1 · The heme that was not absorbed keeps going
Unabsorbed heme iron travels with the food residue into the colon, the starting point of a leading mechanistic hypothesis for the link between red meat and colorectal cancer.Heme iron's absorption is high among food irons, but high does not mean all of it. What does not enter the wall cell travels on with the residue into the colon — the only place that soaks in residue for a long time.First, the kind of evidence: the chain below is a leading mechanistic hypothesis for the link between red meat and colorectal cancer, and its evidence comes mostly from animal and laboratory studies. It helps explain the association seen in populations, but it does not prove that this is what causally happens in people.