Heme iron is significantly more bioavailable than non-heme iron because it is encased in a porphyrin ring.

“now it's important to know that heme iron is iron an atom of iron encased in a porphyrin ring that is the kind of iron you find in animal Foods it is much more bioavailable something I talk about a lot than iron found in plant foods which is non-heem iron so hemoglobin is a large molecule composed of four protein subunits including porphyrin ring and iron and that is why heme iron is much more easily incorporated into red blood cells into hemoglobin into the oxygen carrying Machinery of the human body”