Even though Australia has one of the highest UV radiation levels in the world and is well known for its abundance of sunshine, research has found many people are deficient in vitamin D because of the amount of time they spend indoors.
The prevalence of vitamin D deficiency amongst those with dark skin, or those who cover their skin for religious reasons, can be directly attributed to extremely low sun exposure, which is the main source of vitamin D in Australia.
Vitamin D deficiency occurs when your body doesn't get enough vitamin D for healthy functioning. More than 1 in every 3 Australian adults has mild, moderate or severe vitamin D deficiency.
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.
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.
An unhealthy diet and malnutrition may cause both vitamin D and vitamin B12 deficiencies together. Vitamin D deficiency may damage the stomach's mucosal (inner lining) layer. This may cause generic nutritional deficiencies, including vitamin B12 deficiency.
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].
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.
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. For example, it has been estimated that 490 million individuals are vitamin D deficient in India [2, 17].
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.
In summer, exposure is best at mid morning or mid afternoon (outside peak UV times). In winter, longer exposure times are needed, preferably around midday. It is important to balance the need for sun exposure to produce adequate vitamin D, at the same time avoiding the risk of skin damage from too much exposure.
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.
Vitamin D insufficiency may relate to higher levels of anxiety and depression, in turn contributing to the elevated risk of psychosis in this population.
Signs of Vitamin D Deficiency and Depression. The National Health and Nutritional Examination Survey confirmed that people with vitamin D deficiency are at significantly higher risk of depression than individuals with normal levels.
Vitamin D helps regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones, teeth and muscles healthy. A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain caused by a condition called osteomalacia in adults.
Growing evidence has demonstrated that vitamin D has a role in sleep regulation [12]. Specifically, vitamin D deficiency (VDD) can increase risk of sleep disorders and is associated with sleep difficulties, shorter sleep duration, and nocturnal awakenings in children and adults [13,14,15].
The best sources are the flesh of fatty fish and fish liver oils. Smaller amounts are found in egg yolks, cheese, and beef liver. Certain mushrooms contain some vitamin D2; in addition some commercially sold mushrooms contain higher amounts of D2 due to intentionally being exposed to high amounts of ultraviolet light.
Older people are prone to develop vitamin D deficiency because of various risk factors: decreased dietary intake, diminished sunlight exposure, reduced skin thickness, impaired intestinal absorption, and impaired hydroxylation in the liver and kidneys (11–13).
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.
in winter in the southern parts of Australia, where uV radiation levels are less intense, people may need about two to three hours of sunlight to the face, arms and hands, or equivalent area of skin, spread over a week to maintain adequate vitamin D levels.
The researchers took into account the amount of clothing and the season of the year. In spring and summer, 25 percent of the body (the hands, face, neck and arms) is exposed to the sun, and in these seasons, about 8 to 10 minutes of sun exposure at noon produces the recommended amount of vitamin D.
Having inadequate levels of vitamin D may correlate with unintentional weight gain. A study on women over the age of 65 found that participants with a lower vitamin D level experienced more weight gain. A systematic review of 23 different studies found similar associations between vitamin D deficiency and obesity.