What do you think of when you think about vitamins and minerals? Fresh fruits and vegetables? Fizzy vitamin C tablets? Huge multivitamin tablets that are impossible to swallow? Us too. But how much thought do you give to vitamin D?

Vitamin D is a fat soluble vitamin, meaning that like the other fat soluble vitamins, A, E and K, the body can store small amounts of it in our fat reserves. (Unlike the B vitamins and vitamin C, which are water soluble - any excess of these are lost from the body in our urine each day.)

But unlike all other vitamins and minerals, did you know that the majority of our vitamin D doesn’t come from food? Fortified dairy products, oily fish (with edible bones such as pilchards and white bait) and to a certain extent, mushrooms, all contain small amounts of vitamin D. However, the large majority of our vitamin D is manufactured by the body when sunlight hits the skin. Hence why it’s often referred to as the sunshine vitamin. 

We need vitamin D for healthy and strong teeth and bones. From October to the beginning of April when the sun is low in the sky and we tend to cover our skin, it’s recommended that we all take a 10 microgram supplement of vitamin D each day. At the moment, with us all being inside for longer, the NHS recommend carrying on with your vitamin D supplement (or starting to take one) even though the sunnier spring weather is now in full force.

Aside from our teeth and bones, vitamin D also helps to regulate our immune system, plays a role in our mental health and helps us sleep. 

In terms of immunity, vitamin D helps to modulate our immune response by playing a role in the switching on and off of some of the cells of the immune system called the B cells and the T cells. When the body is faced with an invading pathogen, these cells are switched on and help the immune system deal with the threat and signal to other parts of the immune system that they too need to switch on.

Seasonal Affective Disorder, or SAD, is a condition that causes a low mood and other mental health symptoms during the winter months. It’s linked to the low levels of natural daylight that we experience during the autumn and winter months. But it’s also linked to low levels of vitamin D, and it’s recommended that sufferers take extra special care to take a vitamin D supplement from October to March.

Studies have also found that a vitamin D deficiency can lead to an increased risk of sleeping disorders such as poor sleep quality and short sleep duration. 

Given the potential effects of a vitamin D deficiency on our immune health, mental health and sleep quality, now more than ever, it’s a good idea to make sure you’re getting enough. If in doubt, take a 10 microgram supplement daily until lockdown measures are eased. (Unless this is in the autumn or winter, in which case, carry on with your supplement until the spring.)