That is a great question! It is great because you have thought about it like a real scientist. You have taken two ideas, seen the link and come up with a new idea, briliant.
Iron is magnetic but we do not have enough in our blood to make us magnetic. However, I will tell you one of my favourite scientific facts. Water is very slightly magnetic. If you expose water to a very very strong magnet it will become magnetic. We can do this to levitate things filled with water!
@michellerana Good question! I don’t know the answer, BUT I do know that a weak magnetic field can be induced within the body by an external magnetic source, as this technique is used safely by hospitals to do magnetic resonance imaging (MRI) scans. I had to have one when my back was hurting and the doctors didn’t know what was wrong. The MRI scan showed that I had damaged 3 of the discs in my back.
This is a brilliant question!! Just like philippa said the water in our body is very useful to use for MRI scanning as it can be slightly changed by a magnetic pulse. Somebody in my lab is using this technique to look at the brain of a rat right after it has had a stroke. This is a very interesting area of stroke research as it can be directly related to what we can see in human patients in hospital MRI scanners soon after they have had a stroke. As animal researchers we are constantly trying to make direct comparisons to what you see in patients.