Definition & Meaning of "cast-iron stomach"

What is the origin of the idiom "cast-iron stomach" and when to use it?

The idiom "cast-iron stomach" originates from the idea that someone's stomach is exceptionally strong and resilient, similar to cast iron, which is known for its durability and ability to withstand high heat. This phrase is used to describe a person who can consume or digest a wide range of foods without getting sick or experiencing digestive issues.