Know that most stomach diseases are the result of indigestion. Avoid indigestion and avoid its causes, that is, foods that are harmful due to their quantity, quality or because they are unusual, as well as bad air, which interferes with good digestion. One of the enemies of the stomach is overfilling, for it does not fatten the glutton’s body, since the food in it is not digested and the body does not feed on it. If a person stops eating while the remainder of his appetite is still retained, he becomes fatter, since his stomach digests food better.
Know that if a food is not suitable for the stomach by itself, and not as a result of mixing with other dishes, then it is not suitable either in quantity or in quality. In both cases, food, if it is rather light, floats up and requires removal by vomiting, and if it is rather heavy, it settles and requires removal through laxation. It also happens that part of the food floats up, and part settles due to the difference in the degree of lightness and heaviness and the difference in the movement of the winds arising in the stomach; then she requires both vomiting and relaxation. Know that holding back winds and feces is very harmful, because feces sometimes return because of this and pass from one bend of the intestines to another, heading upward until it returns to the stomach, and this causes great suffering. Sometimes this even causes something like intestinal obstruction, nausea occurs and appetite decreases. The winds also sometimes return to the stomach. The vapors then rise from the stomach to the brain, causing great suffering and spoiling what is in the stomach.
Know that substances that do not have astringent properties, squeezed juices in particular and all other substances in general, are harmful to the stomach. All oils relax the stomach and are not suitable for it; The most harmless are olive oil, nut oil and pistachio oil. Medicines and nutrients that are in most cases harmful to the stomach include pine nuts, beets, mountain basil, turnips, unless they disintegrate due to intense cooking, sorrel, quinoa, pigweed, unless eaten with vinegar, with murri and with olive oil. This also includes fenugreek and sesame, because they weaken the stomach; milk is harmful to the stomach, as is the bone marrow and brain of various animals. Wines are harmful if they are thick and young; among medicines, juniper berries and the seeds of the tree of Abraham are harmful to the stomach. Know that all laxatives and everything that causes disgust are bad for the stomach; Coitus is one of the most harmful things for the stomach, and refusal of it is one of the most beneficial things for it. Violent vomiting, although useful in cleansing, does great harm by weakening the stomach.