Foods contain ‘ash’, which depending on its mineral contents may be acid-forming or base-forming, having an impact on the acid-base balance in the body.
Ash is the total amount of inorganic material (minerals) left after organic material and water has been removed from food by a breakdown in the body’s digestive system (or in the laboratory environment). In other words, it is the particles left after burning all organic material and removing water. The ash content of food is normally below 5%. However, some products such as dry meats may contain more.
Ions are atoms or groups of atoms with a different number of electrons and protons.
If ash contains more positive ions called cations, it is called base-ash (or alkaline-ash) and is base-forming (alkaline). Cations have more protons. Examples of some more common base–ash particles: potassium, sodium, calcium and magnesium.
If ash contains more negative ions called anions, it is called acid-ash and is acid-forming. Anions have more electrons. Some examples of more common acid-ash particles are: phosphate, chlorine and sulfur. (1, 2, 3)