It has been taught until recently by all dietists that Starches as food elements exclusively supply bodily warmth, and fat; but now the discovery equally of force-production from assimilated Starches, as, for instance, largely in white bread, or in potatoes, leads to a knowledge in signal advance of previous notions, whilst supported by modern experience. And therefore the conclusion is warranted that the bodily energies may be maintained in their full vigour by starchy vegetable nourishment quite as well as by the more stimulating, (and more expensive) animal foods. The conversion of Starches into available nutriment takes place mainly by their combination with saliva in the mouth; but this saliva does not act upon raw Starch, therefore it must be first made soluble by cookery; if through dry heat by becoming changed into soluble dextrin, which is a gummy substance familiar to everyone as the sticky material on the back of postage stamps. Similarly the crust of a loaf of bread consists chiefly of Starch which has been converted by the dry heat of the oven into soluble Starch, and dextrin.

The carbohydrates of flour, or meal, are present mainly in the form of insoluble Starch, which must undergo conversion into soluble Starch, dextrin, maltose, and dextrose, before it can be assimilated as useful sustenance. This change is effected, or should be, chiefly by the saliva in the mouth, and is then continued in the stomach. The process of baking changes the Starch to a state of jelly, or mucilage, which in the crust is further baked brown, and hard. When we consider how large a part of our daily food consists of bread, and of vegetable Starches, the importance of our exceptional salivary power, and the necessity for keeping its secreting organs healthy, are at once evident; other products being also formed besides the soluble dextrin, viz., maltose, and dextrose, which are fermentable sugars. Dextrin when it reaches the stomach becomes glucose, as likewise in the sweet- (stomach-) bread, leading on therefrom to the intestines. By contrast, cane sugar, when eaten, becomes sucrose in the stomach, and intestines. The glucose has to be stored in the liver; but if that organ is at fault the glucose is detained in the blood, and in other fluids of the body, causing diabetes.

Otherwise the glucose serves for use throughout the body as required for supplying warmth, and vital energy.

Starch forms the greatest part of all farinaceous substances, particularly of wheat flour. But carnivorous animals living exclusively upon flesh are found also to acquire glycogen within their bodies, which substance therefore cannot be altogether restricted to Starches as its source; and for this reason it becomes debatable whether diabetic patients are sugarless even on a restricted animal diet. Some of the patent foods, which are largely advertised as being predigested artificially, so that the Starch is already converted into nourishing substance without taxing the saliva, or the stomach-bread, are nevertheless severally deficient in fat, and still containing some unchanged Starch; (with the single exception, says Dr. Hutchison, of Mellin's Food for Infants, which is quite free from unconverted Starch). In the treatment of diabetes it is no longer considered wise, or necessary, to absolutely prohibit all Starches from the diet, else a worse condition supervenes, known as acetonuria, with a great risk of blood-poisoning, heavy unconsciousness, and death.

It is true that proteids, and fat, will in a measure serve to take the place of the Starches, the latter being a compact source of energy; but these substitutes must put the liver to task, which is already inefficient as to its function of sugar conversion. Proteids are able to produce a certain moderate amount of sugar.

The best sources of fat are butter (quite fresh), bacon, pork, and fatty fish, (as eels, salmon, mackerel, herrings, sprats, sardines in oil), suet dripping, salad oil, yolk of eggs, and thick cream. In milder cases of diabetes some potatoes may be permitted (as explained here in "Potato," page 579), and may be made into a puree with butter, or cream. A given quantity of Potatoes, cooked in their jackets, by steam, and mashed, should readily take up half their weight of butter, or a quarter of their weight of thick cream. Fat may be likewise given in more severe cases with mashed greens, cooked in little, or no water except their own juices, or that of an added lettuce. Eggs, too, can be scrambled with plenty of butter; and clarified butter may be served with fish, or with asparagus, etc. It is worth remembering that the use of alcohol, if otherwise proper, at meals greatly aids the digestion of fat. Green vegetables may be freely allowed.

In the sixteenth and seventeenth centuries, the Starch used in laundries for stiffening ruffs, collars, etc., was frequently coloured yellow, this being at one time extremely fashionable; but blue Starch was affected by the Puritans. Addison, in the Spectator (305), talks of "a Professor who is to give a certain society their ' stiffening,' and to infuse into their manners that beneficial political Starch which may qualify them for levees, conferences, visits, etc." Formerly, in this country, before tea and coffee were introduced, a restorative starchy drink known as Salep was prepared from the roots of the common male Orchis. It was held in high repute for recruiting the exhausted vitality of aged, and enfeebled persons; and it may still be prepared from a powder as supplied by the druggist, which is to be boiled in water with some spirit added. This differs from Saloop (page 565), also a former restorative drink, (made famous by Elia,) the ground-work of which was Sassafras wood.