Final answer:
Substances such as vitamin C, protein, and citric acid enhance non-heme iron absorption, while substances such as calcium, tea, and coffee can inhibit it.
Step-by-step explanation:
Iron absorption is enhanced by substances such as vitamin C, protein, and citric acid. These substances help in the formation of soluble iron chelates, which aid in the absorption of non-heme iron. On the other hand, substances such as calcium, tea, and coffee can inhibit non-heme iron absorption.