WHAT is a food? This is not quite so easy a question to answer as some people might suppose. Any substance which is capable of being digested and converted into the tissues of the body is a food. This is the scientific definition; but there are many substances which have been eaten, and which have actually helped to sustain life under emergencies, which we are not in the habit of looking upon as food in an ordinary way. For instance, in times of siege, leather has been actually eaten by starving people, but we don’t consider leather a food. Therefore in practical life it is only those substances which contain a considerable amount of digestible material that are to be regarded as foods.
Moreover, the question, What is a food? can only be answered by each individual for himself. What is a food to one man is not necessarily a food to another. Such an innocent thing as mutton, for instance, would be said by most people to be good food for everybody, and yet I know those to whom the least bit of mutton is dangerous poison. Many people can eat mackerel and enjoy it without feeling any after-effect; in others the smallest portion of it will set up choleraic symptoms. Some people are so sensitive that fish of any kind will cause violent nettlerash. I have known others who are sure to have a severe fit of asthma if they even smell roast hare. Finally, some people are poisoned if they eat rice, and can detect its presence in beer by their symptoms when merely a few grains of it have been put into the beer at the time of bottling.
In our definition of “food,” therefore, we must make room for exceptions; it is not all substances containing nutriment that are food for everybody.
Foods are divided into two kinds–those in which the nitrogenous or albuminous elements predominate, and those which contain the carbon elements in the greater proportion.
To the nitrogen class belong lean of meat, cheese, French beans, peas, lentils; whereas the carbon class is represented by fat of meat, butter, farinaceous foods, sugar, potatoes, and bread. The only perfect food is milk, containing both elements in good proportions. Eggs also contain both elements, but they are not such a perfect food as milk, as they do not contain the necessary salts in solution as milk does. Of course, there are other things in foods besides these two predominating elements, though this division makes a useful classification. And it must not be supposed that the members of one class have none of the elements characteristic of the other. It is only the proportion which serves to distinguish them; meat contains carbon as well as nitrogen, and bread contains nitrogen as well as carbon. Nor are the members of the same class alike; rice and bread are both in the carbon class, but rice contains less nitrogen than bread.
There is another food element the importance of which has been rightly emphasised by Dr. Lahmann, namely, food-salts. These are contained in milk in the right proportion as regards other food elements, and also in the right relative proportions among themselves. Soda, potash, and lime salts are the principal. These are contained in the various fruits and vegetables in sufficient excess to make up for the deficiency of them in meats, and pulse foods, such as peas, beans, and lentils. It is important that vegetables should be cooked by steaming, as the common practice of boiling them boils most of their salts out of them and common table-salt does not make up for the deficiency.
Cow’s milk contains 0.7 per cent. of food salts, which have the following percentage composition :-
Potash, K2O…. 24.67
Soda, Na2O…. 9.70
Lime, CaO…… 22.05
Magnesia, MgO…. 3.05
Oxide of Iron, Fe2O3.. 0.53
Phosphoric Acid, H3PO4.. 28.45
Sulphuric Acid, SO3.. 0.30
Silicic Acid, SiO2…. 0.04
Chlorine, Cl…. 14.28
Meat, white flour, potato, and peas contain very much less than the proper proportion of soda, lime, and chlorine than the standard of milk. Spinach, cabbage-lettuce, and carrot contain more than the standard. Apple and strawberry contain more than the standard of soda but less of lime. This shows the necessity of plenty of fresh fruits and green vegetables in the dietary of a meat-eating people. The use of common table-salt is no substitute for the lack of the right food-salts. Chloride of sodium is more of a stimulant than a food. It renders too rapid the passage of fluid from the tissues and causes an abnormal thirst. Salted meats are not such valuable foods as fresh meats; and for this reason : Three-fourths of the weight of fresh meat consists of water; but in contact with salt fresh meat loses some of its water, which passes into the brine and carries with it a considerable part of the effective organic and inorganic constituents of the meat (Group-Besanez). A similar process of “pickling” goes on in the bodies of those who eat excessively of salt. Another effect of over-indulgence in salt is the creation of acidity.
1 *Natural Hygiene, H. Lahmann. M.D. London: Swan Sonnenschein*.
Food, then, to be satisfactory, must contain all of these elements; and the proportions should be about fifteen of the carbon class (fat and sugar), and five of the nitrogen class (albumen), and one of salts. It is in order to keep the proportion between carbon and nitrogen that potatoes are taken with meat, and are better for that purpose than bread, which itself contains much of the nitrogenous elements. Cheese by itself is much too strong a food, and needs to be taken with bread, and perhaps butter as well.
Proper food, then, which I have said is the first requisite for the healthy stomach, consists of food-substances combined in proper proportions according to their nature, and, of course–if cooked at all–properly cooked.
There is much dispute about alcohol, as to whether it is a food or not in the proper sense of the word. If it be a food, it is an uncommonly poor one. It is a carbohydrate, that is certain, and it is capable of being absorbed into the blood; but it no sooner gets there than every organ does its best to get rid of it, and if any of it undergoes a change in the blood, it can only be a very small proportion. It is a safe rule to make, never to consider anything as a food when there is any doubt about whether it is a food or not. There are plenty of things about which there is no doubt. Let these be taken as food, and if the doubtful articles are taken at all, let it be for some other reason, and not with the idea of nourishing the body.
Alcohol brings me to the question of drinks. Actually there is only one drink-water. Beer, tea, coffee, and the rest, are drinks, it is true, but they owe their property of thirst- quenching to the water they contain, not to the substances which flavour them. Milk is a drink, but it contains so much food, which becomes solid as soon as it enters the stomach, that it should only be taken as a drink at mealtimes by those who are not able to take much solid food. It is well, as mentioned in the previous chapter, not to drink much of any liquid during a meal, but to take a good draught before it, or after it is over.
Some people have a great distaste for cold water, and some cannot digest it. For them hot water or toast-water may be substituted, when other drinks are objectionable.
The second great requisite for the stomach, that I pointed out, is -Proper quantity of food.
The stomach requires a certain mass of food for it to work on. A healthy stomach will have nothing to do with essences or condensed foods; it requires bulk in order that its muscular coat may have something to grasp and contract on, and its secretion something to mix with. It is for this reason that the starchy foods, like potatoes, are the best to eat with meat, because the latter contains nutriment in so condensed a form that substances less rich must be added to make up sufficient bulk. When foods are prescribed in small quantity, and in light form, it is because the stomach is in an abnormal condition.
This leads me to speak of the third requisite-Proper rest.
When the stomach has dealt with a meal, pouring out its secretion, and by means of its muscular action reducing it to a proper state for further digestion in the intestines, it passes it on. Then the stomach has rest, and the other organs take up the work. The effort it has gone through is no light one, and it needs time to recover itself. If this time of rest is broken by subsidiary meals, or indulgence in confectionery, the stomach resents it, and the result is indigestion. Unless under special circumstances, no food whatever should be taken between meals, and a good five hours should be allowed between one meal and another. Three meals a day-at 8, I, and 7 o’clock is the best arrangement in an ordinary way. The middle meal should be very light if much active brain-work has to be done in the afternoon. In the morning the stomach is most vigorous, and a substantial meal can be taken then, though active work must be begun soon after. In the evening the powers of the body are more exhausted by the day’s exertions, and yet a substantial meal can be taken at that time, as it is followed by a period of rest and relaxation.