• 31 Jul 2020
  • 15 min 34
  • 31 Jul 2020
  • 15 min 34

There has been some recent buzz around vitamin D supplements and their role in preventing or even treating COVID-19.

In this episode, NPS MedicineWise medical adviser and GP Dr Anna Samecki talks to NPS MedicineWise senior clinical program officer and pharmacist Rawa Osman to discuss whether or not vitamin D supplements may protect people with COVID-19 from more serious health complications, possible indirect links between vitamin D deficiency and poorer outcomes for people with COVID-19, and quality use of testing principles when it comes to vitamin D.


Further reading:

NPS MedicineWise has a new article for consumers on vitamin D and COVID-19: www.nps.org.au/news/vitamin-d-and-covid-19

Transcript

Voiceover:

Welcome to the NPS MedicineWise podcast, helping health professionals stay up to date with the latest news and evidence about medicines and medical tests.

Anna Samecki:

Hi, and welcome to our NPS MedicineWise podcast. I'm Anna, a medical advisor at NPS MedicineWise. I'm joined today by my colleague and clinical pharmacist, Rawa. Hi Rawa.

Rawa Osman:

Hi Anna. Thanks for having me.

Anna Samecki:

Thanks so much for joining us. Rawa and I work together on a team here at NPS MedicineWise called the Tiger Team, which was put together specifically to address COVID-19 issues. For our listeners, Rawa, can you sum up your role outside the Tiger Team and what else you do here at NPS MedicineWise?

Rawa Osman:

Sure Anna. I'm a clinical lead at the NPS MedicineWise and as you mentioned, we work together on the COVID-19 Tiger Team. I'm also working on a range of other therapeutic topics, including a national program on opioids, chronic pain, and the bigger picture.

Anna Samecki:

Great, thanks Rawa. The topic for today's podcast is vitamin D, and the reason for this is that more people are spending time indoors than ever before. I don't know about you, Rawa, but working from home should be easy, but it's getting harder and harder, but I guess it's what we need to do to keep everyone safe. I do miss the sun, though, so we're here today to talk about vitamin D as mentioned. Rawa, there's been a bit of buzz around vitamin D lately. Can you tell us why that is?

Rawa Osman:

That's correct, Anna. There has been a buzz around vitamin D supplements and whether it protects against or even treats COVID-19. I guess that's due to the circumstances where everyone is likely to be working from home, and I'm one of those people. Because of that, we're not getting our usual dose of the sun and vitamin D. To date, though, there hasn't been any sound evidence to support the notion that vitamin D supplements may protect people with COVID-19 from more serious health complications, but there has been some studies that found lower vitamin D levels in people who have died from COVID-19.

Looking at those reviews of those studies, they actually concluded that the patient age and their state of their health, not their vitamin D levels, made them more vulnerable to poorer health outcomes. Now, adding to that, some of the leading scientific groups have combed through these studies and they couldn't really find a direct link or a causal relationship between vitamin D deficiency and an increased risk with lung infections, including those that are caused by COVID-19.

Anna Samecki:

Those are some pretty, I guess, interesting results. I guess more will come to light as the pandemic unfolds, so it's definitely a space to watch. Out of interest, Rawa, have there been any studies that have looked at vitamin D and its effect on the immune system more generally?

Rawa Osman:

As you know, Anna, vitamin D is a micronutrient which is essential to maintaining bone health and musculoskeletal health. However, recently there has been some evidence that vitamin D plays a role in our immune system. I guess the first hint of this started with reports of vitamin D receptors being present in our immune system, which could mean that vitamin D could have an effect on our immune system. There's also been some evidence that vitamin D is involved in the immune cell response to some viral and bacterial respiratory pathogens. There's also been some lab studies as well that reported an effect on the innate immune response to respiratory viruses other than the SARS-CoV-2 virus.

It has been hypothesised in a review investigating vitamin D role in reducing the risk of common cold that its mechanism is grouped into three main categories. The first category is that vitamin D helps maintain tight junctions and acts almost like a physical barrier to the entry of bacteria and viruses into the cell. The second category is that vitamin D enhances the cellular immunity through exhibiting some antimicrobial and antiviral functions. The third category is that vitamin D has been shown to have some anti-inflammatory properties by modulating the T cell response. Now that's suppressing the more generalised response and shifting it to a more targeted Th2 cell response, as well as facilitating T regulatory cells.

