THAT'S THE WHY:We all need iron for our bodies to function: it's an important component of haemoglobin, which carries oxygen in our bloodstream, and it has other roles too.

In excess, iron is toxic (that’s why it’s important to keep iron-containing supplements out of the reach of children), but if we run too low, we can become anaemic.

We typically get iron from foods in our diets or from nutritional supplements, but our bodies find some forms of the mineral easier to absorb than others.

Iron from animal sources such as red meat is called haem iron, and we typically take that up relatively easily.

Meanwhile, iron from plant sources is called non-haem iron, but we tend not to absorb it as well as we take up haem iron. Eating something rich in vitamin C along with the source of non-haem iron seems to be able to help absorption, but why?

It’s thought that vitamin C, which is an acid, is involved in chemically “reducing” the iron to a form that can be taken up more easily into the body.

So eating a vitamin C-rich food – maybe some berries or a glass of orange juice – along with a source of non-haem iron may help to boost absorption if the body needs to stock up.

But there are also substances that appear to hinder the absorption of non-haem iron if they are taken at the same time: they include tannins, which are found in tea.