It must be remembered that the body is not nourished merely by swallowing food: in order to nourish the body food must also be digested, absorbed, and made use of by the tissues. Many factors may operate both in health and in sickness to render food indigestible. It may be originally unsuited to the human digestive apparatus, or spoiled, or poor in quality, or badly cooked. But even when wholesome in itself it may be ill-adapted to a particular person at a particular time; thus it may be too great in amount, or eaten at improper hours. Moreover a person's own idiosyncrasy or manner of living or fatigue or illness may render it especially indigestible for him.
Experiments have shown that pain, fear, worry, and other unpleasant emotions actually stop the action of the digestive juices and check muscular contractions of the small intestine. Furthermore, even the absence of pleasant anticipation of food has been shown to delay digestion for hours. Thus scientific knowledge confirms our common experience that such mental states seriously interfere with digestion. The converse is also
true. Agreeable taste and odor of food, or even pleasurable thought of it, start the secretion of digestive fluids. It is a common saying that the mouth waters at the prospect of inviting food, but it is less well known that appetizing food does actually start the stomach juices also. A person who understands the physiological effect that the emotions have upon digestion is in a far better frame of mind to cope successfully with the difficulties of feeding the sick than one who considers sick persons' likes and dislikes entirely irrational.
FEEDING THE SICK
Nourishing the sick is not always an easy problem, but its importance can hardly be overestimated. Indeed, proper feeding in many illnesses makes the difference between life and death. The actual amount of nourishment needed in sickness is often less than in health, but it may be just as great, or even greater if the illness causes increased tissue waste. Yet the digestive process of a sick person must be rendered as little laborious as possible, all foods ordinarily difficult to digest must be eliminated, certain others must be withheld or restricted according to the nature of the sickness, and in addition one may have to deal with an appetite that is capricious, diminished, or totally absent.
Diet for the sick is often a part of medical treatment; in such cases the doctor will prescribe special diets and his orders must be carefully carried out. Except for special diets, food for the sick is generally divided into four classes: first, liquid or fluid diet; second, semi-solid diet; third, light or convalescent diet; and lastly, full diet. These diets are not very sharply distinguished.
Liquid diet
generally includes milk, eggnog, albumen water, broths, soup, beef juice, thin gruel, and beverages. Liquid diet makes least demand upon the digestive powers, because it consists of food already dissolved and therefore nearer the condition in which it can be absorbed. Moreover, it is less likely than other foods to contain excess of fat, improperly cooked starches, and other indigestible material. Liquids must be given at regular intervals and at shorter intervals than solid foods; 6 to 8 ounces every two or three hours is not too much if the patient can take it. The doctor usually specifies the amount and the interval. Some patients will take more nourishment at one time if the interval is slightly increased.
Semi-solid diet
includes all fluids and in addition soft milk toast, soft cooked eggs, well cooked cereal, custards, ice cream and ices, junket, and gelatine jellies. Liquid or semi-solid diet is commonly given in acute fevers because digestive