Final answer:
Vegetarians need twice as much iron to make up for the low bioavailability of iron in their diet.
Step-by-step explanation:
Vegetarians need twice as much iron to make up for the low bioavailability of iron in their diet. This is because iron from plant sources is not as easily absorbed by the body compared to iron from animal sources. So, vegetarians need to consume a larger amount of iron in their diet to ensure they are meeting their body's iron requirements.