What is Vitamin D?

Vitamin D is the name given to a vitally important group of micro-nutrients which includes vitamin D3 (cholecalciferol).

When activated in the body, vitamin D3 becomes a potent steroid hormone, switching genes on and off, instructing our cells what work to do, or not do. Vitamin D’s effects are varied and profound. If we are deficient in vitamin D (as most of us are), all systems in our body operate sub-optimally.

More than 50 serious diseases including cancer, heart-disease and diabetes have been linked to low vitamin D blood levels.

What is Vitamin D?

In our bodies, we find three main forms of Vitamin D.

1. Vitamin D3 (Cholecalciferol)

There’s a cholesterol-like compound, made in our liver and stored in our skin, just waiting for sunlight to shine on it. When sunlight (UV-B) shines on our skin, this compound changes into vitamin D3.

Once it’s all been converted to vitamin D3, the process stops – even if you stay in the sun. Vitamin D3 doesn’t hang around in the body for long. It gets converted by enzymes in our liver to

2. Calcidiol – the storage form of vitamin D

Calcidiol is also known as 25-hydroxy-vitamin-D, or sometimes just 25(OH)D. Don’t scientists just love fancy names!

Calcidiol is stored in fat, muscle, blood, and in the liver itself. Together they make up our vitamin D reserve.

But this is not the active form of vitamin D. When needed for active duty, calcidiol is converted by enzymes in various body tissues, but particularly in our kidneys, to

3. Calcitriol – the active form of vitamin D

Calcitriol is a potent steroid hormone, responsible for all the powerful health benefits of vitamin D.

It’s production in the body is carefully regulated by enzymes and counter-enzymes, and controlled by the parathyroid gland in the neck.

But calcitriol production depends primarily on the level of calcidiol stored in our body tissues. If we haven’t stored enough calcidiol, we can’t make calcitriol fast enough to meet our need for it.

Vitamin D Can Transform Your Health

The activated form of vitamin D is a powerful hormone. Optimum quantities of vitamin D improve the condition and function of all body systems, including our

  • immune system
  • brain and nerves
  • bones and joints
  • muscles.

In addition, vitamin D

  • improves mood
  • reduces pain and inflammation
  • helps control blood sugar levels
  • reduces blood pressure.

That’s just a short list. There’s much more!


Take a look at Vitamin D Benefits.