The possibility that diets with high fibre levels could lead to mineral deficiency states in human populations was first recognised in Iran and other parts of the Middle East. In rural communities where the main source of energy was an unleavened, whole‐grain bread called tanok, male adolescents were observed to exhibit poor appetites, marked growth retardation and hypogonadism, all signs of zinc deficiency. The zinc content of the diets was adequate, but the availability of zinc for absorption was inhibited by the presence of dietary fibre and phytate.