The physiology of digestion considered with relation to the principles of dietetics

by Andrew Combe

Among these modifying causes, the varying state of the body at different periods of life ought certainly to be considered as one of the most influential. The differences observed in the constitution of the same person at different ages, are at least as great as those subsisting between different individuals at the same age. In infancy the lymphatic and nutritive functions greatly predominate over the muscular; and if the highly animalized food which suits the latter were then freely administered, it would infallibly induce disease, and fail to afford the requisite nourishment. In manhood, again, when muscular activity and nutrition are at their height, the lymphatic system in abeyance, and the person subjected to laborious exertion, the mild food of infancy would be equally misplaced. In advanced age, another change of constitution occurs. The soft tissues of early life have disappeared, and the whole frame is dry and wasted—a condition which, in its turn, requires food of a different kind from that fitted for either of the preceding stages.

Even the state of the digestive organs at different periods of life is sufficient to indicate a corresponding modification of diet to be proper for each. In early infancy, when no teeth exist, and the muscles which move the jaws are still comparatively small and powerless, and mastication is consequently impossible, milk, from the mother’s breast, is manifestly the only food intended by Nature for its use; and, so long as it can be obtained of healthy quality and in sufficient quantity, no other ought to be substituted in its place. After the milk-teeth have made their appearance, but not till then, a little admixture may be permitted, and gradually and cautiously increased in proportion as dentition advances, and the stomach becomes fitted to digest other food. If, however, the appearance of the teeth be retarded by inability in the mother to furnish an adequate supply of sustenance (which sometimes happens), the deficiency must be made up either by providing a nurse of a healthy constitution, or by other means to be presently mentioned. The former is the preferable remedy; but where a nurse cannot be procured, and the mother’s milk is scanty, the child may, after the third or fourth month, receive, at proper intervals, a small allowance of cow’s milk, diluted with one-third of water, and slightly sweetened. This makes the nearest approach to the nature of the mother’s milk, and is therefore more suitable than any preparation of milk and flour or arrow-root that can be given. Ass or goat-milk answers still better.

The appearance of the first teeth is an indication that the digestive organs have become sufficiently developed to admit of small portions of barley-water panada, thin arrow-root, or milk and water, being given two or three times daily in addition to the nourishment drawn from the mother’s breast, if the latter be at all deficient. Great care must be taken, however, neither to exceed in quantity, nor to give the food too rapidly; for otherwise the stomach will become too full, and be weakened by the efforts it is obliged to make. I have already pointed out the importance of attending to this rule; and in accordance with it, Nature by arranging that the milk shall flow only by slow degrees, has taken care that, in suckling, the child shall receive its food very gradually. The very appearance of the teeth indicates a preparation of the digestive functions for more substantial aliment; and by beginning cautiously the use of small quantities of such simple articles as those above named, and gradually increasing them according to the wants of the system, an excellent preparation is made for the process of weaning, which would otherwise, by its suddenness, be attended with serious risk to both parent and child.

The milk of the parent ought, in every instance, to constitute the food of the infant, unless some very urgent reason prevents the mother from suckling, or renders her milk improper for the child. There is always a relation between the condition and constitution of the mother, and the age and constitution of the infant, which renders this proper, and which cannot exist between the child and any other nurse, but which exercises an important influence on its nutrition. It is well known, for example, that, during the first few weeks, the milk is thinner and more watery than it afterwards becomes. If, consequently, a newly-born infant be provided with a nurse in the third or fourth month, the natural relation between its stomach and the quality of the milk is destroyed, and the infant suffers from the oppression of food being too heavy for its powers. If, again, an infant of five or six months old be transferred to a nurse recently delivered, the aliment which it receives is too watery for its support, and its health in consequence gives way.

In like manner, if the parent be of mature age, her own milk, or that of a healthy nurse of a nearly similar age, will be more suitable to the infant than the milk of a much younger woman; because the constitution of the offspring always bears a relation to that of the mother, and is adapted to the quality of the fluid which Nature has provided for it. I speak, of course, only of the healthy state; for in cases of disease, the mother may be, and often is, the most unfit nurse that can be found for her own child. But as, in such instances, the parents are always guided in their conduct by medical advice, and this is not the place to discuss the treatment of disease, I need not now enlarge upon it.

