Why supplements can’t replace sunshine

Vitamin D is known as the ‘sunshine vitamin’, because it is synthesized in the skin when exposed to sunlight. However, as more and more people are spending less time...

Vitamin D is known as the ‘sunshine vitamin’, because it is synthesized in the skin when exposed to sunlight. However, as more and more people are spending less time in the sun, even in summer, the vast majority of vitamin D people get is from their diet, either through foods (such as dairy) or supplements. Although this is beneficial, it is not the same as getting vitamin D from the sun.

Vitamin D isn’t just as simple as one molecule, and the idea that vitamin D from foods/ supplements can replace vitamin D from the sun is another example of over-simplified science. It is better to think of vitamin D as a group of compounds.

The reason that supplements/ foods sourced vitamin D cannot replace sunshine is because the compounds are actually different. Vitamin D from food/ supplements is usually in the form of vitamin D2 or D3, where as the vitamin D you make in your skin is vitamin D3 sulphate. The body is unable add the sulphate group to vitamin D3, meaning the two molecules, although similar, are not interchangeable in the body.


Vitamin D3 Sulphate


Vitamin D3

Vitamin D has been recognised for a number of benefits, but the 6 key ones are:

  1. Maintaining strong bones
  2. Supporting the immune system
  3. Preventing the development of cancer
  4. Normalizing hormone production
  5. Keeping healthy skin
  6. Protecting the cardiovascular system

Vitamin D3 sulphate is sometimes considered to be inactivated by the sulphate group, because it is unable to be involved in calcium transport, and so its effects on bone health are largely non-existent. However, vitamin D3 sulphate is thought to be more important for supporting the immune system, preventing cancer development, and protecting the cardiovascular system than non-sulphated forms. Meaning to obtain the full benefits of vitamin D you need to obtain vitamin D from sunlight and through the diet. This isn’t to say that non-sulphated vitamin D3 isn’t beneficial for these purposes,  but it is thought to be to a lesser extent than vitamin D3 sulpate.

There has actually been very little research on vitamin D3 sulphate, although its existence and importance in our body has been known for at least 25 years. It had long been thought that vitamin D3 sulphate could only be obtained through sun exposure, but it has actually been found in raw milk. Whether it will also be in products made from raw milk such as butter is unknown, as the processing may damage/ remove it. It is possible that there are other food sources, but these have not been found yet. There are also no supplements (even fermented cod liver oil) which contain vitamin D3 sulphate.

Image courtesy of hmoong

I hope you enjoy the site, and like what we have worked hard to create, any feedback is very much welcome, after all this site is for you! Graduate of Nutrition & Food Science (Bsc) at Reading Uni.
  • Nick Evans

    Great article once again. So, how much sunlight per day is recommended? Is it more the better? Another question is does it have to be direct sunlight to the skin.? E.g Will the clouds hinder the process? Are there parts of the body which process the vit d synthesis better.? What Im saying here is we usually only have our faces, neck hands and forearms on show. I’m guessing, as I don’t fully understand what actually happens when this process takes place but does the vit d enter the blood and so would having ones chest on show be more advantageous than the hands for example?

    • Hi Nick,

      Glad you liked the article! To answer your questions:

      The amount you need will vary from person to person. fair skinned people need less sun contact than darker skinned. For example, 20 mins of direct sun on most of your upper body and face can provide plenty of vitamin D for a fair skinned person.

      More is not always better. Too much will lead to sunburn!

      Clouds will reduce the amount of sun on your skin, so on cloudy days you will need to spend longer outside.

      All skin has the same potential to produce vit D in the presence of sunlight, so no, there is no need to have your chest on show for example. However, more skin exposed will mean more vit D can be produced, and so you will need less time outside (good question!).

The Health Cloud was created in December 2011 by Craig and Morg who have been friends since high school. Our focus is to educate our readers with unbiased health articles and on the side we run our own online health shop. This website is for you, so drop us a comment or send us a tweet, we always take the time to reply!