While glucose is wholesome, it ferments readily.
Before sugar can be used by the system, it is changed into the easily absorbed form of the sugar in grapes, by a ferment in the small intestine. Hence digested sugar in the body is called grape sugar.
Milk sugar needs less chemical change than other sugars and is taken almost at once into the circulation. It is contained in the natural food for the infant.
The digested sugar (grape sugar) is further changed in the body into glycogen. When an excess of sugar or starch is consumed, it is stored within the body as glycogen, until required.
Sugar is perhaps a better food than starch, because less force is required for its digestion and it is easily assimilated, being more readily converted into dextrose than are starches.[3] Moreover it furnishes the heat and energy needed by those having small power to digest starch.
Sugar is soon oxidized, and, for this reason may be eaten by those who need to use an extra amount of muscular strength, or to get strength quickly. It yields heat and energy within thirty minutes after eating, and in times of great exertion or exhausting labor, the rapidity with which it is assimilated gives it advantage over starch. Because it is so quickly converted into energy it is valuable for children at active play.
Experiments with soldiers on forced marches, and in Arctic explorations, have shown the value of sugar as a food, in enabling the men to withstand hunger, thirst, and fatigue. Taken in excess, however, particularly by those of sedentary habits, it clogs the system as does any other excess of material, creating difficulties for the liver and kidneys.
During muscular activity, four times as much sugar is consumed in the body as is ordinarily used in the body processes.
Used in limited quantities, therefore, according to the muscular or brain power exercised, sugar is one of the best foods for the production of energy.
When much sugar is eaten the starches and fats in the food should be lessened to avoid overloading the system.