Many iron fortified cereals contain tiny iron fillings. I’m talking about plain old elemental iron, the kind you would find in a nail, train or car, in your breakfast cereal. It turns out that this form of iron is ideal for a cereal additive.

The reason is that iron ions (iron that would more easily combine with other molecules in the cereal) increase the spoilage rate of the food. Using iron in its pure metal form gives the cereal a longer shelf-life. Of course, not all cereals use elemental iron, some use iron in the form of ferrous sulfate (FeSO).

For those that use elemental iron, after ingestion, the hydrochloric acid and other chemicals in your stomach react with the iron to form FeCl, a compound easily absorbed through the intestines. Generally however, much of the iron remains untouched and is excreted.

The most important roles of iron in the body are in oxygen transport and electron transfer in respiration. Iron binds oxygen in the blood, allowing an adequate supply of oxygen to be carried throughout the body from the lungs. Iron is also involved in immune reactions of the body. If the body does not receive an adequate supply of iron, red blood cells in the body are not as effective at transporting oxygen.

Check out how much iron is inside various cereals (and other foods) at the Nutrition Data website.

Do this at home

If you want to try this experiment at home or in your classroom you will need a few things.

  • Various cereals that are iron fortified
  • A large ziplock bag
  • Some water
  • A very strong magnet

The critical item you need for this experiment is a very strong magnet. A regular refrigerator magnet will not be strong enough to pull the iron out of the cereal and water mixture. Check out the following sites for magnets strong enough for this experiment.

Once you have your magnet your are all set. Grab a cup or two of cereal and place it in a bowl. Crush the cereal into as fine a powder as you can. Take this fine powder and add two or three cups of water inside a ziplock bag. Allow the cereal and water to soak for 20 minutes or so and then bring the magnet near the bottom of the bag. Since the iron is heavier than the cereal/water mixture you will have more success gathering iron near the bottom of the bag. Move your magnet around for a few minutes and then carefully slide it to the top of the bag. You should see a small black spot of iron that you can move around with the magnet.