This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Grape sugar and fruit sugar or levulose, when eaten in large quantity in health, reappear unaltered in the urine, but the latter sugar in diabetes is said by Moritz to be consumed within the body. Sugar eaten in excess with other food increases the quantity of urine and feces and the urea elimination (W. G. Morgan).
Saccharose, eaten in excess, may reappear in the urine unaltered, or more commonly as glucose.
Lactose is converted into glucose, and it produces functional glycosuria more easily than the latter if eaten in bulk.
Alimentary glycosuria usually ceases in a few hours after discontinuance of eating the food which has caused it.
There are some diseases in which sugar in all forms should be strictly avoided, such as flatulent dyspepsia, acute and chronic gastritis, gastric dilatation, gout, rheumatism, obesity, and the uric-acid diathesis, and it should be absolutely forbidden in diabetes. Temporary disturbances of digestion from eating too much sweet food are very common, and can usually be rectified by simple remedies, and by withholding or diminishing the customary allowance of sugar. Sugar eaten constantly in excess spoils the teeth and destroys the appetite for other food. It lessens the hydrochloric acid of the gastric juice in cases of hyperchlorhydria, and is said to dissolve mucus.
Cane sugar, saccharose, or sucrose, as used in the United States, is usually derived from the clarified and crystallised juices of the sugar cane (saccharum offcinarum), but it is also made from beet root, as originally discovered by Marggraf, of Berlin, in 1747. The latter form is somewhat less sweet than are the better grades of cane sugar. The root contains 12 to 15 per cent of sugar. One third the world's commercial sugar is derived from sugar cane, and two thirds from beets. The annual per capita consumption of sugar in the United States is 66 pounds. About one quarter of a pound per diem may be eaten without harm. Much more than this in a short time is liable to disorder digestion, just as do the equally diffusible peptones eaten in excess.
Mary Hinman Abel, in an exhaustive study of the food value of sugar, says:
"There is no proof that sugar is harmful to the teeth, although doubtless sweet food, allowed to cling to the teeth after eating, rapidly ferments, and acids will be formed that, according to Professor Miller, of Berlin, may attack the teeth. This is equally true of starchy foods. It is said, however, that the negroes of the West Indies, who consume enormous quantities of sugar, have the finest teeth in the world. It is also unproved that sugar produces gout".
Sugar is better digested in proportion to the amount of exercise taken.
The maple tree yields from 2 to 10 per cent of sucrose. Maple sugar is eaten chiefly as a luxury, on account of its unique and agreeable flavour. It also makes an excellent sirup which is in great demand. About 7,500,000 pounds of maple sugar are made annually in the United States. Cane sugar can be obtained from the sugar pea, from the flower buds of the coca palm, and from other substances. It is soluble in half its weight of cold water and in less hot water.
The sap which is drawn from the sugar cane as well as the juice of compressed beet root is not a pure aqueous solution of sugar, but is mingled with other materials, chiefly of a mucilaginous character. An elaborate process of refining is applied in order to produce the commercial white sugars of various grades. The principal steps in this process are as follows: "1, Melting of the sugar; 2, straining through bag filters; 3, filtering through charcoal; 4, boiling or evaporating the decolourised liquid in vacuum pans; 5, separation of crystallised sugar by centrifugals " (Clark). The process is so cheap that cane sugar is practically never adulterated.
Cane sugar was formerly sold more extensively than at present in the form of coarse brown sugar. This variety is somewhat impure, and on this account has a slightly laxative action; but the great improvements made of late years in the processes of refining sugar, and the extreme cheapness of this commodity, place the clarified forms of it within the reach of all, and even reduce to a minimum the temptation for sophistication which was originally much more extensively practised, especially in the adulteration of confectionery, with chalk, plaster of Paris, etc.
The most highly refined cane sugars contain about 0.25 per cent only of impurities and ash, but poorer grades hold 1 to 2.3 per cent, with as much water (König). Cane sugar is about two and a half times sweeter than glucose. Cane sugar is completely digested and absorbed, leaving no fecal residue.
"Grocer's itch" is a form of irritation of the skin of the hands sometimes acquired from contact with moist brown sugar, adulterated with dirt or sand and mites.