Why Are Australians deficient in Vitamin D?

Age related illnesses, General, Immune, Vitamins | August 15, 2016 | Author: Naturopath

Why Are Australians deficient in Vitamin D?

Low vitamin D status is common worldwide, including sun abundant countries where protective clothing, use of sun screen, or sun avoidance behavior is a part of everyday life. For the Australian population, the need for strong sun protection habits to minimize the risk of skin cancer far outweighs the importance of soaking up the sun to get enough vitamin D..

What is vitamin D and why is it so important?

shutterstock_329698526Despite the name, vitamin D is not a vitamin at all. Vitamin D is actually a hormone that acts as a chemical messenger delivering important information to cells throughout the entire body. Our body relies on hormones to function properly. Hormones are released from specific organs or glands in our body, and travel through our bloodstream to send messages to our cells. Each cell in our body has specific hormone receptors; including receptors for vitamin D. Sometimes the body functions like a radio station but instead of broadcasting music that gets picked up by receivers, the body broadcasts chemical messages from hormones that are picked up by receptors on cells. Good vitamin D status is absolutely essential for good bone health, but the actions of vitamin D also play an important role in a number of other diseases that are not related to skeletal health. Solid scientific evidence has proven that vitamin D status plays an important role in other health outcomes including cancer, auto-immune disease, cardiovascular disease, diabetes and respiratory disorders like asthma and chronic obstructive respiratory disease.

So why do we refer to such an important hormone as a vitamin? The simple answer is that almost 100 years ago, the chemical structure of this particular steroid hormone was found to be similar to the known chemical structure of some vitamins, so when the compound was first discovered it was given the name “vitamin D”, even though it was a hormone. The name stuck and even today we refer to this essential hormone as a vitamin.

How can Australians get enough vitamin D if we have to avoid the sun?

It’s true that vitamin D is mostly synthesized from precursors in the skin after direct exposure to ultraviolet B (UV-B) radiation from the sun. Once vitamin D is activated in the skin after UVB exposure from the sun, it is transported throughout the blood to the liver, and then to the kidney. Chemical messages are then released from these organs and received by the various cells throughout the body.

But what if we need to protect our skin from the sun in order to prevent cancer?shutterstock_98586479

Although the most direct way to get vitamin D is from sun exposure, vitamin D can also be obtained from the diet. Significant natural sources of vitamin in food include fatty fish (cod liver oil, mackerel, salmon, and sardines), eggs yolks, and mushrooms if they are treated with UV rays. In some countries like Canada and Norway, dairy, grain products and infant formula are fortified with vitamin D. In Australia, the Food Standards Agency has decided that manufacturers must add vitamin D to edible spreads like margarine. Vitamin D can also be obtained through the use of supplements, but caution is advised if combining with some prescription medications to avoid interactions.If you are otherwise healthy and do not take prescription medication, it is safe to speak to your naturopath about vitamin D supplements.

Who is at greatest risk for vitamin D deficiency and what are the consequences of vitamin D deficiency?

Vitamin D deficiency impacts the health of humans from the cradle to the grave 

For the developing fetus, vitamin D is transferred from the Mother’s placenta in utero. This means that the vitamin D status of the pregnant Mother is crucial for the baby throughout pregnancy and immediately after birth. Although breastfeeding is highly recommended as an essential source of nutrients, breast milk is in fact, a poor source of vitamin D. Infants born with vitamin D deficiency who are exclusively breast fed with no sun exposure are at increased risk of developing rickets – a childhood bone disorder in which bones soften and become prone to fractures and deformity. Pregnant women who are vitamin D deficient can prevent neonatal vitamin D deficiency and the risk of rickets via vitamin D supplementation.

Various studies in Australia have revealed - 

  •  low vitamin D during pregnancy is a risk factor for the development of postpartum depression symptoms.
  • 16% of pre-school children did not have sufficient vitamin D levels.
  • In school aged children, vitamin D deficiency can decrease bone density which has been linked to an increased risk of bone fracture and osteoporosis later in life.
  • 31% of 14 year olds and 40% of 17 year olds did not have sufficient vitamin D levels. Adequate vitamin D status may be important in adolescence in order to optimize calcium absorption and for continued skeletal growth.
  • one-third of the adult populations aged 25 years and older do not have sufficient vitamin D levels.

