From wood pulp in ice-cream to peat in portobellos, science has transformed how we dine. Do you know exactly what’s lurking in the grub we eat? Microbial slime and a side helping of sand doesn’t sound like much of a meal, but a startling amount of the food we eat today contains ingredients that are, at the very least, unexpected – and, at worst, dangerous, such as heavy metals from polluted soils. Then there is the thorny question of what ultra‑processed foods in our diets might be doing to us.