Why Your Stomach Doesn't Digest Itself

Your stomach makes acid strong enough to corrode metal. So why doesn't it digest itself?

The acid inside your stomach can dissolve a razor blade. Your stomach lining is just soft, living tissue. So what stops it from being eaten alive?

Three defenses work together. First, special cells coat the wall in a thick layer of mucus loaded with bicarbonate, a natural antacid that neutralizes acid right at the surface. Second, the cells of the lining are sealed together so tightly that acid cannot slip between them. And third, the lining simply does not last long enough to be damaged. Your entire stomach surface is rebuilt every few days, shedding worn cells before the acid can break through.

So your stomach survives by constant replacement. You essentially grow a brand new lining every three to five days. When that defense fails, the acid wins, and you get an ulcer.

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