Since humans reach peak bone mineral density around 25-years of age, vitamin D deficiency in the adult population may have important consequences for other health outcomes.

Vitamin D is a powerful anti-inflammatory, so having a good vitamin D status may have a positive impact on non-bone related diseases including asthma and allergy, auto-immune disease, diabetes and heart disease, just to name a few. The elderly population is particularly vulnerable to frailty, vitamin D deficiency, and bone fractures. As we age, our skin loses the ability to synthesize vitamin D from the sun. Many elderly people have a reduced quality of life that may include assisted living, reduced appetite and poor nutrition, and reduced mobility. Elderly people are often more prone to mobility related accidents including falls. Data from southeastern Australia shows that patients presenting to hospitals with bone fractures also commonly have poor vitamin D status. The connection between vitamin D deficiency and bone fractures in the elderly population is strong.

shutterstock_462025597Prescribing sunshine: How can Australians be sun safe while ensuring they get enough vitamin D?

With so many competing sources of information in this digital age, it can be difficult to know where to turn for guidance related to health and disease, and vitamin D status in the Australian population is certainly no different. A recent Australian study of attitudes, practices and knowledge of general practitioners (GPs) with regards to vitamin D seems to highlight the confusion within the medical practice. Most GPs believed that a person of average sun sensitivity required 10 min of direct sun exposure during summer in peak UV times. Some GPs believed that people required 30 min of direct sun. While other GPs advised their patients to use sun protection at all times – even during the winter.

But all hope is not lost! A vitamin D position statement of the Australian and New Zealand Bone and Mineral Society and Osteoporosis Australia has been endorsed by the Australasian Paediatric Endocrine Group, Royal Australasian College of Physicians, and Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Here’s what it says:

Vitamin D deficiency can be treated with daily low-dose vitamin D supplements, although barriers to adherence have been identified. High-dose intermittent vitamin D can be used in children and adolescents. Treatment should be paired with health education and advice about sensible sun exposure. Infants at risk of low vitamin D should be supplemented with 400 IU vitamin D3 daily for at least the first year of life.”

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References
1. Daly RM, Gagnon C, Lu ZX, Magliano DJ, Dunstan DW, Sikaris KA, et al. Prevalence of vitamin D deficiency and its determinants in Australian adults aged 25 years and older: a national, population-based study. Clin Endocrinol. 2012;77(1):26-35.
2. Rodda CP, Benson JE, Vincent AJ, Whitehead CL, Polykov A, Vollenhoven B. Maternal vitamin D supplementation during pregnancy prevents vitamin D deficiency in the newborn: an open-label randomized controlled trial. Clin Endocrinol (Oxf). 2015;83(3):363-8.
3. Zhou SJ, Skeaff M, Makrides M, Gibson R. Vitamin D status and its predictors among pre-school children in Adelaide. Journal of paediatrics and child health. 2015;51(6):614-9.
4. Robinson M, Whitehouse AJO, Newnham JP, Gorman S, Jacoby P, Holt BJ, et al. Low maternal serum vitamin D during pregnancy and the risk for postpartum depression symptoms. Arch Women Ment Hlth. 2014;17(3):213-9.
5. Black LJ, Burrows SA, Jacoby P, Oddy WH, Beilin LJ, Chan She Ping-Delfos W, et al. Vitamin D status and predictors of serum 25-hydroxyvitamin D concentrations in Western Australian adolescents. Br J Nutr. 2014;112(7):1154-62.
6. Mow TC, Stokes CM, Sutherland AG. Patients presenting with fractures are likely to be vitamin D deficient: are we getting enough sun? Anz J Surg. 2015;85(10):766-9.
7. Youl PH, Janda M, Kimlin M. Vitamin D and sun protection: The impact of mixed public health messages in Australia. Int J Cancer. 2009;124(8):1963-70.
8. Bonevski B, Girgis A, Magin P, Horton G, Brozek I, Armstrong B. Prescribing sunshine: a cross-sectional survey of 500 Australian general practitioners' practices and attitudes about vitamin D. Int J Cancer. 2012;130(9):2138-45.
9. Paxton GA, Teale GR, Nowson CA, Mason RS, McGrath JJ, Thompson MJ, et al. Vitamin D and health in pregnancy, infants, children and adolescents in Australia and New Zealand: a position statement. Med J Aust. 2013;198(3):142-3.

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