THE DIGESTION OF FOODS

" Liver Digestion. — The liver as well as the stomach is a digestive organ, and in a double sense. It not only secretes a digestive fluid, the bile, but it acts upon the food brought to it by the portal vein, and regulates the supply of digested food to the general system. It converts a large share of the grape- sugar and partially digested starch brought to it into a kind of liver starch, termed glycogen, which it stores up in its tissues. During the interval between the meals, the liver gradually re- digests the glycogen, reconverting it into sugar, and thus sup- plying it to the blood in small quantities, instead of allowing the entire amount formed in digestion to enter the circulation at once. If too large an amount of sugar entered the system at once, it would be unable to use it all, and would be compelled to get rid of a considerable portion through the kidneys. The liver also completes the digestion of albumen and other food elements."

Time Required for Digestion. — The length of time re- quired for stomach digestion varies with different food sub- stances. The following table shows the time necessary for the stomach digestion of some of the more commonly used foods : —

Beans, pod, boiled. . . .

Bread, wheaten

Bread, corn

Apples, sour and raw. Apples, sweet and raw

Parsnips, boiled

Beets, boiled

Turnips, flat, boiled . . Potatoes, Irish, boiled. Potatoes, Irish, baked.

Cabbage, raw

Cabbage, boiled

Milk, boiled

Milk, raw

Eggs, hard boiled ....

Eggs, soft boiled

Eggs, fried

Eggs, raw

hrs. min.

Eggs, whipped i 30

Salmon, salted, boiled 4 00

Oysters, raw 2 55

Oysters, stewed 3 30

Beef, lean, rare roasted 3 00

Beefsteak, boiled 3 00

Beef, lean, fried 4 00

Beef, salted, boiled 4 15

Pork, roasted 5 15

Pork, salted, fried 4 15

Mutton, roasted 3 15

Mutton, broiled 3 00

Veal, broiled 4 00

Veal, fried 4 30

Fowls, boiled 4 00

Duck, roasted 4 30

Butter, melted 3 30

Cheese 3 30

Soup, marrowbone 4 '5

Soup, bean 3 00

Soup, mutton 3 3°

Chicken, boiled . . . .^ 3 00

40 SCIENCE IN THE KITCHEN.

The time required for the digestion of food also depends upon the condition under which the food is eaten. Healthy stomach digestion requires at least five hours for its completion, and the stomach should have an hour for rest before another meal. If fresh food is taken before that which preceded it is digested, the portion of food remaining in the stomach is likely to undergo fermentation, thus rendering the whole mass of food unfit for the nutrition of the body, besides fostering various dis- turbances of digestion. It has been shown by recent observa- tions that the length of time required for food to pass through the entire digestive process to which it is subjected in the mouth, stomach, and small intestines, is from twelve to four- teen hours.

Hygiene of Digestion.— With the stomach and other di- gestive organs in a state of perfect health, one is entirely un- conscious of their existence, save when a feeling of hunger calls attention to the fact that food is required, or satiety warns us that a sufficient amount or too much has been eaten. Perfect digestion can only be maintained by careful observance of the rules of health in regard to habits of eating.

On the subject of Hygiene of Digestion we again quote a few paragraphs from Dr. Kellogg's work on Physiolog}', in which is given a concise summary of the more important points relating to this : —

" The hygiene of digestion has to do with the quality and quantity of food eaten, and the manner of eating it.

" Hasty Eating. — If the food is eaten too rapidly, it will not be properly divided, and when swallowed in coarse lumps, the digestive fluids cannot readily act upon it. On account of the insufficient mastication, the saliva will be deficient in quantity, and, as a consequence, the starch will not be well digested, and the stomach will not secrete a sufficient amount of gastric juice. It is not well to eat only soft or liquid food, as we are likely to swallow it without proper chewing. A considerable proportion of hard food, which requires thorough mastication, should be eaten at every meal.

TIIK DKJESTION OF FOODS. 41

'' Dri)iki)tg- Freely at Meals is harmful, as it not only encour- ages hasty eating, but dilutes the gastric juice, and thus lessens its activity. The food should be chewed until sufficiently moistened by saliva to allow it to be swallowed. When large quantities of fluid are taken into the stomach, digestion does not begin until a considerable portion of the fluid has been absorbed. If cold foods or drinks are taken with the meal, such as ice-cream, ice-water, iceid milk or tea, the stomach is chilled, and a long delay in the digestive process is occa- sioned.

" The Indians of Brazil carefully abstain from drinking when eating, and the same custom prevails among many other savage tribes.

