Eli5 Why does saliva taste like blood when you exhaust yourself?

Question

Why does your saliva start to taste like blood if you ride your bike up a hill or run fast for a while?

Edit: Thanks for the Awards and the nice Comments.
Also blew up bigger than I thought!

In: Biology

Answer 1

**Eli5 version**: Our blood contains iron. When you do strenuous exercise the pipes supplying blood to the balloons in your chest start leaking some of that iron-containing part of blood. When the balloons deflate, that’s when you exhale, some of that iron reaches your mouth from those balloons and your taste-thingamagigs tell you that you have iron in your mouth.