In old age there are inevitable changes which slowly occur in the circulatory and digestive organs of the body. Although the general health may still be unimpaired, the circulation is less vigorous, and the nervous system less active to external stimulation. There are degenerations in the secreting organs with a tendency to deposition in the tissues of phosphate and carbonate of lime, derived from the food. Absorption is less active, and there is diminished adaptability of the whole system to alterations in environment, and much less ability to meet the requirements of emergencies, such as sudden calls for the use of muscles or mental strain. The muscular tone of the intestine is apt to deteriorate and produce constipation and a relaxed condition resulting in its dilatation. The circulation through the mesenteric vessels and those of the portal system becomes inactive, with a consequent reduction in the rate of absorption, and a diminished and altered gland secretion in the liver, pancreas, etc.

For these reasons the digestive powers are less vigorous, but, on the other hand, there is not so much demand for fuel in the body as in earlier years. The vital processes conducted by the circulation, respiration, and metabolic changes in the tissues are very inactive, and there is a correspondingly restricted expenditure of energy.

Persons of very advanced age - those who are past eighty years or more - can sometimes live comfortably on an astonishingly small quantity of food. J. Forster examined the food of the inmates of an institution for elderly widows and found that many of the old women subsisted very comfortably upon a diet containing, in grammes, albumin, 67; fat, 38; and carbohydrates, 266.

Much depends, however, upon the rapidity with which the changes above described have developed, and dietetic rules for such cases are not to be based upon a definite period of years so much as upon the degree of senility which is present in individual cases.

Sir Henry Thompson (Diet in Relation to Age and Activity), in commenting upon the progressing diminution with advancing years of physical energy and of the power to eliminate waste material from the body, and the consequent harm of overeating, says that if a man past his half century of life "continues to consume the same abundant breakfasts, substantial lunches, and heavy dinners which at the summit of his power he could dispose of almost with impunity, he will in time either certainly accumulate fat or become acquainted with gout or rheumatism, or show signs of unhealthy deposit of some kind in some part of the body - processes which must inevitably empoison, undermine, or shorten his remaining term of life.... The typical man of eighty or ninety years is lean and spare, and lives on slender rations".

In the dietetic treatment of cases of extreme old age the rules which are naturally suggested are:

1. To diminish the total quantity of food ingested.

2. To give food at frequent intervals in small amount.

3. To give only easily digestible food, which does not produce too large a residue of waste matter, either in the intestinal canal or in the form of excrementitious material in the blood.

It is an undoubted fact that, having reached an advanced age, a man may often prolong his life and greatly add to the comfort of his remaining years by adhering to these rules. Yet there are many instances of those whose constitutional vigour is so great and whose appetite for the good things of the table remains so keen that they are unable or unwilling to listen to the dictates of reason. I recollect an instance of a gentleman who, in the enjoyment of almost perfect health at the advanced age of ninety-four, suddenly terminated his life by an uncontrollable indulgence in lobster salad. The idea is prevalent with some people that the quantity of food and stimulants should be increased pari passu with age, but this is as wrong in theory as it is pernicious in practice, and the simple fact that an article of particularly rich or hearty food has been enjoyed with impunity for many years is no argument that it can be indefinitely taken in the same degree, although this reasoning is very often encountered.

In commenting upon Professor Humphrey's report upon centenarians, made for the British Medical Association, Dr. Yeo observes: " Their habits in eating and drinking tended, as a rule, to great moderation in both.... Of animal food the majority took but little.... The exact quantity is mentioned in nine instances: One took 12 ounces, one 6, one 5, and six 4 ounces daily. In the use of alcoholic drinks we also find evidence of great moderation".

Some more recent investigations of the dietetic habits of men over one hundred years of age show considerable diversity; thus, for example, some were found who ate but one meal a day, while others ate four or five; some drank but little fluid, others took a great deal; some were total abstainers from alcohol, and others were not.

