Vitamin D: The Facts


Autumn sunshine is one of my favourite things. The air is fresh, it makes you feel good and it means it’s not raining! We got lucky with the weather this week at Outdoor Fitness and got talking about the benefits of vitamin D. We all knew a little bit about it but none of us really knew the facts with any confidence. I wanted to know more, and I love a little research project. I was surprised by what I found so I wanted to share with you what I have discovered.

What is Vitamin D? (the technical stuff)

Despite the name, Vitamin D is actually a hormone that the kidneys produce to control blood calcium concentration and impacts the immune system. To be more specific, it is a prohormone, which is a substance that the body converts to a hormone. Vitamin D is essential for healthy bones, muscles and teeth. Vitamin D is required by the body to absorb calcium and phosphate from our diets. Even in a diet rich in calcium, your body cannot absorb the calcium without the help of vitamin D.

Where does Vitamin D come from?

In the UK, we mostly get all our vitamin D from sunlight between April and September. The body creates vitamin D from direct sunlight to the skin when outdoors. Getting sunlight directly to the skin is essential, however, it is also important not to burn. Having a small amount of exposure to sunlight, without suncream or clothing, during the summer months will ensure you are well stocked.

(I had always thought that vitamin D can be absorbed by the eyes as well as the skin, but is only through the skin. While wearing sunglasses to protect your eyes from the sun is vital to optimum eye health, it is also important that you do not wear them all the time so that your eyes don’t miss out on the many health benefits that come from natural light to the eyes. As with skincare, sun is an essential element of good health but be sun safe and know your facts.)

Unfortunately, the sunlight between October to March in the UK does not contain enough UVB radiation for our skin to be able to make vitamin D. Another fact I hadn’t realised. I had always assumed that as long as the sun was shining, whatever time of year, that I would be making vitamin D. I spend a lot of time outdoors, even in the Winter, teaching classes and walking the dogs, which is good for my soul but not for my creation of vitamin D!

In the Winter we therefore need to find alternative sources of vitamin D, mainly from our diet. Vitamin D can also be found in oily fish (salmon, mackerel, herrings, sardines), red meat (high quality, unprocessed, organic) and eggs (free range). Sometimes you find some breakfast cereals, fat spreads and non-dairy milk alternatives fortified with vitamin D. Ensuring your diet is rich in these food groups will ensure you are topping up the vitamin D levels especially during the Winter months, and all year round.

How do I know if I am lacking in Vitamin D?

In most cases, the signs of lack of vitamin D are subtle and somewhat vague but the worst case scenario of a vitamin D deficiency is soft and weak bones - ricketts in children, osteomalacia in adults. Symptoms of vitamin D deficiency can include:

  1. Getting ill often

  2. Fatigue and tiredness

  3. Bone and back pain

  4. Depression (associated with)

  5. Impaired wound healing

  6. Bone loss

  7. Hair loss - specifically the autoimmune condition alopecia areata

  8. Muscle pain

As always, if you are concerned about any of these things, it is always best to speak to your doctor first. A simple blood test can confirm if you are deficient in Vitamin D.

How can I get more Vitamin D?

In most healthy adults, they will absorb enough sunlight during the summer months to be well-stocked in vitamin D. However, the NHS recommends - and I was surprised to read this - that everyone over the age of 5 takes a daily supplement of 10 micrograms of vitamin D. This can include; children, those who are pregnant or breast-feeding and the elderly. Some people have medical conditions that mean they may not be able to take as much vitamin D safely. If in doubt, you should talk to your doctor.

Taking a vitamin D supplement, eating a diet rich in vitamin D and getting plenty of sunshine does not mean you will overdose in vitamin D. However, never take more than the recommended 10 micrograms of vitamin D as a supplement as this can have some adverse reactions to your health, although the reasons are not fully understood.


So there you have it - all you need to know about vitamin D. Lack of vitamin D is incredibly common although most people are unaware they have it. Get out in the sunshine, especially in the summer months, take a daily supplement and eat a diet rich in oily fish, red meat and eggs.