Stomach acid of humans

I'm not sure where pH of 4-5 with food came from for humans, but it varies with every animal that dumps contents into a sack through the mouth.

For example, http://faculty.stcc.edu/AandP/AP/AP2pages/Units24to26/digestion/control.htm


Check out the gastric phase.

Human chyme is approximately at a pH of 2 as it moves out of the stomach, pH almost always increases with food or other contents altering the environment as they enter.

Another link, http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDIGEST.html


Mentions hydrochloric acid of pH 1.5 to 2.5 in the human stomach.

Point is, stomach acid lowers to digests foods depending on what the food may be, ie. pepsin for protein digestion. Pepsin is secreted and active only at pH of around 2. Tweet