Pop a Pill if the Sun Doesn't Shine on You

The Scientific Advisory Committee on Nutrition — a UK government body that advises on public health issues relating to nutrition — recently published a draft recommendation stating that almost every adult and child in the UK should take a vitamin D supplement.

Let’s take a look behind the headlines and find out a little about vitamin D, and how chromatography is used to analyse plasma for vitamin D. First, why do we need vitamin D?

What is vitamin D used for?

Vitamin D plays a crucial role in the body — it helps regulates the amount of calcium in our body which is used to build and maintain our skeleton. A lack of vitamin D in children can cause rickets, a painful condition that leads to bone deformities such as bowed legs; in adults the same condition leads to weakened bones and an increased risk of osteomalacia — a softening of the bones.

Vitamin D is also linked with the functioning of many different genes and there is some research that suggests the vitamin plays a role in fighting some diseases.

In the strictest sense, vitamin D is not really a vitamin at all. Vitamins are essential nutrients that cannot be made in the body — we get them from our diet — but we make vitamin D in the body.

The ‘Sunshine vitamin’

Humans get our vitamin D from two sources, diet or sunshine. It is very difficult to get the amount of vitamin D we need from our diet. The main sources are oily fish, offal and fortified foods like breakfast cereals — but the amounts we need to eat to get a recommended dose means we cannot rely on foods to get the vitamin D we need.

Instead, our main source of vitamin D is from sunlight, or more specifically the UVB light we get from the Sun. When UVB is incident on the body it starts a process that eventually ends up making vitamin D. And the problem in the UK is the lack of UVB in the sunlight we get.

UVB is scattered as sunlight passes through the Earth’s atmosphere — and at latitudes away from the Equator, the sunlight passes through more of the Earth’s atmosphere — meaning the UK gets less UVB than the countries near the Equator.

The amount of UVB the UK gets is sufficient in the summer months for most people to make enough of the vitamin D needed; but the UK doesn’t get enough sunlight in winter to maintain our vitamin D levels. Hence the need for a top-up.

Measuring vitamin D

Vitamin D is difficult to analyse in blood serum, and most tests usually rely on a precursor or metabolite concentration. Some of the problems with vitamin D analysis are discussed in this article, Development of a Highly Selective LC/MS Assay for Vitamin D Metabolites at Chromatography Today.

Image by AdinaVoicu via Pixabay.