Also, there has been some studies that suggest vitamin D supplements could reduce the risk of acute respiratory infection in patients with low vitamin D levels. While the evidence comes from randomized trials, looking at the rapid review by the scientific advisory committee on nutrition, they found that the evidence was inconsistent and that it generally did not show a beneficial effect on vitamin D supplements on disease or infectious disease risk, I should say. There's also been some heterogeneity to the study design, the study results. Many of the included studies were in populations with pre-existing respiratory disease, which obviously affects the generalisability of those studies.

Anna Samecki:

So what you're saying, Rawa, is that there isn't a direct link between vitamin D supplementation and better COVID-19 outcomes at this stage, but are there any indirect links that we need to be mindful of?

Rawa Osman:

That's correct, Anna. The Royal Society did have a rapid review on vitamin D and COVID-19, and they concluded that it's plausible that a person with low levels of vitamin D could be more susceptible to a COVID-19 infection because of vitamin D's role in our immune system. But a direct link could not be established, really. Having said that, even thinking about vitamin D's role in our bone health, healthy vitamin D levels have the role, obviously, in optimising our bone health, particularly for patients with underlying bone disease, and possibly reducing their fracture risk. For example, if you have an older person with a bone fracture, that actually impacts on other aspects of their overall health and it increases their risk of an infection. So we really need to understand that although vitamin D may not have any direct evidence in reducing poorer COVID-19 outcomes, it may have a role to play indirectly.

Anna Samecki:

I guess the next question that comes up from this then is, what advice should health professionals be giving patients during the pandemic? Should we be telling everyone to take vitamin D supplements if there's these indirect health benefits, or should we still be saying what we've always said?

Rawa Osman:

Despite the pandemic, the recommendations around vitamin D haven't really changed that much. The main source, as you know, of vitamin D is from the sun, especially from the UVB radiation acting on the skin. We tend to get our vitamin D requirement, daily requirement, by spending about 10 to 20 minutes in sunlight. That's usually in the mid-morning or in the afternoon, because the sun is not at its peak. We also get about 10% of our vitamin D from fatty foods. Things like oily fish, eggs, and meat, but as I said, that's only a small percentage of regular intake or our daily need. It's important that people still exercise appropriate sun protection measures when they are outside, and to note the social distance requirements at the time as well. Now, another source for vitamin D is oral supplements, and these come in a variety of formulations and strengths, but it's only recommended for patients with proven vitamin D deficiency, which again raises the question of how do we really test for it?

Anna Samecki:

I think that's something I might be able to answer, I guess. As a clinician, I need to be mindful of the quality use of testing principles when testing for vitamin D deficiency. If there's any message that we want to get across today, is that we really shouldn't treat vitamin D testing as a free-for-all test. In fact, screening for deficiencies are only funded by the Medicare Benefits Schedule for selected patients who are deemed to be at a greater risk of deficiency. That includes a specific cohort of patients, including those with limited sun exposure for prolonged periods, which also, I guess, when you think about prolonged periods, those are patients who were essentially bed-bound or house-bound for long periods, or who wear clothes covering most of the skin for cultural or occupational reasons. It also includes patients with darker skin, those with fat malabsorption conditions, and those with certain chronic medical conditions such as kidney disease.

So while people are spending more time indoors due to the pandemic, it doesn't necessarily mean that they'll fall into this limited sun exposure category, particularly if they're otherwise healthy and still getting adequate sun exposure from participating in fairly regular outdoor activities. These activities can be as simple as going for a brisk walk in the morning or walking the dog in the afternoon. So I think clinicians still need to be mindful of who they're testing. In addition to that, I guess we also need to be mindful of the evidence and what it says about the benefits, or even lack thereof in some instances, of treatment and supplementation. This is, I guess, where I throw it back to you, Rawa, and ask you what the evidence tells us about the benefit of vitamin D supplementation.

Rawa Osman:

Well, Anna, the evidence for the role of vitamin D in the prevention of falls and fractures is limited, perhaps because most of the trials have disregarded the baseline concentration, focusing only or mainly on the dose instead, and/or some of the trials limited that study cohort to patients with concurrent disease states. Now there has been some meta-analysis that investigated certain doses in certain populations. I'll give you a couple of examples of those.

