How are foods fortified?

The most common method of fortification is to add premix to foods such as flour or salt. Currently only 28% of the world's wheat is adequately fortified, as well as very little of the world's rice or corn supply. The process of fortifying staples is quite simple, generally involving nothing more complex than spraying salt with iodine, adding a dry pre-mix into a bag of flour as it's packaged, or adding fortified rice grains into a bag of rice.

Additional reading:

• Part One
• Part Two
• Part Three

Guidelines on food fortification (University of California, Davis)