When the sun’s away, Vitamin D must come out to play
The summer sun has finally left us and winter is fast approaching. Now is the time to make sure your Vitamin D levels are adequate to see you through the winter months.
Vitamin D deficiency is becoming so common that it is fast becoming a major public health issue in Australia. We obtain the majority of our Vitamin D (80-100%) from skin exposure to sunlight (UVB radiation) and only 10% from food.
The main form of Vitamin D, cholecalciferol, is manufactured when ultra violet B (UVB) reacts with 7 de-hydrocholesterol on human skin. This is the same form of Vitamin D found in eggs and oily fish. Once made in the skin or ingested, vitamin D is then transported to the liver where it is hydroxylated into 25-OHD (the form that is tested in blood tests). It is then taken into the kidneys where the biologically active form of vitamin D 1,25-dihydroxy Vitamin D is made.
Think you get enough Vitamin D from driving around during the day?
Think again. Recent research suggests one main reason why we have become so deficient and that’s due to the use of broad-spectrum sunscreen, which blocks UVB rays and therefore leads to decreased absorption. Glass also blocks these rays, so if you think you get your daily dose driving around, think again. Also we have become a society where we spend more time indoors and longer hours at work, which are other reasons contributing to the increased prevalence of Vitamin D deficiency.
Vitamin D’s main function is to regulate calcium and phosphorous levels ensuring proper mineralisation of bone and bone growth and remodelling. It also has been sown to inhibit abnormal proliferation of cells and regulate immune function.
So who’s at risk of Vitamin D deficiency?
- The elderly, due to decreased exposure to sunlight, inadequate dietary intake of Vitamin D, as well as their skin being less efficient at converting UVB into Vitamin D.
- People with chronic kidney failure have an impaired ability to activate stored forms of Vitamin D.
- Individuals with gastrointestinal, liver or biliary disorders such as fat malabsorption syndrome, Crohns disease, coeliac disease, cystic fibrosis, small bowel resection and chronic pancreatitis.
- People who have naturally dark skin. The pigment in the skin (melanin) acts as a filter to the UVB radiation and thereby reduces the synthesis of Vitamin D. This group of people may need anything up to six times the amount of exposure than lighter skinned people.
- People who wear concealing clotheing.
- Night shift workers, factory works, taxi drivers
- Strict vegetarians as their diets will be lacking in vitamin D.
- Breast fed babies whose mothers have low vitamin D levels.
What happens if I don’t have enough Vitamin D?
Vitamin D deficiency has no signs of symptoms, but if left untreated, Vitamin D deficiency can result in bone disease in children, osteomalacia (soft fragile bones), and can contribute to the development of osteoporosis.
Vitamin D deficiency is also linked to conditions such as auto-immune disorders, certain cancers (prostate, breast and colorectal), schizophrenia, heart disease, stroke and psoriasis.
How can I ensure I get enough Vitamin D?
The amount of sun exposure required varies on your skin colour, where you live and the season. In Melbourne, the recommended time to spend in the sun during summer is eight minutes a day at the highest UV time, and in winter 15 minutes a day at the time of highest UV rating. The best thing to do is check the newspaper to know what time of the day this is. You also need to have as much of your arms and legs exposed as possible to have the adequate skin surface area exposed to sunlight.
Good food sources of vitamin D to supplement together with sun exposure include oily fish such as sardines, salmon, herring mackerel, cod (and cod liver oil), eggs and sun exposed mushrooms. By this I mean, if you plan to eat mushrooms that night leave them out in the sun for a few hours. It increases the amount of vitamin D in the mushrooms. Bet you learnt something new there?
Think you might not have enough Vitamin D?
If you feel you are at risk of Vitamin D deficiency, you can either ask your GP to take a blood test or I can refer you for a blood test to check your vitamin D levels. A vitamin D supplement may then be prescribed together with follow up tests used to monitor your Vitamin D levels. There is also now a vegan Vitamin D supplement on the market for those patients who follow a vegan diet. Supplements should only be taken on the recommendation of your health care practitioner
Contact us today to book your consultation
Subscribe to our newsletter
hours
Monday - Friday 8am - 7pm
Saturday 8am - 1pm
Emergencies can be seen outside of these hours
associations
