
Healthy Bones Australia recommends a vitamin D level of at least 50 nmol/L at the end of winter and during summer higher levels are common in the range of 60-70 nmol/L. Your doctor will only test your vitamin D level (with a blood test) if you are at risk of vitamin D deficiency.
Worldwide, many countries report very high prevalences of low vitamin D status. 25(OH)D levels <30 nmol/L (or 12 ng/ml) in >20% of the population are common in India, Tunisia, Pakistan, and Afghanistan.
The further people live from the equator, the lower sun exposure (UVB exposure) and the more often they experience a vitamin D deficiency. UVB exposure decreases with degrees of latitudinal lines, and in addition to that, sunshine duration is shorter in northern countries.
The Australian government publishes recommended dietary intakes (RDIs) for all vitamins. Babies, children, teenagers and adults aged 19–50 years should have 5μg (micrograms) of vitamin D per day.
Most people can achieve adequate levels by being outdoors with typical day-to-day activities – outside of peak UV periods, that is. For those who get enough sun, Osteoporosis Australia says 400 – 800 IU of vitamin D daily will suffice. But for those who don't, they recommend taking around 800‑2000 IU a day.
According to the National Institutes of Health, almost 1 in 4 U.S. adults are considered low in vitamin D. Symptoms depend on how severe the deficiency is and the person. Vitamin D deficiency has become more common over the past several years.
In general, the two main causes of vitamin D deficiency are: Not getting enough vitamin D in your diet and/or through sunlight. Your body isn't properly absorbing or using vitamin D.
Lack of exposure to sunlight, insufficient dietary intake, and poor absorption into the body has been identified as the 3 main reasons for vitamin D deficiency2. According to reports, 63% of Pakistan's female population is vitamin D deficient, and 47% have inadequate levels of vitamin D.
Vitamin D deficiency (25-hydroxyvitamin D; 25(OH)D) is at epidemic proportions in western dwelling South Asian populations, including severe deficiency (<12⋅5 nmol/l) in 27–60% of individuals, depending on season.
The genetic influence on vitamin D levels is estimated to be around 80%, much higher than the dietary and environmental influences of around 25%.
Exposure of the skin to sunlight in the spring and summer months is the main source of vitamin D for most people in the UK. In the autumn and winter months in the UK (October to early March), there is no sunlight of appropriate wavelength for synthesis of vitamin D in the skin and we rely on dietary sources.
But there are also a number of symptoms commonly ignored or overlooked, that could be a sign you're suffering with vitamin D deficiency. These include tiredness, muscle pain, low mood and frequent coughs and colds. It's important to recognise the signs early, before they develop into anything more sinister.
Eating eggs, liver, and fatty fish like salmon, herring and mackerel will increase your Vitamin D3 levels. You can find vitamin D2 in certain foods. It naturally occurs in plants, fungi and yeast. Some foods like milk products may be fortified with vitamin D3.
Because vitamin D is fat soluble, its absorption depends on the gut's ability to absorb dietary fat [4]. Fat malabsorption is associated with medical conditions that include some forms of liver disease, cystic fibrosis, celiac disease, Crohn's disease, and ulcerative colitis [1,63].