How important is vitamin D?

Vitamin D has been getting a lot of press coverage lately — but what is it and why should we be taking it? Vitamin D supplement retailer Pharma Nord explains the need-to-know essentials about this important nutrient:

What is vitamin D?

Vitamin D is a fat-soluble nutrient that plays an important role in the body. It is widely linked with having a positive impact on our immune system, muscle function and bone health.

Once in the blood stream, vitamin D is sent to the liver as calcidiol, where it is stored until required. When it is needed, it is sent to the kidneys to be converted into calcitriol before being supplied to tissues across the body.

The main functions of calcitriol are to manage calcium levels in the blood, bones and digestive system and help cells grow, communicate and express genes. It is widely thought to have a positive impact on immunity too.

How does my body get vitamin D?

There are three main ways your body can receive vitamin D; from your diet, from sunlight or from supplements.


Vitamin D is naturally found in fish, butter and eggs. However, in the UK, we only receive 126iu of vitamin D per day from our diet — an inadequate amount for most people. As such, diet is usually not our primary method of getting vitamin D.


Sunlight is the main way we get vitamin D into our bodies. If there is enough UVB light available, the body can produce vitamin D from cholesterol. However, there are a number of factors that can interfere with this synthesis, including:

  • Season — the amount of sun we receive varies seasonally. For example, less sun is available in autumn and winter than it is in spring and summer.
  • Skin pigmentation — people with darker skin require increased sun exposure to produce the same levels of vitamin D.
  • Sunscreen and sun avoidance — physically blocking the sun with lotions or cover-ups will limit the amount of vitamin D we’re able to produce.
  • Age — as we age, we become less able to convert vitamin D from sun exposure.

These factors can reduce the level vitamin D in your body, impacting how many of the health benefits we can enjoy.


When the correct levels of vitamin D cannot be obtained from diet or sunlight, many turn to vitamin D supplements. There are two varieties of vitamin D supplements available, including D2 (ergocalciferol) and D3 (cholecalciferol). D3 is extracted from sheep’s wool, while D2 is derived from plants (usually fungi).

Of the two, D3 is often considered the best way to supplement vitamin D, as it is less toxic and more stable. Easily binding with human tissue receptors, it is an effective way of raising serum D levels.

The Scientific Advisory Committee on Nutrition (SACN) recommends taking 10μg/400iu of vitamin D each day in autumn and winter months. However, experts believe this is an insufficient amount for most people.

This is a guest article from Pharma Nord

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