When Canadian science graduate Christopher Charles visited Cambodia six years ago he discovered that anaemia was a huge public health problem.

In the villages of Kandal province, instead of bright, bouncing children, Dr Charles found many were small and weak with slow mental development.

Women were suffering from tiredness and headaches, and were unable to work.

Pregnant women faced serious health complications before and after childbirth, such as haemorrhaging.

Ever since, Dr Charles has been obsessed with iron.