The stomach produces hydrochloric acid (HCl) with a very low pH. It's so powerful that it can melt metal! To keep from digesting itself, your stomach creates a thick layer of mucus and replaces its entire lining every few days.
Inside your belly is a pool of liquid so corrosive that it could burn a hole through wood or dissolve a piece of steel. This is Hydrochloric Acid (HCl), and it is the primary tool your body uses to break down food.
Scientists measure acidity using the pH scale (from 0 to 14).
In a famous study, researchers found that after 24 hours in stomach acid, a single-edged razor blade lost about 17% of its mass and became incredibly thin and brittle. (Note: Please do not try eating metal to test this!)
If the acid is that strong, why doesn't it melt us from the inside out? Your stomach uses a brilliant defense system: it secretes a thick, gooey bicarbonate-rich mucus that coats the stomach walls. This mucus acts as a chemical buffer. Furthermore, the cells lining your stomach grow so fast that you get a completely new stomach lining roughly every 3 to 4 days.
Your stomach is a living chemistry lab. It produces one of the most aggressive substances in nature but stays safe by constantly rebuilding itself. It's a perfect example of how the human body balances power with protection.