I’ve recently watched a video in which someone used a magnet to collect metalic iron particles in a bag of cheerios. He then claimed that you actually absorb very little of this iron because our body only absorbs iron in ionic form, and only a small part of the metalic form gets converted into ionic. To what extant is this true? I rarely eat red meat and a very lrage part of my iron intake comes from fortifiedcereals, so ik a little concered.
It’s pretty accurate. Essentially, this is the difference between heme (elemental) and non-heme (ionized) iron.
Non-heme iron isn’t the most effectively absorbed; however, consuming alongside vitamin C will help increase absorption.
One downside of focusing iron intake in the form of fortified cereals is that calcium (like from milk) competes with iron for absorption.
Heme iron is much more easily absorbed, but is most often found in animal products - especially meat. While red meat is a good source of heme iron, all animal meats contain it. So if you eat poultry, pork, fish, etc., you’re getting heme iron in your diet.
Other non-heme sources include things like spinach, most legumes, and other seeds/nuts. For most (if not all) non-heme sources, cooking will improve bioavailability of iron, making more of it potentially absorbable.