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Vitamin D and Immune Function

Updated: Apr 8, 2021

So, there has been a lot mentioned about Vitamin D recently. More so recently, especially in the light of Coronavirus. So, what is the low down?

Well, first and foremost the classic role of vitamin D is to maintain the health of bones and teeth. Fundamentally, it helps regulate calcium. Most of the calcium we consume gets absorbed and placed in bone. However, a small percentage stages in your bloodstream to help with other functions. Vitamin D works by helping absorb the calcium from the gut and then maintaining this balance between levels in the blood and levels in bone. If consumption of calcium falls, then vitamin D goes to the bone and extracts calcium to maintain levels in the blood, hence the increased risk of diseases such as osteoporosis and increased risk of fracture.

But what about Immunity? Studies have found that many organs, tissues and immune cells in our body posses vitamin D receptors and are, therefore, able to produce the biologically active form of vitamin D that works as this regulator in our body. We get vitamin D in two ways – firstly from UVB rays from the sun and secondly through food in our diet. When vitamin D is created via UVB rays or consumed via food it starts out as one form and is converted to the form our body needs. When it comes to immunity, vitamin D can enhance antimicrobial proteins and assist them by creating a barrier that damages microbes circulating. Furthermore, it can generate reactive oxygen species that assist in killing these microbes. Vitamin D can go further and increase the synthesis of anti-inflammatory cells as well as stopping this production. So, again, vitamin D acts as a regulator and may help active the immune system as well as suppress it to avoid excessive inflammation or an excessive immune response.

Studies have also shown that the higher the amount of vitamin D in your blood, the lower the risk of developing an upper respiratory infection. BUT and there is a big but, these studies had large variations between participants taking part in these studies. Furthermore, there was a lack of control used during the studies. It is also important to note that the medical community and we a nation are still trying to understand coronavirus. With vitamin D, there have been little randomised control studies on this subject of vitamin D and immunity as well as studies being conducted on individuals with pre existing low levels of vitamin D in their system. Also, a lot of work on vitamin D and immunity has been conducted in laboratories and trials are short term. A lot of diseases develop over a long period of time so it is unclear how vitamin D may help in these situations.

So, whilst there is a lot of anecdotal evidence that vitamin D is generally good for immunity as well as bone health, with what we know currently, there is not enough evidence and knowledge that suggest you should be taking high levels of vitamin D to ward off the risk of contracting coronavirus or any other winter bug. The effects of consuming high levels of vitamin D may be not direct as well as knowing what the long-term effects, good or bad would be. Consequently, there is no consensus yet of vitamin D status classification for immune health.

The recommendations from the NHS remain the same as they have been for a while – everyone should take a vitamin D supplement during the winter months (from October through to March) but for the reasons of maintaining bone health. These should be taken within current guidelines. When it comes to immunity and diet, there is no one golden egg, there are several nutrients that all work together to keep your immune system operating at the level it should. Remember variety is the spice of life and eat the rainbow.

If you want to know more about how I can work with you with this winter to optimise your nutrition and health through easy to make, healthy, tasty meals for all the family, then get in contact.


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