The Sunshine Vitamin
It feels like summer is well and truly over here in the UK and with the rapid disappearance of the sunshine comes a decline in many of our vitamin D levels.
For those that don’t know much about vitamin D, let us start with a quick background on our favourite sunshine vitamin. The reason vitamin D is commonly known as the sunshine vitamin is because it is made under the skin when exposed to the sun. Contradictorily, vitamin D is not actually a vitamin, it’s a hormone, and a lack of vitamin D can cause children to develop rickets (bone deformities) and adults to develop osteomalacia (weak bones). This is because vitamin D is involved in helping the body to absorb calcium which is essential for healthy bones. Vitamin D is also thought to have a role in the development of Seasonal Affective Disorder (SAD), a form of depression that changes with the seasons.
How Do We Get Vitamin D?
So, as we’ve mentioned, vitamin D can be synthesised by your body when your skin is exposed to certain wavelengths of sunlight. In the UK, it has been shown that UV light is only the correct wavelength to make vitamin D on exposed skin from around 11am to 3pm from April until September. This will vary in other countries depending on latitude, but this Sunshine Map should give you a rough idea. It is recommended to expose your skin to the sunshine two or three times a week for at least 15 minutes (before applying sunscreen), however it is thought that this is unlikely to maintain optimum levels of vitamin D during the winter months due to decrease in UV wavelength. Although most of the vitamin D we get is from the sunshine, it is also found in a small number of foods including: oily fish such as salmon, mackerel and sardines, eggs, and commonly fortified products such as spreads and breakfast cereals.
There are particular groups of individuals who are known to have an increased risk of developing a vitamin D deficiency. Fundamentally this is due to their limited sunlight exposure, but an individual’s skin tone also has a significant impact. Those with increased risk are pregnant and breastfeeding women, babies and young children under the age of 5, those aged 65 and over, people who cover up their skin when outside or who stay indoors for long period and people who have darker coloured skin.
Vitamin D Supplements
Although many of us are not clinically vitamin D deficient, even during the winter months, it is thought that most of us do not have an optimal vitamin D levels either. The Department of Health recommends that anyone who is known to have an increased risk of vitamin D deficiency should be taking a vitamin D supplement, however it is something that I also take during the winter months and would recommend to those who are in more extreme latitudes. When looking at supplements, the vitamin D3 (cholecalciferol) form is recommended over D2 (ergocalciferol) as the D3 is used more effectively in the body. Vitamin D is a fat-soluble hormone which means that it should be taken with a source of fat to help with absorption. However, if your vitamin D supplement comes as an oil-based capsule rather than a dry tablet you can take this at any time. If you want to read more about vitamin D then please go and have a look at the SACN Vitamin D and Health report from 2016.