Despite Australia’s abundant sunshine, one-third of us are deficient in vitamin D, a nutrient essential for strong bones.

Why? Number one: we’re so great at slip-slop-slapping. Using sunscreen and covering up prevents sun from reaching skin, where it converts 7-dehydrocholesterol (the vitamin D precursor produced in the skin) into vitamin D3, which then travels to the liver and kidneys to be transformed into its active form. Conversion can also be hampered by the use of personal-care products containing sodium lauryl sulphate, which washes away 7-dehydrocholesterol. Additionally, vitamin D may not convert in people who take medications or have a liver and kidney malfunction. Then there is lack of intake. Oily fish, fish roe, dairy foods, and eggs are the best sources, but you need a generous serving of each every day to come close to the recommended intake. Some foods are fortified with vitamin D, notably breakfast cereals, orange juice, yoghurt, margarine, and soy drink.

As well as bones, vitamin D is essential for muscle movement, nerve health, immune function, and to both reduce the risk of certain cancers and improve the prognosis of cancer patients: in other words, if cancer patients are replete in vitamin D before diagnosis, they have a better prognosis. MS is another condition affected by vitamin D, as it is more prevalent in patients with low vitamin D.

I believe everybody should be tested as clinically, I find a wide variety of people fall far beneath the lower end of desirable serum vitamin D levels. It’s good practice for breast-feeding mothers to supplement with vitamin D if they’re not getting enough sunlight. Older adults benefit as their skin may not be exposed to sunlight; their kidneys are less able to convert vitamin D to its active form; and they may be on drugs that disrupt the conversion of vitamin D. People who have digestive or pancreatic disorders may have lowered vitamin D intake, as these conditions hamper fat absorption. So do people with dark skin, mainly because they need to be exposed to sunlight for possibly four times as long as those with fair skin. And - while this is a little controversial - obese people as well, because their body fat binds to vitamin D molecules and stops them from entering the bloodstream.

The dosage for vitamin D depends on how low the levels are, and how quickly a person needs to return to the ideal blood level. The recommended intake for an adult over age 70 is 800IU per day; for younger adults, and pregnant and breast-feeding women, it’s 600IU per day. However, this is in people with adequate vitamin D - in clinical trials of institutionalised elderly people, doses above 10,000IU were given over three months and these just edged them into range. Supplementation needs to be supervised by monitoring blood samples, and also by a nutritionist or a naturopath to ensure the right supplement is prescribed at the right dose.

Are you at risk?
People with very low vitamin D levels are more prone to low mood, high blood pressure, migraine, some types of seizures, inflammation, musculoskeletal pain, low-back pain, and polycystic ovarian syndrome. In clinical trials when people suffering these conditions began taking vitamin D, there was a direct relationship between improvement in their symptoms and intake of supplements.

Teresa Mitchell-Paterson (BHSc CompMed, MHSc HumNut, AdvDipNat) is a member of the Australian Traditional-Medicine Society.