The leading error in the rearing of the young, I must again repeat, is over-feeding—an error serious in itself, but which may easily be avoided by the parent yielding only to the indication of appetite, and administering food slowly and in small quantities at a time. By no other means can the colics and bowel-complaints, and irritability of the nervous system, so common in infancy, be effectually prevented, and strength and healthy nutrition be secured. Nature never meant the infant stomach to be converted into a receptacle for laxatives, carminatives, antacids, spicy stimulants, and astringents; and when these become necessary, we may rest assured that there is something faulty in our management, however perfect it may seem to ourselves. The only exception is where the child is defectively constituted, and then, of course, it may fail to thrive under the best measures which can be devised for its relief.

Another cause of infantile indigestion, and which is too much overlooked through ignorance of its importance, is vitiation of the quality of the milk, caused by imprudence, neglect, or anxiety, on the part of the mother. The extent to which this cause operates in inducing irritation and suffering in the child is not generally understood; and accordingly, it is not unusual for mothers to display as much indifference to health, regimen, and tranquillity of mind, during nursing, as if the milky secretion, and all other bodily functions, were independent of every external and corporeal influence. Healthy, nourishing, and digestible milk, can proceed only from a healthy and well constituted parent; and it is against nature to expect that, if the mother impairs her health and digestion by improper diet, neglect of exercise, impure air, or unruly passions, she can nevertheless provide a wholesome and uncontaminated fluid, as if she were exemplary in her observance of all the laws of health.

It is no new or uncertain doctrine that the quality of the mother’s milk is affected by her own health and conduct, and that, in its turn, it directly affects the health of the nursling. Even medicines given to the parent act upon the child through the medium of the milk; and a sudden fit of anger, or other violent mental emotion, has not unfrequently been observed to change the quality of the fluid, so much as to produce purging and gripes in the child. Care and anxiety, in like manner, exert a most pernicious influence, and not only diminish the quantity but vitiate the quality of the milk.

As soon, then, may we expect to see a bad tree bringing forth good fruit, as bad management good results; and low must that parent be ranked in the scale of moral beings, who, knowing the relation we have pointed out, can still deliberately sacrifice the welfare of her offspring, by the improper indulgence of her appetites and passions, and by culpably neglecting the duties and restrictions demanded by her own health.

It is a common mistake to suppose that, because a woman is nursing, she ought therefore to live very fully, and to add an allowance of wine, porter, or other fermented liquid, to her usual diet. The only result of this plan is to cause an unnatural degree of fulness in the system, which places the nurse on the brink of disease, and which of itself frequently puts a stop to, instead of increasing, the secretion of the milk. The health and usefulness of country nurses are often utterly ruined by their transplantation into the families of rich and luxurious employers. Accustomed at home to constant bodily exertion, exposure to the air, and a moderate supply of the plainest food, they live in the enjoyment of the best health, and constitute excellent nurses. But the moment they are translated from their proper sphere, their habits and mode of life undergo an unfavourable change. Having no longer any laborious duties to perform, or any daily exposure to encounter, they become plethoric and indolent; and as they are at the same time too well fed, the digestive functions become impaired, the system speedily participates in the disorder, and the milk, which was at first bland, nourishing, and plentiful, now becomes heating and insufficient, and sometimes even stops altogether. The motive which induces the mother to take the nurse out of her proper element is extremely amiable—she is desirous to see that her infant is properly attended to; but the method which she takes to gratify this desire is not on that account the less short-sighted and erroneous. If the nurse cannot be trusted with the child at her own home, care ought to be taken at least that her diet and mode of life be changed as little as possible from those which experience has proved to be most conducive to her health; and the system of feeding, confinement, and indolence, usually resorted to, ought to be strictly prohibited, as fraught with evil to both nurse and child.