Should I Supplement Vitamin D?

Whilst we’re still basking in some final rays of sunshine, we know the winter is coming.  Even though the NHS in the UK recommend we take a Vitamin D supplement year-round, this is even more important in the winter. 

But why, we hear you ask?  Well, we have all you need to know about Vitamin D.  We’ll look at it’s job and what happens when we've got low levels.

What is Vitamin D?

Despite its name, Vitamin D is actually a hormone that promotes calcium absorption.  You will likely have heard it referenced as the sunshine vitamin as it’s produced in the skin in response to sunlight (UV) exposure. 

There are two forms of Vitamin D. 

Vitamin D2 is also known as ergocalciferol which occurs in plants.

Vitamin D3, known as cholecalciferol, is created in the skin during exposure to UV light and occurs in animals.  Cholecalciferol (D3) is of greatest nutritional importance and luckily it can be obtained from the consumption of animal products that contain it.  It is defined as a fat-soluble vitamin, which means it can be stored in the body’s fatty tissue. 

Vitamin D plays an indirect role in bone health by managing calcium levels in the body.  Calcium as we know is key to bone mineralisation.  So, without calcium, bones are unable to form properly.  In studies of hip fractures in humans, there appears to be a seasonal variation; more occur during winter months and fracture patients often have low vitamin D status; when supplemented with Vitamin D and calcium, incidences of fractures often reduce.

So, if there is adequate vitamin D, calcium levels are usually maintained.

But it does so much more than look after our bones!

Vitamin D and Immune Function

Increasing evidence is demonstrating a strong association between vitamin D signalling and biological processes that regulate immune responses.  Vitamin D has been found to inhibit pro-inflammatory activity and cytokine production.  Vitamin D is also required for the production of natural killer cells which are known for killing virally infected cells.


There is growing evidence that Vitamin D deficiency could be a contributing factor in the development of both type 1 and 2 diabetes.  It is thought that cells found in the pancreas that secrete insulin contain vitamin D receptors.  Studies have also shown that when treated with a therapeutic dose, vitamin D improves glucose tolerance and insulin resistance.

Cognitive Function

Many studies are establishing a link between low vitamin D levels and cognitive decline.  Vitamin D receptors are widespread in brain tissue and it has a role in cell growth, neurogenesis, neuroprotection, detoxification, and reduction of inflammation.  Studies have also shown that low vitamin D levels in early life can affect brain development.

Low vitamin D status is often implicated in:

-          Dementia,

-          Alzheimer’s Disease,

-          Schizophrenia,

In addition, in studies involving depression and anxiety, supplementation with Vitamin D has often improved symptoms. 

Cardiovascular Disease

It has been established that low levels of Vitamin D are associated with a higher risk of myocardial infarction (heart attack).  The vitamin D axis affects vascular muscle cell proliferation (remodelling or regeneration of cells), vascular calcifications (mineral deposits in arteries and veins), inflammation and blood pressure.   

Causes of Vitamin D Deficiency

Whilst it’s often easy to consider diet is to blame for below optimal vitamin D levels, there are other factors which can contribute to low levels including:

-          Inflammatory bowel disorders – this often results in malabsorption of nutrients,

-          Pancreatic insufficiency – again this results in malabsorption of nutrients,

-          Obesity – being overweight is associated with low vitamin D levels,

And of course, in our office-based lives, lack of exposure to natural sunlight will deplete our levels!

Signs of Deficiency:

-          Regularly getting ill,

-          Fatigue and tiredness,

-          Bone and back pain,

-          Depression,

-          Impaired wound healing,

-          Bone loss,

-          Hair loss,

-          Muscle pain,

Recent data highlights that 1 in 5 people in the UK have low vitamin D levels, and so in April 2020 Public Health England updated its long-standing advice that everyone should supplement with 10 micrograms daily. 

This is advised year-round, but even more important in the winter, when we have reduced sunlight exposure. 

Vitamin D is present in a number of foods, like oily fish, red meat, liver, eggs and fortified foods, but it’s often difficult to get enough from diet alone. 

We always advocate a diet first approach, but acknowledge that we all need a helping hand every now and again.

For us, supplements can be a worthwhile addition to our daily routine.