and taste of food. As Pawlow has shown, the smell or sight of food will excite the flow of the gastric secretion, and this in turn will produce an appetite. Simple bitters or some form of alcoholic drink will at times induce this sensation. The appearance of badly prepared or improperly served food will often dispel the appetite. In children the appetite is usually good, whereas in the aged it is lessened. Some persons have voracious appetites, and abnormal craving for food. This is often the case in diabetic and other conditions, when, at times, the appetite can not be satisfied. 4. Temperature of Food.-The temperature of food when taken is of considerable importance. The ideal temperature is that of the body, from 98° to 100° F. (Uffelmann), the limits of safety being between 45° and 130° F. According to Hutchison, extremes of temperature of food are apt to give rise to gastric disturbances, such as gastric catarrh. Uffelmann states that a drink at a temperature of 122° F. increases the body-temperature 0.1 to 0.3 degree C. It is believed by many that ulcer of the stomach, so common in cooks, is often due to the taking of too hot foods. Hutchison considers that the proper temperature of water intended to quench the thirst should be between 50° and 70° F. 5. Rest and Exercise before and after Meals.It is often advisable to rest, but not to sleep, after meals. The larger part of the work of the stomach should be completed before retiring at night, otherwise the sleep is apt to be disturbed. About one or two hours should be allowed to elapse between a light evening meal and bedtime, and three or four hours between a heavy meal and sleep. From personal observations (see the section on Rest and Sleep in Gastric Disturbances) the authors have concluded that digestion is improved by rest after meals, but impaired by sleep. In many instances a period of rest before eating meals is a valuable aid to digestion. Violent exercise immediately after meals inhibits digestion, whereas moderate exercise one or two hours after meals materially aids this process. 6. Food and Emotion.-Severe mental strain and strong emotion disturb the digestion, and for this reason food should not be taken until a period of rest and composure has intervened. On the other hand, pleasurable sensations aid the digestion, and pleasant conversation at the table is therefore to be recommended. 1 The Work of the Digestive Glands. THE RELATION OF FOOD TO VARIOUS INHERENT CONDITIONS. Inquiries are often made concerning the relation of food to various conditions, such as the influence of sex, race, and the like. These conditions will now be briefly discussed. Heredity.-Certain systemic conditions and diseases, or the tendencies to them, are inherited. Those of especial interest, from the standpoint of diet, are leanness, obesity, diabetes, gout, and alcoholism. Food idiosyncrasies are also often inherited. Among these are the liability to the development of urticaria or poisoning from the eating of strawberries, crabs, etc. In the case of obesity, gout, and the like, the diet should be regulated with a view to preventing these diseases. Sex. As a rule, women eat and require less food than men. This is probably due in large measure to the indoor and sedentary life led by so many women. Under equal conditions sex has little influence on food requirements. Atwater states that under similar conditions women require four-fifths as much food as men. Age in some measure influences the quantity of food taken; a child requires proportionately a larger amount of food than an adult. Atwater1 thus compares the amount of food required in childhood with the quantity needed by a man at moderately active muscular work: 15-16 yr. requires 0.9 the food of a man at moderate work. Boy Girl Girl A growing active boy usually requires more animal food proportionately than an adult, whereas a man of middle age requires more than an old man. Race. The food of different races varies widely, but this is due, for the most part, to the varying conditions under which they live, and especially to the food-supply that is most available by reason of cost and the ease with which it can be pro 1 Principles of Nutrition and Nutritive Value of Foods, Farmers' Bulletin No. 142, United States Department of Agriculture. cured. The Eskimos subsist largely upon raw or partly cooked meat and use large amounts of fat. In the torrid zone the natives eat largely of cereals, fruits, and vegetables. In the temperate zones the diet is mixed, and is dependent largely upon social and financial conditions, being of the most varied character in the case of the well-to-do, whereas among the poor it is apt to be made up of the cheaper meats, breads, and vegetables. Soldiers and travellers from the temperate zones, going either north or south, usually require approximately the same varieties of food they had at home. Soldiers in the tropics crave and eat meat, when they can obtain it, in almost as large quantities as they would at home, and even after years of life in the tropics do not make any great change in their diet. Major Charles E. Woodruff, Surgeon U. S. A., expresses the following opinion: "All natives of the tropics (where civilization causes over-population) are in a condition of nitrogen starvation and need much more nitrogen than they can possibly get. The old standards of teaching that we should eat as the natives is most vicious. They do not eat meat because they can not get it. They crave it, need it, and eat it when they can. On account of the destructive effects of the concentrated