Proprietary foods are sometimes ordered with a view to increasing the quantity of some particular primary food-stuff in the diet, whether protein, fat, or carbo-hydrate. Yet there are ordinary articles of diet, almost universally available, which will provide all that is needed.

Assuming that an extra amount of protein food is required, it can be given in the form of white of egg, dried meat powder, or junket made from skimmed milk. The egg and junket are purin-free foods. Meat powders can be bought with advantage in the form of a proprietary food. The extra cost is outweighed, perhaps, by the trouble involved in making such a food at home. So, too, milk proteins can be obtained, in a purer form than junket, from the makers of the various preparations of dried milk casein. As a general rule it is unnecessary to increase the amount of protein in the diet beyond what is being taken in the ordinary diet. Three pints of milk will supply enough protein for most people when in bed. Occasionally meat powders or dried milk foods are useful additions to the diet of patients who can only take liquid or semi-solid foods, as in the case of oesophageal obstruction. Fats are available in the form of pure olive oil, butter (80 per cent fat), margarine, dripping and cream. Mutton fat is less easily digested and absorbed than other fats, especially when hot, more passing out in the stools.

Extra carbo-hydrates can be given in the form of cane sugar, milk sugar, honey, treacle or golden syrup, and maple syrup. Barley sugar and sugar candy are practically pure preparations of sugar. Toffee, too, is a valuable sweet, being a mixture of butter and sugar, the latter considerably inverted in cooking and rendered more apt for digestion.

The Composition Of Honey

Water......... 13-16

Invert Sugar....... 74-78

Cane Sugar ........ 2.69

Protein........ 130

Mineral ash. . . . . . . 0.12

Malt extract contains from 60 to 70 per cent of carbohydrates, of which about three-fourths is sugar. It costs four times as much as honey and its calorific value is less.

Proprietary foods may be classified as follows: -

1. Prepared From Cows' Milk

A. Condensed milk, without added sugar.

B. Condensed milk, with added sugar.

C. Dried milk preparations.

D. Predigested milk.

E. Modified milk.

II. Cows' Milk With Carbo-Hydrate (Cereal) Additions

A. The starch practically unchanged.

B. The starch partly or entirely converted into soluble carbo-hydrates, viz. dextrins, maltose and dextrose.

C. The milk partially digested, or the food contains ferments which partially or entirely convert the protein and starch during preparation.

III. Carbo-Hydrate Foods

A. Starch, practically unchanged.

B. Starch, partially changed into soluble carbo-hydrates.

C. Starch, completely changed.

D. Malt extracts.

IV. Nitrogenous Foods

(1) From meat.

A. Meat Teas.

B. Meat Extracts.

C. Meat Juices.

D. Peptone Preparations.

E. Meat Powders.

(2) From fish.

(3) From vegetable foods.

(4) From vegetable and animal substances.

V. Fatty foods.

VI. Combination Foods

A. Fat and protein.

B. Fat and carbo-hydrate.

C. Fat, protein and carbo-hydrate.

The composition of the different foods is given in the following tables arranged in alphabetical order, for the purpose of reference. The analyses are those deemed most reliable, but must not be taken as being absolutely accurate.