How Vitamin D Can Help Protect Us From Viruses

This week we're sharing a blog post from our resident Nutritional Therapist and Osteopath Mary O'Leary, on how vitamin D can help protect you from respiratory viruses.




Here in the UK we tend to have low vitamin D, with levels being 50% below optimum on average. It can be found in some foods, like oily fish, but is generally hard to find in the average diet. Our biggest source is from the sun- and we haven’t had a huge amount of sun this summer. It’s recommended by Public Health England that everyone in the UK should take a supplement during the months of autumn and winter, or all year round if you have more melanin in your skin.


Why do we need vitamin D?


Vitamin D is made by our bodies from direct sunlight on our skin. From the skin, vitamin D is converted in the liver into calcidiol (this is the bit that gets measured in the blood) and then further converted into its active form in the kidneys, calcitriol. We need vitamin D because it regulates the calcium in our body needed for healthy bones, muscles and teeth, but it is also really important in protecting us from illness and viral infections. Studies have shown that people with low levels of vitamin D are much more likely to suffer from respiratory infections and flu.


Who’s at risk?


Overweight people are particularly at risk, as Vitamin D is a fat soluble vitamin: it is thought it can get trapped in fat cells and therefore show a lower level in the blood. The BAME population are at risk too, having more melanin and, therefore, an increased need for sunlight.


What are the health risks of low vitamin D?


There are many symptoms and conditions associated with vitamin D deficiency, including muscle pain, fatigue, auto-immune diseases, diabetes, rhinitis and hair loss. It’s worth mentioning that there are other factors at play in causing these conditions, such as a high sugar diet and other nutrient deficiencies. Supplementing with vitamin D may not change any of these established conditions - but there is evidence that it does provide protection from respiratory viruses.


Vitamin D and respiratory viruses


Major studies have shown that supplementing with vitamin D up to 2000 IU above Public Health England guidelines (400 IU) decreases the risk for acute respiratory infections. Best to test your levels before supplementing. This can be done privately or through your GP.


All our immune function cells have vitamin D receptors; when attacked by a virus or bacteria, our Vitamin D helps the body to modulate its immune response: this stops us overproducing anti-bodies, and can prevent the ‘cytokine storm’ as seen in some cases of Covid.


How can I make sure I’m getting enough vitamin D?


You can best provide your body with vitamin D in two ways. Firstly, spending an hour or so outside in sunny weather with arms and legs exposed will give your skin what it needs to synthesise vitamin D. However, here in the UK we don’t get enough sunlight during autumn and winter, so it’s recommended that you take a supplement from September to March – or all year round if you’ve got darker skin. Testing for Vitamin D status is easily done and many GPS will do it on request.


If you’d like some advice and guidance on supporting your immune system and overall health, we offer nutritional assessments with our Nutritional Therapist Mary O’Leary. Mary is a highly

experienced and holistic Nutritional Therapist and Osteopath; she lectured at BCOM and Oxford Brookes University, where she also worked as Clinical Education Coordinator, and co-founded the highly regarded Faringdon Clinic in Oxfordshire in 2003, where she worked until 2019.


You can book an appointment for Nutritional Therapy or Osteopathy/Visceral Osteopathy with Mary here.

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