tropical actinic rays on protoplasm we need more nitrogen than at home. Please don't copy the old falsehood that we need less. It is also true that we need fat, as it furnishes energy better than carbohydrates. It is eaten in preference to starches and sugars for this purpose by workers when they can afford it, but they take to starch (rice) because it is cheaper. It is incorrect to say that it overheats. It does not overheat us, and it is false to say that fat is not needed in the tropics." Climate. In close relation to the question of race is the question of temperature and climate. There are many differences of opinion, as one can gather from Major Woodruff's words. In regard to the subject he says: "Climate affects diet mainly by the supply it affords." The main difference lies in the amount of heat and energy that must be supplied. In cold climates more food, especially fat, is needed, because the amount of heat required to maintain the warmth of the body is greater. If the individual is doing a large amount of work, a proper quantity of food must be supplied whether the climate is hot or cold. When the individual is in a hot climate and is doing little or no work less food is required. Season. What has just been said regarding climate applies also to season. Somewhat more food is required in winter than in summer, in order to supply the extra heat. People who are well clad and well sheltered need less food in cold weather and in cold climates than those who are poorly clad and exposed to the elements. (See the abstract from Woodruff in the section on Army Rations.) Size and Weight.-Other things being equal, the larger the body the more food is needed. This is an important point in feeding infants, and is discussed in the section on Infant Feeding. If the food-supply in childhood is insufficient, the child will be undersized. As applied to races, however, this rule is theoretic, and, since evidence to the contrary exists, the subject requires further study. The weight of the individual is very important in the management of diseases that are influenced by diet. The weighing of patients is a practice that is much neglected. Weighed with the same scales at different times during the day the weight of an adult will vary, on the average, two pounds, and in many instances as much as three. With changes in clothing the variation may be much more. The differences in weight are governed by the amount of food and drink ingested, and by the condition of the bowels and bladder, whether they have been emptied or are full. It is easy to see how errors may arise unless all these things be considered. Patients are easily buoyed up or depressed as a result of weighing, and care should be exercised to avoid the latter. If the patient is weighed in his clothes, the same garments should be worn at each weighing. The relation to mealtime and to the voiding of urine and feces should also, so far as possible, be the same at each weighing. The patient should be instructed not to drink water for the sake of increasing his weight. Rest and Exercise.-Much less food is required during rest than during exercise. In exercise the muscular activity increases oxidation and tissue-waste, and this waste must be counterbalanced by an increased consumption of food. According to Atwater: A man at hard work requires 1.2 of the food of a man at moderate work; a man at light muscular work requires 0.9 of the food of a man at moderate work; a man of sedentary habits requires 0.8 of the food of a man at moderate work. Rübner states that: (1) At rest a man requires 2500 calories; (2) at professional work a man requires 2631 calories; (3) at moderate muscular work a man requires 3121 calories; (4) at severe muscular work a man requires 3659 calories; (5) at hard labor a man requires 5213 calories. Individual tendencies have some effect on the amount of food required. There are many persons who eat very sparingly and who nevertheless become obese ; others partake of an unusually large quantity of food and never fatten. This is due probably, as Hutchison points out, to the fact that the 'activity of the cells in certain individuals is greater than in, others, and leads to a more rapid breaking-down of food and a greater waste of heat." The great tendency with most persons is to overeat, in consequence of which fats are stored up; as a result, obesity or gastro-intestinal or other disturbances occur, and thus the excess of food is eliminated. At times the reverse condition-that of consuming too little nourishment-occurs. The period during which an individual can subsist without food varies, and depends largely upon the amount of exercise taken and upon atmospheric conditions, such as moisture and temperature. A condition more frequently met with than actual starvation is a one-sided or improperly balanced diet-that is, one in which one or the other of the food elements is taken in excess, while the other elements are diminished or lacking. Thus if an individual eats excessive quantities of meat and no vegetables, the diet is too rich in proteins and too poor in carbohydrates; again, if large quantities of butter and rich cakes be eaten and no meat or vegetables, the diet will be too rich in fats and carbohydrates and too poor in proteins, and may, therefore, prove harmful. As a rule, in a badly balanced diet the number of calories is too small to meet the requirements. The following diet-list, given by Mrs. E. H. Richards, shows a common invalid diet too low in proteins: A Common Invalid Ration Too Low in Protein.-(Mrs. E. H. Richards.) |