The Food Requirements during Pregnancy : Part 3

The Prospective Mother: A Handbook for Women During Pregnancy
by J. Morris Slemons

(Page 7 of 18)

What We Do To Our Food. With the exception of water and mineral substances, the food-stuffs must undergo chemical alterations before they are capable of being absorbed into the body; this is the work of digestion. The digestive processes, the main purpose of which is to break up the carbohydrates, proteins, and fats into substances of much simpler chemical structure, begin in the mouth and are not completed until some time after the food has entered the intestine. As the food moves through the alimentary canal, it is mixed with the various digestive juices containing ferments, such as pepsin, which are the active agents of digestion. Although digestive processes go on automatically, they are, in a degree that is far from negligible, influenced by the mind. Thus, cheerfulness promotes digestion, and not infrequently mental depression may be the direct cause of indigestion. Indeed, it is chiefly in regard to the state of the mind of the prospective mother that the existence of pregnancy may be said to have a bearing, whether favorable or unfavorable, upon her digestion.

The digestive juices are prepared in glands which lie either within the lining of the alimentary canal or adjacent to it. In the latter event the glands are connected with the canal by means of tubes. These glands must be warned when to pour out their secretion, and their very first warning usually comes from the agreeable sensations experienced when we see, smell, or taste inviting food. If we are hungry, our viands attractive, and our surroundings congenial, the stimulus excites a plentiful secretion of the digestive juices; conversely, the opposite conditions, to some extent, check their flow.

The sight of attractive food, as we all know, "makes the mouth water," that is, it calls forth the saliva which contains one of the digestive ferments. Thus, at the beginning of a meal, favorable conditions for digestion are established. The saliva, however, acts only upon starch; and, moreover, its action upon this carbohydrate is weak unless the food is thoroughly chewed and mixed in the mouth. Most of us, perhaps, overlook the importance of mastication, which not only crushes all the food-stuffs, preparing them for efficient digestion, but also stimulates the flow of the digestive juices. Furthermore, by thoroughly masticating our food, we know intuitively when we have had enough, and thus avoid overeating.

In the stomach the digestion of starch is continued for a time, but the chief work of gastric digestion concerns the proteins. They alone are attacked by pepsin, a ferment secreted by the mucous membrane of the stomach. Moreover, since pepsin is able to act only when an acid is present, the gastric mucous membrane also secretes hydrochloric acid.

Just as the digestive glands in the neighborhood of the mouth become more active when we are conscious that desirable food is at hand, so do the glands in the stomach. Mastication also stimulates the flow of the gastric juice, and this flow is greater if we enjoy what we eat. Furthermore, it has been shown that, after entrance into the stomach, the food itself increases the flow of the digestive juices. All articles of food are not, however, equally efficient in producing this effect: thus meat requires more pepsin for satisfactory digestion than bread, and consequently meat calls forth a larger quantity of gastric juice.

Fat in all probability is not digested in the stomach; even starch and protein are not broken down sufficiently by the time gastric digestion is complete to permit them to be absorbed into the body. "The value of digestion in the stomach," as Howell says, "is not so much in its own action as in its combined action with that which takes place in the intestine." It is even possible for satisfactory digestion to take place without the assistance of the stomach. This fact has been substantiated by several cases in which men have lived for years after the stomach was removed to eradicate a disease. It is true, nevertheless, that intestinal digestion can be performed more economically if it begins where gastric digestion normally leaves off.

Of the changes wrought in the food by the various digestive processes, those which are the most profound take place in the intestine. While the food is being moved through this organ - some thirty feet in length - it is reduced to simple chemical fragments, which are absorbed by the intestinal wall. Digestion in the intestine is carried on through the agency of a number of ferments, the more important of which are supplied in the juice manufactured by the pancreas. The pancreatic secretion contains three separate and distinct ferments, which act respectively upon carbohydrate, protein, and fat. The absorption of fat, however, is materially assisted also by the action of the bile.

A part of what we eat always escapes digestion; the unused portion, it has been estimated, is somewhat less than one-tenth of an ordinary mixed diet. The residue from vegetables is notably larger than the residue from meat. The undigested portions of all the food- stuffs collect in the lowermost portion of the intestine and form a part of the feces. Here also are gathered the indigestible material we have eaten, the products of bacterial decomposition in the intestine, and other waste substances that the body should throw off.

How Much Food is Needed During Pregnancy? In connection with the development of the child we have already referred to the difference in the purpose of the constructive processes which go on in the earlier months of gestation and those which take place in the later months. In a general way the first half of pregnancy is occupied with the formation of the embryo from relatively simple structural elements, the second half with its growth into an infant, which acquires ninety per cent. of its substance and weight at birth after the fifth month of embryonic development. A similar contrast may be observed in the nutritional processes of the mother. Often, at the beginning of pregnancy, the appetite is poor and there is indisposition of one kind or another, with the natural result that there is slight if any change in the mother's weight; whereas later a period ensues when her appetite increases, her health improves, and she gains in weight.

Since it is natural that the weight of the mother should remain practically stationary during the early months of pregnancy, it is clear that a diet which has previously been ample will likewise be sufficient for some time after conception has taken place. To most persons, however, it is not clear that the quantity of food ordinarily eaten will suffice also during the later months of pregnancy. On the contrary, popular opinion holds that the prospective mother "should eat for two." It is not unimportant to point out the erroneous character of this superstition, because overeating during pregnancy is much more likely to provoke discomfort than insufficient nourishment.