Q: I have an office job so spend all day inside, should I supplement with vitamin D?
In the UK, the number of people with sub-optimal levels of vitamin D is thought to be fairly widespread. There are only a few food sources of vitamin D (even less if you are vegan), so the main way to ensure we get enough vitamin D is to be out in the sunshine, which allows vitamin D to be produced within our skin. This is fairly simple if you live in a sunny climate, but in the UK we can be at a bit of a disadvantage! Plus the sun is only strong enough for our skin to produce vitamin D between March and October. To obtain vitamin D from the sun you need to expose as much of your body as possible to sunlight (between 10am and 2pm), for at least ten minutes without sun protection. It’s important though to ensure that your skin does not burn.
Here’s how it works; when the skin is exposed to UVB radiation (from sunlight) a molecule known as 7-dehydrocholesterol (derived from cholesterol) is converted to cholecalciferol, also known as vitamin D3 (the active form of vitamin D). Unfortunately, the use of sun creams, covering up our skin, spending more time indoors and a reduced intake of vitamin D rich foods, means that the prevalence of vitamin D deficiency is increasing. For this reason, Public Health England recommends that everyone supplements with 10ug of vitamin D daily.
Whilst the most recognised function of vitamin D is in maintaining bone health, it is also incredibly important for supporting the health of our immune system and may be useful for numerous other chronic degenerative diseases too. Therefore, supplementing vitamin D3, especially if you have reduced exposure to sunlight, is an excellent idea. A good maintenance dose is approximately 2500IU or 62.5ug per day.