Vitamin D for healthy bones – and for COVID-19?

Most of us know that vitamin D is important. It’s like the other things we ‘know’ – when to use the word literally, which fork goes with which course, and what Pi is. We sort of know vitamin D is good for us, but maybe not as much as we’d like. So let’s do a quick vitamin D refresher.

It’s important for our health. Among its many benefits vitamin D:

• regulates the amount of calcium and phosphate in our body, necessary for healthy bones, teeth and muscles
• helps protect us against osteoporosis, a condition that causes bones to become weak and lose their strength, making them break more easily than normal bones
• supports our immune system
• can reduce the risk of falls, important for all of us, but especially those with fragile bones or another musculoskeletal condition.

There are two types of vitamin D:

• D3 (cholecalciferol) – formed in the skin by the action of ultraviolet (UV) light
• D2 (ergocalciferol) – produced by UV light on plants and obtained through our diet.

In Australia our main source of vitamin D is sunlight. It’s important to expose our hands, face and arms to the sun every day. The amount of time needed to do this depends on where you live, the time of the year and the complexion of your skin. Because we also need to be careful that our sun exposure is safe and we don’t risk skin cancer, Osteoporosis Australia and the Cancer Council have developed a useful chart to help you work this out.

Vitamin D can also be found in small quantities in foods such as fatty fish (salmon, herring, mackerel), liver, eggs and fortified foods such as low fat milks and margarine. For most us though, it’s unlikely we’ll get enough vitamin D through diet alone.

Vitamin D – whether it’s from sunlight, food or supplements – is stored in our fat cells until it’s needed.

Why should we care about vitamin D?

First, for the reasons we mentioned above. And second, in case you haven’t felt it, it’s getting cold. Winter is upon us and we’re not exposing as much of our skin to the sun in most parts of Australia as we did earlier in the year – at least not without risking frostbite.

So we need to make sure we’re doing everything we can to get enough vitamin D during these colder months.

Most people, through every day exposure to the sun in the warmer months, will have created enough vitamin D to make it through the winter without becoming deficient. Yay!

For others however, it may take a more concerted effort to get enough vitamin D during winter. The best way to do this is to be active outdoors – e.g. going for a walk, working in the garden. You can also include foods that contain vitamin D in your diet. A dietitian can help you with this. They can also ensure your diet is healthy so that you get all the other nutrients you need.

Finally there are some people who aren’t able to get enough vitamin D through sunlight or diet, which puts them at risk of vitamin D deficiency. This includes:

• elderly people – especially those who are housebound or in residential care
• people who wear concealing clothing for religious or cultural reasons
• people with certain health or medical conditions who need to avoid the sun
• people with dark skin as their skin contains higher amounts of melanin, which inhibits the creation of vitamin D
• people in occupations where they have limited exposure to natural sunlight throughout the day – e.g. taxi drivers, factory workers, office workers and nightshift workers
• people with diseases that make it difficult to absorb enough vitamin D – e.g. cystic fibrosis, coeliac disease and renal disease.

If you‘re concerned that you may be deficient in vitamin D, it’s important to discuss this with your doctor. They can do a simple blood test to check your vitamin D levels. If you are deficient, it may be necessary to take vitamin D supplements for a period of time.

It’s important to note that if you’re not vitamin D deficient, there’s no reason to take vitamin D supplements. It’s possible to have too much vitamin D, so only use these supplements as prescribed by your doctor.

What does vitamin D have to do with COVID-19?

There have been reports that vitamin D may be useful in our fight against COVID-19, however the results of these studies haven’t been conclusive.

We know that vitamin D plays an important role in supporting our immune system. And in some recent studies people who’ve developed COVID-19 have been found to be vitamin D deficient. However these studies involved literature searches, analysis and observational studies – which are useful and provide valuable information – but can’t say with any certainty that vitamin D can help prevent people who are vitamin D deficient from catching COVID-19.

That’s because they can’t eliminate other important risk factors such as age, obesity and socioeconomic status (e.g. level of income, education, access to healthcare, housing).

However when researchers looked at the data of half a million people from the UK Biobank and adjusted for variables such as age, race, socioeconomic status and obesity, they found that ‘people with lower vitamin D have a higher risk of COVID infection, but it looks like this is explained by other risk factors and not by the vitamin D itself…our findings do not support a link between vitamin D concentration and the risk of COVID-19 infection.’ (1)

Professor Mark Morgan, Chair of the Royal Australian College of General Practitioners Expert Committee – Quality Care (REC–QC), has also been quoted as saying ‘at the moment, I’ve not seen any evidence that using vitamin D could prevent or treat COVID-19…I know that there’s a number of controlled trials that are being commenced to look into that, but we’ll have to wait for the results of those trials before we have any information.’ (2)

So at the moment, it’s a watch and wait situation when it comes to vitamin D and COVID-19. We need more information from randomised controlled trials that are able to tell us conclusively if vitamin D can protect at risk people from catching it.

And remember if you’re concerned about your vitamin D levels, discuss this with your doctor. Don’t start taking a supplement without their expert advice.

Contact our free national Help Line

If you have questions about things like COVID-19, your musculoskeletal condition, treatment options, telehealth, managing your pain or accessing services be sure to call our nurses. They’re available weekdays between 9am-5pm on 1800 263 265; email (helpline@msk.org.au) or via Messenger.

More to explore

• Shining a light on vitamin D
  National Prescribing Service, 31 July 2020
• Do vitamin D levels affect risk of infection and severity of COVID-19?
  newsGP 15 May 2020
• Exploring the links between coronavirus and vitamin D
  The New York Times, 10 June 2020
• Does vitamin D protect against coronavirus?
  The Conversation, 21 May 2020
• Vitamin D
  Better Health Channel
• Calcium and vitamin D
  Musculoskeletal Australia
• Vitamin D
  Osteoporosis Australia

References

1. Exploring the links between coronavirus and vitamin D
   The New York Times, 10 June 2020
2. Do vitamin D levels affect risk of infection and severity of COVID-19?
   newsGP 15 May 2020

Photo by Michele Blackwell on Unsplash