One is a meta-analysis that found that vitamin D supplements of 700 to 1000 international units per day reduce the risk of falls in people over 65 years. Another meta-analysis investigated the effects of vitamin D on fracture risk, and they really found mixed results, but improvements were more likely if vitamin D and calcium supplements were taken together.

Now, vitamin D supplementation is recommended for people with diagnosed moderate to severe vitamin D deficiency or those who are at high risk. For example, patients who are starting treatment for osteoporosis or those who have a diagnosis of, say, osteomalacia. In people with mild vitamin D deficiency without symptoms or complications, so that's people who don't have a concomitant disease such as rickets or osteomalacia, the evidence for vitamin D supplements and improved outcomes is quite limited and sometimes inconsistent as well. So for those patients, typically increased sun exposure is usually sufficient. However, dependent on the individual circumstances, supplementation may be considered, because it's unlikely to cause harm.

So speaking of vitamin D deficiency, Anna, throwing it back to you, how do you diagnose this in clinical practice?

Anna Samecki:

Yeah, look, I think it's important to note that vitamin D deficiency is actually asymptomatic in most cases. So diagnosis by testing is really guided by those principles that we discussed earlier, and trying to reserve vitamin D testing for at-risk individuals. If a decision is made to test an individual, vitamin D deficiency is confirmed when the level of serum 25-hydroxy vitamin D is less than 50 nanomoles per litre. It's important to point out here that healthy people with levels over 50 are not classed as being deficient. So Rawa, based on what you've told us previously in terms of evidence, people with levels over 50 who are healthy will not benefit from supplementation.

Now, back to the cohort of patients who are deficient. When we look at the levels of vitamin D, we also try to class a patient as having either mild, moderate, or severe deficiency. The reason for that is that it helps guide treatment. If we look at the Australian Therapeutic Guidelines, they actually recommend treatment for those with moderate to severe deficiency, particularly if they're symptomatic, but on the flip side, patients with mild deficiency may be given lifestyle recommendations in the first instance. As we've mentioned, being outside in the sun for 20 minutes a day is enough to give these patients their daily requirements. So if I've got a patient who's got quite a mild deficiency and they're otherwise pretty well, I will usually recommend those lifestyle changes in the first instance.

I guess, moving on from that, we also need to be mindful of this when considering the current pandemic climate. I guess this is why I would say the current recommendation for people, even with a mild deficiency who are otherwise healthy, I would just ask them to get out of the house. Practice social distancing, but try and get out of the house and get that 20 minutes in the sun when they can. I would also advise patients not to take vitamin D supplementation in an attempt to help prevent or treat COVID, because of all the reasons we've already discussed. We also need to, I guess, be aware that any medicine can be harmful and vitamin D is no exception. In certain doses, it can cause adverse effects. Rawa, as a pharmacist, what can you tell us about vitamin D and its safety profile?

Rawa Osman:

Anna, Vitamin D is generally safe. It can, like most medicines, cause toxicity, but this is generally when it's taken in really large doses or taken for very prolonged periods. Usually the effects seen with toxicity are headache, weakness, drowsiness, sometimes dry mouth. Hypercalcemia can be seen as well, sometimes vomiting. These are some of the adverse effects that can be seen. However, as I said, it's generally pretty safe to take.

Anna Samecki:

All right. Thanks for that, Rawa. Thanks for joining us today. To wrap up, can you tell us maybe in a sentence or two, what the take-home messages around vitamin D are?

Rawa Osman:

I guess the take-home message is to be mindful that more patients are now at risk of vitamin D deficiency than before, given the current circumstances, but that doesn't mean that we should be testing everyone. We really need to be mindful of who is appropriate for testing and where treatment is more beneficial.

Anna Samecki:

Thanks, Rawa. Thanks again to everyone for listening. We hope you've enjoyed today's podcast. If you have any recommendations or suggestions for our podcast, please reach out to us via Twitter or LinkedIn.

Voiceover:

For more information about the safe and wise use of medicines, visit the NPS MedicineWise website at nps.org.au.