Vit D deficiency – in this sunny country, how can it be?

Sunset on sea in Maldives

by Diana Arundell

The prevalence of vitamin D deficiency in our sunny country may be hard to believe, however it is not only a reality but it’s a growing issue putting many Australians at risk of developing serious health conditions.

Some of the conditions associated with vitamin D deficiency include increased risk of breast or bowel cancer, cardiovascular disease, allergies, lowered immunity, autoimmune disease and exacerbation of osteoporosis.

There are two main forms of vitamin D and these are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). D2 can be found in food fortified with vitamin D and cheaper supplements, whereas D3 is found in food derived from animal products, high quality fish oil and supplements. Vitamin D3 is the better form of vitamin D as it increases blood concentration of vitamin D more than the less effective D2 version. Sunshine and D3 supplementation increase levels of Vitamin D in the body significantly more than dietary sources. These days many Australians spend much more time indoors (working in offices, relaxing in front of screens, fear of skin cancer) than we ever used to and when we do go outside, we slip, slop and slap so that our skin is protected from any sun exposure as well as any vitamin D absorption. Sunshine needs to hit the skin directly, without sunscreen and not through a glass window, for the body to manufacture vitamin D effectively. We need 15-20 mins of direct sunlight on our skin most days to maintain optimal levels of vitamin D.

So how does sunshine make vitamin D? Ultraviolet B (UVB) rays stimulate vitamin D precursors in the body to make an inactive form of vitamin D that is then activated via liver and kidney mechanisms. The activated form of vitamin D then attaches to vitamin D receptors located in many organs and tissues of the body and begins its involvement in various health promoting pathways.   

Much of the research about the protective mechanisms of vitamin D uses minimum blood levels of 80nmol/L so this is the minimum level to aim for in blood tests. It’s also important to consider the time of the year that the vitamin D level is tested, as it’s most likely to be naturally higher in the warmer months when we are spending more time out doors and likely to be receiving more sunlight. Vitamin D levels are naturally going to drop during the winter months as we spend more time indoors and even when we are outdoors, our skin is covered up with warm clothing. Ideally we need to build up our vitamin D stores in summer to support us through winter when the levels will naturally drop. Unless required for other reasons, testing for vitamin D levels in April makes sense as this gives an indication of the blood levels at the end of summer when it should be at it’s highest. If levels are already suboptimal at the end of summer, supplementation through the winter months is recommended.

In Australia where it appears that too much sun is causing skin cancer, how can we be vitamin D deficient? Again optimal health comes back to balance, and both extreme sun exposure and extreme sun avoidance can lead to significant health issues and both have been associated with increased risk of different forms of cancer. It’s not necessary to burn in the sun to get adequate vitamin D. 15 mins of morning or afternoon sun directly touching the larger skin surface areas (preferably not the face) is a good start. After that time, sunscreen can then be applied to stop sunburn. Children also need some direct sunlight to hit their skin, once again not enough to create sunburn, however some direct sunlight before sunscreen is applied will help vitamin D status.

Some of the key actions of vitamin D include maintaining bone mineralisation, anti-diabetic, immune-modulatory, supports cognitive function, regulates cell differentiation and proliferation, supports cardiovascular health just to name a few. Seasonal affective disorder (SAD) and depression are also linked to low levels of vitamin D.

Clinical studies show that supplementing with vitamin D alone or in combination with calcium, can improve bone quality and improve muscle strength and balance, even reducing the risk of falls and fractures in the older population. Increasing evidence is linking low vitamin D with various autoimmune conditions such as rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, and systemic lupus erythematosus. Altered vitamin D metabolism or deficiency may contribute to cognitive decline and degenerative brain disease in the elderly.

The studies emerging regarding vitamin D and breast cancer propose that sufficient levels of vitamin D may be associated with a reduced risk of breast cancer regardless of the hormone receptor status of the tumour. The aggressiveness of the disease may also be reduced with adequate levels of vitamin D.

The effects of vitamin D supplementation in children have also been studied and the results are showing promising signs in the area of boosting immune function as well as reducing allergies including eczema.

Treating vitamin D deficiency and indeed preventing it can be simple and inexpensive. Sufficient levels of vitamin D can be achieved by responsible sun exposure and 800-1000IU of vitamin D consumed via the diet or supplementation. Dietary sources include eggs, dairy, cod, tuna and herring, however sunlight and supplementation appear to be the most effective way to improve deficient vitamin D levels. Even though vitamin D is a fat-soluble vitamin and toxicity is rare, blood levels needs to be monitored if taking high doses longer term. There are possible interactions of vitamin D with certain medications such as calcium channel blockers, therefore prescription and dosage instructions should come from a nutritionally educated healthcare practitioner. A large number of Australians are taking cholesterol-lowering medications and these may reduce the absorption of fat-soluble vitamins including vitamin D, therefore supplementation ideally should be taken either 1 hour prior to taking the drug or 4–6 hours afterwards. There also appears to be a link between low vitamin D status and high cholesterol but the mechanism behind this is yet to be fully understood.

Diana Arundell is a university-qualified naturopath and consults from her Avoca Naturopath clinic.
She has a special interest in fertility and pregnancy health, digestive health, immune function and family wellness programs. She was a nutrition lecturer at Macquarie University for 10years, and is an accredited Journey Practitioner. www.avocanaturopath.com.au