In Australia, about 50% of the population are deficient in vitamin D. Dr Joe Kosterich talks about vitamin D, including what it does and how it is produced, why we need it, how to balance too much sun with too little, and getting vitamin D from other sources.
In the late 1800s, there was a condition called rickets that affected coal miners. It was due to these people not having any sun exposure and they became low in vitamin D.
Hi, I’m Dr Joe.
It was sort of felt that this condition was pretty much relegated to the text books of medical history because we know more about things these days and we don’t have child slave labour in mind. Surely, this was not going to be a problem in the 21st Century.
Unfortunately, things haven’t quite panned out that way and whilst we don’t fortunately see rickets, which is a disease of the bone, we are seeing that in Australia there’s around 50% of the population who are deficient in vitamin D. Statistics for other countries do vary but it’s almost a worldwide phenomenon.
Now, how has it come to this?
Vitamin D is almost unique as a vitamin in that it seems to be somewhere between a vitamin and a hormone. It has a number of different functions within the body. It’s involved in a large number of metabolic processes. The other really interesting thing about vitamin D is that the active form is produced in the skin, and it’s produced under the influence of ultraviolet light.
This is how, unfortunately, in medicine sometimes we can avoid one problem and run head long into the next. It’s been a very good thing over the last 30 years that people have been more aware of dangers from the sun and people are less inclined to get sunburnt, so the slip slop slap is important, even more so when it’s say 35 or 40 degrees outside.
However, with the body there’s generally a right amount: too much is a problem, and too little is generally a problem as well. Even something as basic as water if we don’t have enough it’s a problem, if we have too much it is also a problem. So, what’s becoming apparent is that even with exposure to the sun: too much we know is a problem, but too little may lead us to be deficient in vitamin D.
The key roles of vitamin D are to do with bone health and brittleness of bones. It also seems to have roles in metabolism and there’s a lot of work being done about the role of vitamin D deficiency in conditions as diverse as breast cancer, colon cancer, diabetes, asthma and Alzheimer’s. It is not as simple as saying that low vitamin D causes any of those conditions, it doesn’t. But it appears to be a contributing factor and demonstrates how important vitamin D is for our body.
Alright, what’s the take home message out of all of this? Does this mean we have to throw out the slip slop slap and go back to lying on the beach for a few hours? No, it does not! What it means is we do need a little bit of sun exposure – in an Australian climate that generally means around about 5-10 minutes per day, before 10 in the morning or after 3pm. Now, that 5 or 10 minutes per day on the forearms and face – you don’t have to lie on your towel in your backyard if you don’t want to, you can if it takes your fancy but you don’t have to – that’s without sunscreen on, it’s actually the ultraviolet light that we need. If we get too much we might end up burning and getting skin cancer, if we don’t get enough then we can end up vitamin D deficient.
Can we get vitamin D from other sources? Yes, we can and there are dietary sources but the body absorbs it fairly slowly. Oily fish such as mackerel, herring, salmon and tuna are the best dietary source. You’ll need to eat around about 2½ to 3 serves per week. Probably a lot of people aren’t going to be doing that. Eggs, are good, mushrooms are the best vegan source for those that way inclined. Meat does have some vitamin D, and dairy products do have some vitamin D as well. In some instances a vitamin D supplement may be necessary.
You may or may not know that you are vitamin D deficient unless you get a test done for it. As we said at the beginning of this video, laboratory statistics are telling us that roughly 50% of the tests that they’re going are finding people are deficient in vitamin D in Australia. So, finding out your level is as simple as going to your doctor and having a test. There won’t be any specific symptoms of vitamin D deficiency. In my experience, it’s something I’ll always test if people say they’re tired. There are other reasons, of course, why people can be tired but that seems to have a reasonable strike rate.
So, to sum up, vitamin D, like most things that the body requires, has a role, it’s important. You don’t want to have too much, but too little is going to be a problem as well. And certainly, like we’re saying, osteoporosis relates to vitamin D and we touched on some of the other conditions that vitamin D has a role in.
Simple solution? A little bit – and I do underline a little bit – of sun exposure. It’s not about getting burnt; it’s not about lying on the beach for 3 hours until you’re done to a crisp. It’s about getting those 5-10 minutes in the summertime, maybe 10-15 minutes in the wintertime of sun exposure. Four days a week is probably enough, if you can do 5 or 6, that’s great, but four days a week is enough. It doesn’t have to be hard work. Dietary sources we touched on, and the other approach for some people might be supplements.
If you’re concerned, see a doctor, get your vitamin D levels checked. If they are low there’s some simple ways to boost them up help keep you healthy.

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