Acid can corrode even an iron nail—so why didn’t it digest your stomach?
Let’s start with how powerful it is: stomach acid is real hydrochloric acid, with a pH of 1.5 to 3.5—on par with toilet bowl cleaner. So if you soak an iron nail for a few days, its surface will be chewed away into pits.
With such a harsh liquid constantly swirling around inside your belly, why doesn’t the stomach get messed up? It relies on a three-layer protective design.
The first layer is the mucus layer that coats the stomach lining. It’s packed with bicarbonate (hydrogen carbonate), essentially built-in, slow-release baking soda: in the stomach lumen the pH is about 2, but when it reaches the surface of the epithelium it rises to nearly neutral—around 6 to 7.
The second layer is rapid replacement. The stomach’s epithelial cells renew the entire layer every 3 to 5 days, so any corrosion is promptly patched up.
The third layer is energy supply from the bloodstream—ready for repairs at any time. Once this defense line is breached, trouble starts: Helicobacter pylori burrows into the mucus layer and moves in, or painkillers like aspirin reduce protective mucus secretion, and the stomach begins digesting itself—meaning ulcers. In 1982, an Australian doctor, Dr. Marshall, directly drank a cup of H. pylori to prove the link. This discovery earned the 2005 Nobel Prize.
Your stomach actually spends every day standing on the edge of a cliff. Before you binge eat next time, think about how hard it works.
Let’s start with how powerful it is: stomach acid is real hydrochloric acid, with a pH of 1.5 to 3.5—on par with toilet bowl cleaner. So if you soak an iron nail for a few days, its surface will be chewed away into pits.
With such a harsh liquid constantly swirling around inside your belly, why doesn’t the stomach get messed up? It relies on a three-layer protective design.
The first layer is the mucus layer that coats the stomach lining. It’s packed with bicarbonate (hydrogen carbonate), essentially built-in, slow-release baking soda: in the stomach lumen the pH is about 2, but when it reaches the surface of the epithelium it rises to nearly neutral—around 6 to 7.
The second layer is rapid replacement. The stomach’s epithelial cells renew the entire layer every 3 to 5 days, so any corrosion is promptly patched up.
The third layer is energy supply from the bloodstream—ready for repairs at any time. Once this defense line is breached, trouble starts: Helicobacter pylori burrows into the mucus layer and moves in, or painkillers like aspirin reduce protective mucus secretion, and the stomach begins digesting itself—meaning ulcers. In 1982, an Australian doctor, Dr. Marshall, directly drank a cup of H. pylori to prove the link. This discovery earned the 2005 Nobel Prize.
Your stomach actually spends every day standing on the edge of a cliff. Before you binge eat next time, think about how hard it works.
