* Just a note, in this post, I don’t quite clarify how to balance skin protection against the need for Vitamin D in light of medical professionals urging 24/7 sunscreen application. For reading more about this, check out this follow-up post.
You’ve probably heard of Vitamin D, perhaps used it as an excuse to sunbathe for a little longer, “to get your Vitamin D”. After all, it’s not found in many foods and your body does need sunlight for one of the steps in synthesising it. But contrary to popular belief, you don’t actually need to spend that long in the sun, because sunlight is only one step in the whole process of synthesising Vitamin D. Despite this, nearly 50% of the global population receive insufficient Vitamin D intake, and over 1 billion suffer from Vitamin D deficiency and there is little awareness of its importance or how to get it.
Why it’s important
So first, why should you care about having enough Vitamin D? Like most vitamins, it’s important to have and has a whole range of important functions and deficiency in it has been linked to increased mortality rates and a role in protecting against cancer, heart disease, fractures, autoimmune diseases, type-2 diabetes, and depression.
Part of the reason for this is that Vitamin D plays a role in aiding absorption of other important minerals, such as calcium and phosphorus. It also decreases cell proliferation and the production of new blood vessels. While those might seem like bad things, cancerous tumours result from excessive cell growth and new blood vessels to the area, so in this way, adequate Vitamin D intake can protect against cancer.
Some of the other main benefits are summarised in this open-access research paper.
How your body gets it
Hopefully you’re convinced that you want Vitamin D. You can get some from the following foods:
- Fatty fish, such as tuna, mackerel, and salmon (fat is required to absorb the Vitamin D from the food)
- Beef liver
- Egg yolks
- Foods and dairy products that are specifically fortified with Vitamin D
However, these foods contain limited amounts of Vitamin D and it is difficult to reach the recommended daily intake of 10-20 micrograms or higher.
But that’s fine, because our bodies can actually synthesise Vitamin D by themselves. We make a version called Vitamin D3 in several steps. Firstly, sunlight (generally 10-30 minutes per day depending on complexion) in the form of UVB radiation hits the skin. This creates an inert version of Vitamin D that must be hydroxylated (a process that involves adding an OH group (oxygen bonded to hydrogen) onto a molecule) firstly in the liver and then in the kidneys.
It sounds simple, yet the main reason for Vitamin D deficiency is inadequate sun exposure. Even if you do spend time in the sun, it has to be without sunscreen, as even a SPF 30 sunscreen will block 95% of the required UVB rays. Additionally, the darker a person’s skin, the more natural pigment they have and will require even more sun exposure to produce Vitamin D.
So the key is to try and balance adequate sunlight exposure against the risk of sunburn or skin cancers, in order to benefit your overall health.