The sun, which provides essential vitamin D


If you’re reading this, it hopefully won’t be news to you that vitamin D plays an integral role in keeping you healthy. As the NHS website explains, this fat-soluble vitamin is key to regulating your body’s levels of calcium and phosphate, which are crucial to the health of your bones, teeth and muscles. 

While most of us tend to get enough vitamin D simply by spending enough time in the sun from about late March or early April until the end of September, vitamin D deficiency has been linked to various conditions, such as heart disease, diabetes and infections and immune system disorders.   

Indeed, it is the subject of vitamin D’s very complex relationship with the immune system that we would like to particularly investigate in today’s blog post. In a nutshell, how does vitamin D work alongside your immune system to help to make you feel consistently at your best? 


For a balanced immune system, it makes sense to take vitamin D 

You may have noticed that vitamin D is present and correct in our own Tonic Health sachets, which each contain 30ug – that’s 600% of the Nutrient Reference Value (NRV) – of vitamin D3, whether you opt for Lemon & Honey or Elderberry & Blackcurrant flavour. 

One very big reason why we prioritise the inclusion of vitamin D in our drinks is the help it gives the immune system to stay balanced, which could be especially useful when viruses are circulating and during cold and flu season. 

Balance is vital for the immune system. If yours isn’t active enough, you could be vulnerable to frequent infections, whereas if it is over-stimulated, you may be at heightened risk of autoimmune disease, whereby your immune system starts attacking your own cells. 


What have studies told us about the link between vitamin D and immunity? 

Cynthia Aranow, MD from the Feinstein Institute for Medical Research in Manhasset, NY observed in 2011 that “deficiency in vitamin D is associated with increased autoimmunity as well as an increased susceptibility to infection.” 

Research published in 2010 in the peer-reviewed scientific journal Nature Immunology, and led by Denmark’s Bispebjerg Hospital and Dr Marina Rode von Essen and colleagues from the University of Copenhagen, also supported the notion that people with vitamin D deficiency could be more vulnerable to infection

The research findings indicated that vitamin D is involved in a complex process in which the immune system’s T cells are ‘primed’ to help to fight infection. 

The researchers concluded that T cells create vitamin D receptors when they are primed to respond to antigens, which are substances that cause an immune response in the body. This is followed by vitamin D acting via the receptor to stimulate phospholipase C-γ1 production, with this process being required in order to activate the T cells. 

Another, much more recent study by a University of Edinburgh team shed further light on vitamin D’s effect on the immune system. According to the researchers, vitamin D prompted dendritic cells to create more of a molecule known as CD31 on their surface, with this consequently hampering the process of T cell activation. 

It’s an intriguing finding that could provide greater insight into how vitamin D helps to keep the immune system from becoming overstimulated. This – as we explained above – could be key to people’s autoimmune disease risk. 


What about COVID-19 specifically? 

It’s the disease that’s on all of our minds at the moment, and there has been an interesting hypothesis lately that vitamin D may help to lessen some of the risks associated with this coronavirus. 

Scientists from Trinity College Dublin in Ireland even went as far as stating that “the evidence supporting a protective effect of vitamin D against severe COVID-19 disease is very suggestive.” 

The NHS has said that there is not presently sufficient evidence to support the conclusion that vitamin D reduces the risk of the virus. It has advised people to consider boosting their vitamin D intake to support their bone and muscle health, at a time when many may not be getting enough of it due to spending more time indoors. 

So while there’s no doubt that vitamin D plays a significant role in immune health, the scientific jury is understandably still out on any effect on the coronavirus. Time – and testing – will tell.

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