'^Rating betzveeii Meals. — The habit of eating apples, nuts, fruits, confectionary, etc., between meals is exceedingly harm- ful, and certain to produce loss of appetite and indigestion. The stomach as well as the muscles and other organs of the body requires rest. The frequency with which meals should be taken depends somewhat upon the age and occupation of an individual. Infants take their food at short intervals, and, ow- ing to its simple character, are able to digest it very quickly. Adults should not take food oftener than three times a dai)' ; and persons whose employment is sedentary may, in many cases at least, adopt with advantage the plan of the ancient Greeks, who ate but twice a day. The latter custom is quite general among the higher classes in France and Spain, and in several South American countries.

" Simplicity in Diet. — Taking too many kinds of food at a meal is a common fault which is often a cause of disease of the digestive organs. Those nations are the most hard}' and enduring whose dietary is most simple. The Scotch peasantry live chiefly upon oatmeal, the Irish upon potatoes, milk, and oatmeal, the Italian upon peas, beans, macaroni, and chestnuts ; yet all these are noted for remarkable health and endurance. The natives of the Canary Islands, an exceedingly well-developed and vigorous race, subsist almost chiefly upon

42 SCIENCE IN THE KITCHEN.

a food which they call gofio, consisting of parched grain, coarsely ground in a mortar and mixed with water.

"'Eating when Tired. — It is not well to eat when exhausted by violent exercise, as the system is not prepared to do the work of digestion well. Sleeping immediately after eating is also a harmful practice. The process of digestion cannot well be performed during sleep, and sleep is disturbed by the ineffec- tive efforts of the digestive organs. Hence the well-known evil effects of late suppers.

''Eating too Much. — Hasty eating is the greatest cause of over-eating. When one eats too rapidly, the food is crowded into the stomach so fast that nature has no time to cry, ' Enough,' by taking away the appetite before too much has been eaten. When an excess of food is taken, it is likely to ferment or sour before it can be digested. One Avho eats too much usually feels dull after eating.

'' Hoiv Mucli Food is En&ngh ? —^ThQ proper quantity for each person to take is what he is able to digest and utilize. This amount varies with each individual, at different times. The amount needed will vary with the amount of work done, mental or muscular ; with the weather or the season of the year, more food being required in cold than in warm weather : with the age of an individual, very old and very young per- sons requiring less food than those of middle age. An unper- verted appetite, not artificially stimulated, is a safe guide. Drowsiness, dullness, and heaviness at the stomach are indica- tions of an excess of eating, and naturally suggest a lessening of the quantity of food, unless the symptoms are known to arise from some other cause.

" Excess of Certain Food Elements. — When sugar is too freely used, either with food or in the form of sweetmeats or candies, indigestion, and even more serious disease, is likely to result. Fats, when freely used, give rise to indigestion and ' biliousness.' An excess of albumen from the too free use of meat is harmful. Only a limited amount of this element can be used ; an excess is treated as waste matter, and must be re- moved from the system by the liver and the kidneys. The

THE DIGESTION OF FOODS. 43

majority of persons would enjoy better health by using meat more moderately than is customary in this country.

'^Deficiency of Certain Food Elements. — A diet deficient in any important food element is even more detrimental to health than a diet in which certain elements are in excess.

"The popular notion that beef-tea and meat extracts con- tain the nourishing- elements of meat in a concentrated form, is a dangerous error. Undoubtedly many sick persons have been starved by being fed exclusively upon these articles, which are almost wholly composed of waste substances. Prof. Paule Bernard, of Paris, found that dogs fed upon meat extracts died sooner than those which received only water."

Food=Combinations. — Some persons, especially those of weak digestive powers, often experience inconvenience in the use of certain foods, owing to their improper combinations with other articles. Many foods which are digested easily when partaken of alone or in harmonious combinations, create much disturbance when eaten at the same meal with several different articles of food, or with some particular article with which they are especially incompatible. The following food combinations are among the best, the relative excellence of each being in- dicated by the order in which they are named : Milk and grains ; grains and eggs ; grains and vegetables or meats ; grains and fruits.

Persons with sound stomachs and vigorous digestion will seldom experience inconvenience in making use of other and more varied combinations, but dyspeptics and persons troubled with slow digestion will find it to their advantage to select from the bill of fare such articles as best accord with each other, and to avoid such combinations as fruits and vegetables, milk and vegetables, milk and meats, sugar and milk, meat or vege- tables, fats with fruits, meats, or vegetables, or cooked with grains.