So long as the body is normal, the digestive secretions are sufficient protection against the fermentation and putrefaction of food, which would otherwise be set up by microbes. If, however, the vital powers are lowered so that the secretions are deficient in quality or are insufficient in quantity, or, if there is disease, which impairs the digestive powers, bacterial fermentation sets in and we have indigestion. The fermentation produces toxins of various kinds, which, when absorbed into the blood and lymph, serve to poison the body. Some of these poisons are the ptomains and leucomains; phenol, cresol, leucin, tryson, ammonia, sulphurated hydrogen, fatty acids, oxalic and uric acids, alcohol and the xanthin bodies. Of these, indol is the most easily absorbed and is most readily recognized in the urine.
The chief causes of gastro-intestinal indigestion are overeating, enervation and bad food combinations. Enervating influences are anything that lowers nerve force and include such things as overwork, underwork, extremes of cold and heat, use of stimulants, sexual excesses, etc. Anything that enervates lessens digestive power and becomes an indirect cause of indigestion.
Overeating overworks the digestive organs, as well as introduces more food into the system than is needed. Food eaten in excess is bound to accumulate as waste and decompose as poison.
Other things being equal, digestion is more efficient when but one food is eaten. A single article of food will digest more quickly and perfectly than will the same food if mixed with other foods. The more foods one takes together, the less efficient is the process of digestion.
From the differences in the results of fermentation and those of digestion, it should be apparent that, although, the enzymes are spoken of as ferments, they do not produce fermentation. Rather, the digestive juices and their enzymes act as powerful solvents--for (and keep this fact in mind), digestion reduces food-stuffs to the diffusible state without depriving them of their organic qualities, while fermentation renders them diffusible by reducing them to the inorganic and, therefore, useless state. Digestion is solution; fermentation is disintegration.