This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Persons who are constantly employed in mental labour, and consequently lead sedentary lives, usually find from experience, sooner or later, that they must pay attention to their diet in order to maintain the best condition of health. Energy diverted for mental work is apt to be at the expense of digestive activity, consequently it is important that the meals should be of such a character as not to unduly tax the stomach and intestines. As a rule, meat should be eaten but once a day, and then only in moderation, and persons who are not of strong physique do well to replace meat for a time by other varieties of animal food which require less time and energy for their digestion. Milk, eggs, fish, and abundant fresh fruit, with light, porous, and dry bread, should constitute their staple dietary.
Brain workers may suffer from lithaemia, which is undoubtedly often due to other causes than dietetic errors, such as anxiety, worry, and overwork. Patients of this class do better with a good, full, nourishing diet than by any attempt at restriction, provided their food is thoroughly well cooked and is light and digestible. They should avoid saccharine, fatty, and purely starchy dishes, but they need meat, and may have a moderate variety of fruits and fresh green vegetables.
The brain contains nearly three times as much fat as may be found in the muscles, and in nerves an even larger percentage is present. For this reason carbohydrates and fats are of value for brain workers who are not lithaemic, and the latter food may be supplied in the form of cream, butter, or fat well-cooked bacon.
It is believed by some writers that the fact that fat is good food for brain workers depends upon the ease with which it develops energy with less complex metabolism than starches, and the nervous energy of many Americans is sometimes attributed to the greater consumption of fat in this country as compared with Continental Europe and England.
The popular idea that fish has some specific action as a brain food on account of the phosphorus which is present in some species in considerable amount, and which is also an ingredient of nerve tissue, is not founded upon fact. Fresh fish is very wholesome, and by replacing meat in the menu less labour is required of the digestive organs, and some forms of fish contain abundant fat or oil, but aside from this, fish cannot be said to be especially a brain food. It has been pointed out elsewhere (p. 127) that the tribes of man who live very largely upon fish are by no means noted for their intellectual development.
For brain workers who desire to keep in good health the alternative is either to take at least two hours of rest after a noon dinner or else to eat a light meal at noon and dine later in the day. This fact should be recognised in the arrangement of meals for college students. It is far better during the active hours of brain work to supply only such food as is necessary for prompt force production without calling upon the digestive organs for the expenditure of much energy in elaborating food which is only needed for storage.
Luncheon may comprise such articles as a roast potato with butter and cream, or beans and bacon, one or two light sandwiches made with a slice of game or a relish of some sort, cheese, lettuce or salad, and a baked apple and cream.
Dinner should be a hearty meal with soup, a roast or joint, vegetables, and a light farinaceous pudding. If evening work must be done, there should be an interval of at least an hour for rest and recreation. A generous meal is easier digested after work is done, and makes the best preparation for the next day's toil.
A Work Ration for a Professional or Literary Man (Mrs. E. H. Richards)
Additional liquid - tea, coffee, or water
Overeating should be studiously avoided. Loading the system with incompletely assimilated food products impairs intellectual activity and exhausts the nervous system. If some special task requires long hours of work and absorbing concentration, it may be better to eat but little at a time, and take one or two extra lunches during the day. When such labour proves fatiguing, alcohol may be temporarily employed, but only with the meals, and not as a stimulant between. The quantity may be regulated somewhat by the appetite, but it should never be large. If a glass or two of claret or Burgundy or of malt liquor with lunch or dinner improves the appetite for solid food and aids its digestion, it is beneficial, for, as Chambers wrote, " it stays the weariness of the system and allows the nerve force to be diverted to the digestion of the meal " but to labour on and "continue to take this anaesthetic between meals is inconsistent"; and "when any extraordinary mental toil is temporarily imposed, extreme temperance or even total abstinence should be the rule, for mental activity makes the brain bear less alcohol than rest and relaxation".
The varieties of beverages named are all better than port, sherry, or the stronger liquors.