It's been described as the mineral of the moment.

Millions of us are taking magnesium for a whole range of reasons. Can it help us sleep better? Sort our digestion problems? Give our busy brains a moment of peace?

In the fast-moving world of supplements, it's magnesium's time to shine.

And the industry is booming. The global magnesium market is worth nearly £3bn and that's set to nearly double over the next decade.

In a small factory, nestled in the Yorkshire Dales, huge plastic barrels of white powder are stacked up next to giant whirring machines.