Do the bacteria in my stomach stop food borne illness?

Acid Actions: While there are bacteria that reside in our stomach, it is actually the acid environment and thick mucous layer that protect us from bacterial invasion in bad foods. Unfortunately, most food borne illness are from pre-formed toxins made by the bacteria in the food before we've eaten it. The toxins are often less likely to be affected by the acid and as a result we get ill following consumption.