Mechanically Acting Cathartics
( Originally Published 1938 )
First of all, let us consider bran, popularly called a "food" laxative. While it was believed for a time to have a chemical action, it has now been established that its action is mechanical. It increases the bulk of the intestinal contents and by reason of the spicate shape of its particles irritates the nerve endings of the intestinal walls. This twofold action induces peristalsis and the feces are expelled.
On first thought it would appear that bran was an economic, pleasant and convenient remedy for constipation. However, it has some decided disadvantages and in many cases is a positive menace to health. Some persons find that bran is highly irritating to the mucous lining of the intestinal tract and therefore may result in serious injury. This is particularly true of persons suffering from ulcers, colitis or other. disorders of the intestinal tract. You will recall, too, that, while atonic constipation is by far the commoner, spastic constipation is frequently found, even in persons who are otherwise healthy. Bland, soft diets are indicated in cases of this type of constipation. Bran would only intensify the spasticity, necessitating mechanical or surgical removal of the obstruction. If spastic constipation were always recognized as such and treated accordingly, danger from bran would be eliminated. Unfortunately this is not always the case.
Moreover, it has been the experience of many individuals suffering from atonic constipation that when they eat bran, either in large doses over a short period of time or small doses over an extended period of time, their colons become irritable. Sometimes vague abdominal pains occur with bloating, belching and flatulence.
The prolonged use of bran may result in malnutrition, which implies serious constitutional disturbances and the breakdown of general health. Bran is intended as a remedy for constipation due to insufficient bulk. This implies that the ordinary intake of food is not normal in bulk and that, therefore, in most cases, is deficient in the nutritive elements. Bran, while supplying the deficient bulk, does not supply the missing nutrition, despite the claims made for its mineral and vitamin content. Such elements are relatively small in amount in the quantities usually consumed of the commercial bran preparations. Moreover bran has a tendency to decrease the amount of digested food available for absorption by hastening its passage along the intestinal tract as well as affecting the digestive process itself.
Bran may be a source of danger in still another way.
Frequently persons, not finding any relief from constipation in the consumption of small amounts of bran, take larger quantities which are certain to prove a source of irritation. But probably the greatest disadvantage and harmfulness arises from the fact that bran does not tend to really correct intestinal atony, but it merely temporarily relieves it, and tends to aggravate it, since, as the intestinal muscles and nerves become more and more used to the increased bulk and irritation, larger quantities of the food must be consumed to stimulate peristalsis.
There are many preparations on the market such as agar-agar or Japanese seaweed that effect elimination through mechanical means. The effectiveness of agar-agar and similar products lies in their ability to absorb and hold in their porous structure large amounts of water, thus preventing the absorption of water by the walls of the intestines. They have but slight effect on the mucous membranes and nerve endings and therefore do not aggravate a tendency towards constipation. However, they have no corrective properties and therefore are efficacious only as long as they are used, and sometimes even cause intestinal obstruction.
Saline cathartics or salts, the various mineral water and aperient preparations act principally by causing an increased amount of water in the intestines. This increased amount of water is derived from the form of the cathartic itself which is either dissolved in water before consumption or is already dissolved in water when purchased, from the retention of water already in the intestine, and from the absorption of water from the blood vessels in the intestinal walls. This absorption of water is based on a principle which is known in physics as the principle of osmosis when two fluids of different densities or thickness are separated by a permeable wall such as the cell walls of our bodies, there is a tendency for the thinner fluid to flow toward the heavier fluid until they are both of the same density. The weight of the liquid, plus the stimulation of the nerve endings by the pressure against the intestinal walls causes the purgation.
In addition to this mechanical action which purgatives of this group possess, many of the patented preparations are intended to be definitely alkalizing by reason of the ingredients they contain, and not merely because they rid the body of the poisonous wastes which are directly or indirectly disturbing the acid-base balance. Some, too, are designed to have a specific effect on a particular part or parts of the alimentary tract, such as the liver, for example.
It is clear that salines, by causing the absorption of body fluid into the intestines, produce dehydration. It is for this reason that, particularly when insufficient water is consumed with them, individuals may become unduly thirsty. In certain constitutional disorders dehydration is often very desirable and even necessary, but in persons who are otherwise normally healthy it is neither desirable nor beneficial. The very fact that the system craves water and manifests this craving in the form of "thirstiness" is sufficient proof.
This group of purgatives has some other disadvantages which must be thoughtfully weighed when selecting a remedy for constipation. Because of the nature of their action, they must be taken when you are up and moving around, and they are far more prompt in action when some food is taken shortly afterwards preferably a light breakfast. (On the other hand, they cannot be taken shortly after a meal.) Hence they cannot be taken at night and this is a serious source of inconvenience to many people. Nor can they be given to persons lying in bed if quick and thorough action is desired.
Moreover, if they are somewhat concentrated, salines remain in the stomach until sufficient fluid has been absorbed to make them the same density as the blood. During this time they irritate the stomach and the mucous membranes and the passage is delayed.
When they reach the small intestine they have an advantage, it is true, over purgatives of the cascara and castor oil type in that they do not affect the passage of the chyme their action is principally on the large intestine. However, in some cases they produce nausea, headache and abdominal discomfort, even pain, without affecting the bowels. You yourself, if you have ever taken a purgative of this type and undoubtedly you have must have experienced at least a very uncomfortable, heavy feeling in your abdomen. If, in spite of this, you still indulge in salines and they are useful at times you must be doubly careful not to take more than enough for a single bowel movement, especially if you are suffering from hemorrhoids.
Keep in mind that this popular group of purgatives used under the guidance of a physician are exceedingly useful. But they are no more curative than the other remedies we have just discussed. Indeed, like them, they have a tendency to aggravate constipation. Moreover, it will be recalled that most of this group have special alkalizing properties. Since it is very easy to become a victim of the salts habit, one is in danger of becoming over-alkalinized. Since the so-called acid stomach or acid indigestion is largely functional and is frequently caused by constipation, it stands to reason that in most cases the acidosis will disappear with the simple flushing of the intestines without the addition of drugs.
Liquid petrolatum in various forms and under various proprietary names still occupies a prominent place in the treatment of chronic constipation and similar intestinal disorders. It acts merely as a mechanical lubricant and increases the bulk of the intestinal contents to a certain extent. However, it does not increase peristalsis to any noticeable degree in reality it merely makes more effective peristaltic action which is already existent. It is more valuable in conditions in which hemorrhoids or fissures are present or when some part of the passageway through the intestines has been narrowed.
In some emulsions of liquid petrolatum agar is added and it is claimed that the agar makes the product particularly effective. But this is misleading because there is not enough agar present to have any value and moreover, there is enough water in such preparations to nullify any possible benefit from the agar. Agar, it will be recalled, acts by absorbing and retaining moisture.
Mineral oils are of only temporary value and often increase intestinal sluggishness by lessening the amount of intestinal muscular exercise, although in eases of spastic constipation they are frequently valuable agents as they decrease the irritability which is causing the constipation.
Not only are mineral oils of doubtful value in chronic constipation, but they have a tendency to interfere with digestion and assimilation. Moreover, they are apt to produce slight nausea, especially in persons whose stomachs are sluggish in their action and slow to empty. They have another disagreeable feature, too, of which many persons complain. If a sufficient quantity of oil is taken to bring about an evacuation of the bowel contents, the oil frequently leaks out from the bowel, since none of it absorbed, even to the extent of staining wearing apparel and bed clothing with an unsightly stain difficult to remove.