Crazy as it sounds today, once upon a time the ‘perfect diet’ was thought to be 12% protein, 5% minerals, up to 30% fat and the rest as carbohydrate! 

Thankfully, we’re no longer prescribed a diet of meat and potatoes. Today, we know that our bodies require a wide range of other nutrients. These nutrients sustain life, yet our body can’t make them alone -  that’s what food is for!

However, there’s one interesting exception to this rule. Unlike other essential vitamins that are provided by the diet, the body can also produce Vitamin D from sunlight. 

It’s super fascinating! Discover how our bodies get Vitamin D, what it does and why it’s so essential to overall health. 


That’s right. In fact, it’s a bunch of similar chemicals that are collectively called ‘cholecalciferol’. Cholecalciferol is inert in the body, hence why you hear of ‘inactive’ forms of Vitamin D.  Our body needs to convert this cholecalciferol into the active form of Vitamin D known as ‘calcitriol’. Check it out:

Our body gets cholecalciferol (the inactive Vitamin D) from two different sources. We get most of our Vitamin D from sunlight, with smaller amounts coming from the diet. 

How Do We Get Vitamin D From Sunlight?

Our skin naturally contains a substance called ‘7-dehydrocholesterol’. When our skin is exposed to sunshine or UV light, this substance is converted into Vitamin D3. We can also get a little bit of Vitamin D from certain foods, such as oily fish, eggs and full fat dairy.  

Whether this Vitamin D comes from our skin or the diet, it needs to be processed by the liver and kidneys before reaching its final activated form of calcitriol. 


From here on in, I’ll be talking about the activated form of Vitamin D - calcitriol. Technically, calcitriol is a hormone and it does many amazing things in your body!

Initially, Vitamin D was discovered for its role in maintaining skeletal health. Scientists first discovered that dogs who were raised indoors and deprived of sunlight developed rickets - a bone disease that was remedied by Vitamin D through sunlight or cod liver oil.

Since then, science has discovered that Vitamin D is involved in so much more than bone health:

Intestinal Absorption

Vitamin D enhances our absorption of calcium from the intestines.

Calcium & Phosphorus Levels

The body requires a certain level of calcium and phosphorus in the blood. When levels drop off, Vitamin D kicks in and helps our body to keep things nice and stable. 


Vitamin D has several functions that support a healthy immune system. 

Brain Development & Mood

Low Vitamin D levels have been associated with mood disorders and depression.

Autoimmune Disorders

Some research has made a connection between multiple sclerosis and Vitamin D deficiency.

Bone Health

As Vitamin D helps to maintain calcium levels in the blood and enhance the absorption of dietary calcium, it’s very important for strong skeleton!

Cancer Prevention

Certain studies suggest that Vitamin D may help to prevent some forms of cancer.


Whilst a generally healthy body can make plenty of its own vitamin D from sunlight, in reality things are a little tricker than this! Most people work indoors during peak sunlight hours and many parts of the world experience long seasons of darkness. Thankfully, there’s other options we can use! 


This is a great option if you have high skin cancer risk, live in a part of the world that doesn’t get much sunlight or don’t get much vitamin D from your diet. HINTS: look for biologically active forms Biologically active form of Vit D (vitamin D3) (1a,25(OH)2-vitamin D3). It is available in both tablet or capsule form and can be taken at any time of the day. 

(There’s just a few precautions to consider before supplementing with Vitamin D. Check with a trusted health practitioner if you’re taking digoxin, thiazide diuretics, have heart disease, hyperthyroidism, lymphoma, liver disease, hormonal disorders, high blood calcium levels and a number of other medications. We recommend also getting your blood levels measured before taking a supplement and monitoring thereafter.)

I also recommend having a blood test before supplementing with Vitamin D. If you’re Vitamin D is low, it’s a good idea to monitor your levels during supplementation until you’re back within  a healthy range. 


It’s very difficult to get our Vitamin D requirements from diet alone, however we can top up a little with the following foods:

  • Oily fish
  • Beef liver
  • Cod liver oil 
  • Egg yolks
  • Fortified food


Safe Sunlight Exposure

Sunlight exposure upon bare skin is our body’s primary method of getting Vitamin D. It doesn’t take long and you don’t need much - particularly in Summer. However, the benefits of sunlight exposure do need to be viewed in light of the risks of sunburn, particularly in countries where skin cancer risk is high.

There is no need to tan or burn in order to activate Vitamin D3 in your skin. As a general guideline, expose your bare skin for approximately half the time required for your skin to start getting pink or burning. This will change depending on the time of day, your location and skin color. You can also optimize this time by exposing a larger surface area of your body, such as your back. 

As you can see, Vitamin D has quite a journey from its original start in your skin or food to where it eventually works its magic in your body! Have you had any experiences with Vitamin D deficiency, and what did you do to help it?