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Vitamin D

Vitamin D is nicknamed the sunshine vitamin, so you wouldn’t think that Australians would have a problem getting enough would you? But that’s far from fact especially if you protect your skin from the sun with long sleeves or other coverings (such as a hat, veil or burqa) or have naturally dark skin (eg Maori, Aboriginal Australian, Afro-American, Sudanese) or work inside all day, or are overweight.

Do you know what your levels are like?

If you haven’t had a blood test to check for vitamin D in the past 12 months, then make an appointment today with your local doctor. The human body can store vitamin D for up to 6 months only. If you had a good dose in summer, then you may be lucky and still have healthy blood levels.

Why is vitamin D important?

Many years ago, scientists used to think that vitamin D’s role in the human body was only to protect bone health by keeping blood calcium levels normal. Newer research within the last decade, now suggests that low levels of vitamin D may be related to other serious health conditions ranging from multiple sclerosis, depression, rheumatoid arthritis, insulin resistance and type 2 diabetes, and possibly some cancers. The research is not conclusive yet and is ongoing, but there are many things we do know about vitamin D.

Where do you get it?

There are two forms of vitamin D.

The most important one is produced by the sun when it hits the skin. But it is only very specific UV wavelengths that penetrate the skin to produce vitamin D.

These specific wavelengths can’t get through glass, so if you catch your sun behind the comfort of the car windscreen or a window at home, then you’re out of luck. It is unlikely that they pass through sunblock either! These wavelengths also appear to be less effective in producing vitamin D in the skin of people who are elderly and in those who are seriously overweight.

So if you are elderly or overweight or sunsmart, then you may be out of luck when it comes to relying on the sun for vitamin D.

The other source of vitamin D is a limited range of foods - cod liver oil, the fat on naturally oilier fish (salmon, trout, sea perch), regular fat cheese, table margarine, full fat milk - but very few people eat or drink enough of these sources to make up for lack of sun exposure.

What else is known about vitamin D?

  • Vitamin D levels drop during July (winter months).
  • Residents in Hobart and Melbourne have lower vitamin D than residents in other capital cities of Australia have, especially during winter.
  • Almost one quarter of adults in the sunshine state of Queensland are deficient in vitamin D. So imagine how many people have low levels in your home town.
  • People who are seriously overweight (morbidly obese) tend to have lower levels regardless of how much sun exposure they get.
  • Between 60 and 80% of people who are seeking surgery for their obesity have a defect in their vitamin D health.
  • People who have had surgery for obesity that has changed their body’s ability to absorb nutrients (eg gastric bypass surgery), people with cystic fibrosis, and people who have had part of their intestinal tract and digestive system altered due to cancer are at greater risk again.
  • Elderly people are also likely to have low levels.

What if your blood levels are low?

It is important to discuss blood test results with your own medical practitioner and dietitian. They will suggest what to do to improve the levels. They may also suggest another blood test called PTH – parathyroid hormone.

Treatment may involve supplements, sun exposure, or injections (for extremely low levels).

But I would not like to see you rushing out without sunblock and skin protection if you are at risk of skin cancer. That would not be the right thing for you to do.

If you need to take vitamin D supplements then take care because you can have too much of a good thing. Too much vitamin D might cause a build up of calcium in your blood stream that is called hypercalcemia. This in turn can cause the calcium to be deposited in places in your body where it doesn’t belong, which is very dangerous.

Although the standard advice is not take more than 80 micrograms (3200 IU) of vitamin D daily, your needs may be very, very different. Your doctor and dietitian may have suggested a higher dose than this for a very good reason – to restore seriously low blood levels quickly or because you don’t absorb much of what you take. You will need regular blood tests to check whether your blood vitamin D and PTH levels are recovering.

Never alter the doses or brands of supplements you have been recommended. Always speak with your own dietitian and doctor about any vitamins, minerals or other supplements you take.