If your eyes glaze over when scanning the car wax section, you're not alone. Alongside the tins of carnauba wax -- once the definitive choice of polish -- is a crowd of bottles, sprays and creams.

Carnauba wax is a product you may not have heard of, but you have almost certainly consumed it - it is added to sweets to stop them melting, to pills to make them easier to swallow and as a thickener ...