Published: May 11, 2016
Author: Jennifer Joseph
According to the current Australasian Guidelines,1 the health of Australians is impaired by three main nutritional deficiencies – iodine, omega-3 fats and vitamin D.
Vitamin D is a fat-soluble vitamin, produced in our skin upon exposure to sunlight. Even though we live in sunny Australia, it has been reported that 31% of Australian adults are vitamin D deficient.2 Vitamin insufficiency is detected year-round from Brisbane down to Hobart. 3
World-leading vitamin D expert and endocrinologist at Boston University, Prof Michael F Holick says vitamin D is critically important for the maintenance of bone health throughout life.
Evidence shows that:
We should also be aware that vitamin D can help boost your immune response to bacterial and viral infections.11
Having too little vitamin D can increase our susceptibility to colds and flu, as well as our risk of developing autoimmune diseases such as multiple sclerosis and lupus.11
Additionally, if you are pregnant and have low levels of vitamin D, your baby may also be at increased risk of contracting a nasty chest infection.12
This is attributed to its role in stimulating white blood cells called macrophages, which serve to engulf infectious foreign bodies. And if that weren’t enough, vitamin D can also activate other white blood cells (T and B lymphocytes), which also play a complex part in immune defence.
Vitamin D is one of the essential nutrients, because it cannot be produced in the body.
Recent research also suggests increasing vitamin D levels may not only support healthy bones but improve immune function and reduce the risk for many conditions.14
The study by Boston University found that improving vitamin D levels could positively impact the genes associated with cancer, cardiovascular disease (CVD), infectious diseases and autoimmune diseases.14
Additionally, vitamin D is involved in muscle growth,15 it may enhance calcium absorption,16 and may play a role in preventing osteoporotic fractures that are induced by falls.17
Vitamin D deficiency is also a potential risk factor for obesity and the development of insulin resistance leading to type 2 diabetes.18 Therefore detecting and correcting a vitamin D deficiency is particularly important for those individuals with a family history of metabolic syndrome and its related complications (e.g. cardiovascular disease and/or type 2 diabetes).
There is evidence to show that vitamin D supplementation may assist in the maintenance of healthy heart muscle.19
To achieve adequate levels of vitamin D, Prof Holick says we require either increased sunlight exposure or supplementation. With Australia having some of the highest rates of skin cancer in the world, it’s important that we take sensible measures to avoid sun exposure especially at peak times, so for some populations supplementation may be a more appropriate way of getting enough vitamin D. Excessive sunlight exposure is problematic because the same UVB rays that help us make vitamin D also damage skin cells, causing skin ageing and contributing to skin cancer risk.
Many of us are unaware that, unfortunately, only a few foods contain vitamin D: oily fish, mushrooms exposed to ultraviolet light and some dairy products, but often not enough to satisfy their daily requirement. Talk to your healthcare practitioner about whether you may benefit from vitamin D supplementation.
Some of us are more inclined to having a vitamin D deficiency than others. Darker-skinned individuals, the elderly, people who wear concealing clothing and babies of vitamin D deficient mothers are all more susceptible to vitamin D deficiency. Other factors that may reduce vitamin D absorption are malabsorption syndromes (such as Crohn’s disease) and being on certain medications such as glucocorticoids and anti-seizure drugs, which can promote vitamin D destruction.10
Vitamin D deficiency is defined by a 25-hydroxyvitamin D < 50nmol/L, which is the definition used by the United States Institute of Medicine as the level to achieve for maximum bone health.
Prof. Michael F Holick recommends the following dosages:13
Note: The TGA’s recommended daily dose is 1000IU.
Speak to your healthcare practitioner for more information about Vitamin D supplementation. Make sure to always read the label and use only as directed. If symptoms persist, see your healthcare practitioner