Vitamin D - Power Nutrient and Health Booster

Vitamin D is the name given to a vitally important group of micro-nutrients. When activated, vitamin D becomes a potent steroid hormone, switching our genes on or off, and instructing our cells what work to do. Vitamin D's effects are varied and profound.

Serious diseases including cancer, heart-disease, diabetes and dozens more - affecting millions of people - are associated with low vitamin D blood levels, in study after study.

Medical research indicates we could become much healthier if we built up our vitamin D reserves to an optimum level. Most of us are way short.

Researchers are still only scratching the surface around vitamin D - there's much more waiting to be discovered. So let's understand D basics.

What is vitamin D?

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

1. Cholecalciferol - raw vitamin D

In our bodies, most vitamin D starts off as Cholecalciferol (ko-ler-cal-'si ferol) also known as vitamin D3. Where does it come from?.

There's a cholesterol-like compound stored in our skin, which is made in the liver. Its scientific name is 7-dehydrocholesterol, but it is often just called pre-vitamin D.

When irradiated by UV-B light, pre-vitamin D changes into vitamin D3.

UV-B light is part of the ultraviolet spectrum naturally present in sunlight whenever the sun is high (above 30 degrees or so) in the sky. When the sun is low in the sky, its light has to travel through a thicker layer of atmosphere, which absorbs nearly all the UV-B.

Clouds and heavy air pollution also absorb UV-B (most of it anyway), so direct sun through clean air works best. Even a thin layer of window glass absorbs UV-B.

There's only so much pre-vitamin D in your skin at any one time, and once it's all been converted to vitamin D3, the process stops - even if you stay in the sun.

2. Calcidiol - the storage form of vitamin D

Cholecalciferol  doesn't hang around in the body for long. It gets converted, or hydroxylated, by enzymes in our liver, to Calcidiol, the storage form of vitamin D, also known as 25-hydroxy-vitamin-D, or 25(OH)D.

Still with me? Good.

Calcidiol is stored in fat, muscle, blood, and in the liver itself, creating a vitamin D reserve. The level of this reserve can be indicated by a 25(OH)D blood test. 

Calcidiol itself has little effect on our tissues, but it is important to understand that the amount we have stored helps to regulate how much of the active form we can produce.

3. Calcitriol - the active form of vitamin D

Finally, Calcidiol is hydroxylated again, this time by enzymes in our kidneys (and in other body tissues) to the active form of vitamin D, calcitriol also known as 1,25-di-hydroxy-cholecalciferol, or 1,25(OH)₂D

Calcitriol is the active form of vitamin D, 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, under the control of the parathyroid gland in the neck, but depends primarily on the level of calcidiol in our blood.

What Causes Low Vitamin D?

Basically, we just don't get enough sunlight on our skin, so we can't make enough vitamin D3.

Because we don't make enough vitamin D3, we can't store enough calcidiol. Without enough stored calcidiol, we can't produce enough of the active vitamin D (calcitriol). 

Most of us live far from the tropics, work indoors and clothe our bodies. High-rise buildings create perpetual shade for city-dwellers. City haze absorbs most of the UV-B. When we travel to work or relax at home, we stay behind glass, leaving all the UV-B outside.

Finally when we do venture outdoors, we cover up with sunscreen to protect our skin from sun damage, aging and cancer.

Is it any wonder that we are vitamin D deficient? It's true we can obtain a little vitamin D from food, but it's not nearly enough to prevent deficiency. (See Vitamin D Sources.)

Fortunately, we can take vitamin D3 in supplement form.

As we've just seen, vitamin D produces a powerful hormone. In optimum quantities, it improves the condition and function of your immune system, brain and nerves, bones, joints, muscles - it even improves your moods. It also reduces pain, inflammation, blood sugar levels and blood pressure.

You really don't want to be without these benefits, and even more are still being discovered. See Vitamin D Benefits.

On the other hand, the health consequences of chronic vitamin D deficiency are simply devastating, including greatly increased risk of heart disease, cancer, arthritis, immune disorders, and over 30 other diseases. 

The bad news is that over half of us are vitamin D deficient - and in winter, much more than half. The good news is that the damage to our health can be easily (and cheaply) avoided.

So make yourself at home on this site. You'll find plenty of useful information here. When you're finished, you may be as enthusiastic about vitamin D as I am.

And you'll know what constitutes an effective vitamin D dose!