Thursday, 22 July 2021

Vitamin D and COVID-19


Vitamin D is important for bone, muscle and dental health but there has been no strong evidence to show that taking vitamin D supplements will make you less susceptible to COVID-19.

During the COVID-19 pandemic, many countries have been spending more time indoors than usual, because of the restrictions in place to limit transmission of the virus.

In addition to reducing the spread of COVID-19, restrictions have also helped slow down the spread of many common infectious diseases including influenza (flu). However, there are health-related drawbacks to spending less time outside.

International health authorities have been concerned that reduced exposure to sunlight has left some people vulnerable to a vitamin D deficiency.

Vitamin D is important for bone, muscle and dental health. Some recent reports have also suggested that vitamin D levels may influence risk of COVID-19 infection and severity.

What is vitamin D?

Vitamin D is an essential vitamin that helps to regulate calcium in your body, which is why it’s so important for bone health.

The source of most vitamins needed by humans come from the foods we eat. Vitamin D is different from other vitamins because it is produced when our skin is exposed to the sun (which is why it is sometime called the ‘sunshine’ vitamin). Only 10% of our vitamin D supply comes from food, like egg yolks and mushrooms, or from fish that have a lot of fatty tissue such as salmon and herring.

What does vitamin D do?

Vitamin D has an important role in helping the body absorb calcium. Calcium helps to keep our bones, muscles and teeth healthy and strong.

Throughout pregnancy, having good vitamin D levels is important for a baby’s bone development.

There is also some evidence that vitamin D plays a role in our immune responses, which researchers are trying to understand.

One clue that suggests a link between vitamin D and immunity is the presence of vitamin D receptors on the surface of human immune cells. Receptors are like a lock in a door that can only be turned with the ‘right key’. Opening the lock causes actions to occur that can change how a cell behaves. Some researchers believe that having vitamin D receptors on almost all of our immune cells means that vitamin D is able to ‘unlock’ a response in those cells and so influence our immune system activities.


Can vitamin D supplements protect me from COVID-19 infection?

Having enough vitamin D is important for your overall well being, and after your health is crucial during this time. However, taking supplements (including vitamin D) to prevent COVID-19 infection is not supported by any clinical evidence.

The best ways to avoid infection with the SARS-CoV-2 virus are to practice good hand hygiene and physical distancing, and to keep following restrictions and recommendations from the federal and state or territory departments of health.

Some international studies have reported that people who died after being diagnosed with COVID-19 tended to have low levels of vitamin D. Many of those people were older and had age-related health issues or other conditions before they contracted coronavirus. A review of available data by the National Institute of Clinical Excellence in the UK has concluded that age and health status – not vitamin D levels – made these people more vulnerable to poor health outcomes after being infected with COVID-19.

One group of research scientists from the UK said that it’s 'plausible' 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 has not been established. 

What happens if vitamin D levels in the body are too low?

It is well established that low levels of vitamin D can contribute to bones becoming more fragile and prone to breaking due to loss of bone mineral density. In mild cases, this is known as osteopenia. In more severe cases, this is known as osteoporosis, which occurs when your bones lose calcium and other minerals at a rate that’s too fast for your body to replace. 

Vitamin D deficiency in older people is also linked to poorer muscle strength and increased risk of falls.

In children, low vitamin D could lead to weak and soft bones that don’t form the way they should. This disease is called rickets. In adults, a softening of the bones is called osteomalacia.

How can one get vitamin D?

The best natural source of vitamin D is when skin is exposed to the sun’s Ultra Violet rays. 

As described previously, small amounts of vitamin D can also be obtained from food such as oily fish and eggs, but food can only make up a small portion of your daily requirement.

Some people may not be able to spend enough time in the sun or may not be able to produce vitamin D easily. Health professionals may recommend vitamin D supplements after considering individual circumstances, including whether vitamin D deficiency is present and how severe it is.


How do I know if I have a vitamin D deficiency?

Some people are more likely to have low vitamin D levels due to physical, medical or environmental factors. They include:

  • - people who wear concealing clothing
  • - people who spend long hours indoors due to their occupation or their health conditions, - including those who are housebound or living in institutions, such as aged care facilities
  • - older adults
  • - people with certain medical conditions such as obesity or malabsorption
  • - young children born to a person who was vitamin D-deficient while pregnant.


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