Persons who attain to very advanced age are almost invariably of spare habit, and the universal testimony in regard to centenarians is that they have never abused food or drink, and that in the latter years of life, at least, they have been very abstemious in the use of meat. In fact, Nature usually furnishes a hint in this direction by depriving them of their teeth, making it practically impossible to eat animal food, which requires mastication, and, as Yeo suggests, "if artificial teeth are used for the purpose of continuing a diet composed of animal flesh, they will not prove an unqualified advantage".

Next in importance to diminishing the quantity of food in the diet of the aged (especially the proportion of fats and proteid material) should be considered the necessity of regularity in diet, both in regard to the general character of the food taken and the times of eating.

If the teeth are absent, tough vegetables and meats must be avoided, yet the food should not be wholly fluid, for some mastication should be performed in order to maintain the salivary flow. Plenty of time should be allowed for this purpose.

Any sudden changes in diet should be avoided, and the intervals between the ingestion of food should not exceed six or eight hours.

It is very common for elderly people to awaken early in the morning at three or four o'clock and to be unable to drop off to sleep again, but if they have some light form of nourishment at the bedside, such as a glass of milk or a little gruel, which they can take at that time, they will often continue their sleep.

Malt liquors are very good for the aged, and a moderate amount of alcohol acts as a tonic and supplies them with needed energy for digestion and other functions.

Yeo gives the following suggestions in regard to the diet of the aged, which are so useful that they will be quoted in full:

" Of animal foods best suited for this time of life the following may be mentioned. When the organs of mastication are altogether inefficient these foods should be minced or pounded into a paste or otherwise finely subdivided:

"Young and tender chicken and game and other tender meats.

"Potted chicken, game, and other meats, sweetbread.

"White fish, as soles, whiting, smelts, flounders, etc. Best when boiled.

"Bacon, grilled; eggs lightly cooked or beaten up with milk.

"Nutritious soups, such as chicken or fish, purees, beef tea, mutton and chicken broths.

"Milk in all forms, when easily digested.

"Beef tea and milk supply the needed mineral substances, and the former is an excellent stimulant.

"The addition to milk of an equal quantity of Vichy water, warm, or of warm water, will often help to make it agree.

"Of vegetable foods the following are all suitable:

"Bread and milk made with the crumb of stale bread and without any lumps.

"Porridge and oatmeal gruel.

"Puddings of ground rice, tapioca, arrowroot, sago, macaroni with milk or eggs and flavoured with some warm spices, or served with fruit juice or jelly; bread and butter, at least a day old; rusks for soaking in tea, or milk, or water.

"Artificial foods, consisting of predigested starches. The digestive ferments are scantily provided by the digestive organs at this age, and soluble carbohydrates are valuable for maintaining the body heat.

"All farinaceous foods should be submitted to a high temperature for some time, so as to render the starch granules more easy of digestion.

"Vegetable purees of all kinds may be taken in moderation - e. g., potatoes, carrots, spinach, and other succulent vegetables.

"It is important that the use of potatoes and fresh vegetables should not be neglected; otherwise a scorbutic state of the body may be engendered.

"Stewed celery and stewed Spanish or Portugal onions.

"Stewed or baked fruits and fruit jellies and the pulp of perfectly ripe raw fruits in small quantity.

"The acidity of certain stewed fruits may be advantageously neutralised by the addition of a little bicarbonate of soda so as to avoid the use of a large quantity of cane sugar to sweeten it, as this is apt to cause gastric fermentation and acidity. In stewing fruit, about as much soda as will cover a shilling should be added to each pound of fruit.

"Aged persons often require their foods to be accompanied with some kind of condiment, which promotes their digestion and prevents flatulence.

"Caviare and the roes of smoked and salted herrings are of this nature.

"For sweetening food, milk sugar is much less prone to excite acid fermentation than cane sugar.

"A very digestible form of fat - when it is needed - is cream, mixed with an equal quantity of hot water and about ten drops of sal volatile to each fluid ounce".