February 7th, 2010
We have already learned that there are two most common types of irritable bowel syndrome: constipation predominant and diarrhea predominant. Let’s speak about those two in more detail.
Constipation is the condition in which defecation is delayed for a variety of reasons. It may be due to consciously ignoring or preventing defecation or to decreased colonic motility, which most commonly is secondary to aging, emotion, or a low-bulk diet. Bulk refers to the content of cellulose or other undigested materials in the diet, the volume of which is not decreased by absorption. The longer fecal material remains in the large intestine, the more water is reabsorbed, and the harder and drier the feces become, making defecation more difficult and sometimes painful. During this period additional material from the small intestine continues to enter the colon, progressively increasing the volume of its contents.
Many people have a mistaken belief that unless there is a bowel movement every day retention of fecal material and bacteria in the large intestine will somehow poison the body because of toxic products produced by the bacteria. Attempts to isolate such toxic agents from intestinal bacteria have been totally unsuccessful. In unusual cases where defecation has been prevented for a year or more by blockage of the rectum no ill effects from accumulated feces were noted except for the discomfort of carrying around the extra weight of 50 to 100 lb of feces retained in the large intestine. The symptoms of nausea, headache, loss of appetite, and general feeling of discomfort sometimes accompanying constipation appear to come from the distension of the rectum and large intestine. Experimentally inflating a balloon in the rectum of a normal individual produces similar sensations. Thus, there is no physiological necessity for having bowel movements regulated by a clock; whatever maintains a person in a comfortable state is physiologically adequate, whether this means a bowel movement after every meal, or once a day, or once a week.
Cathartics, or laxatives, are sometimes necessary to relieve constipation. Several types are in common use. Cellulose in vegetable matter is a natural cathartic because of its ability to increase intestinal motility by providing bulk which stretches the smooth muscle of the intestinal wall, increasing its sensitivity to the basic electrical rhythm, and thus increasing its contractile activity. Castor oil acts by irritating the smooth muscle of the intestinal tract, increasing its motility. Some cathartics, such as mineral oil, act by lubricating hard, dry fecal material, thus easing defecation. Such agents as milk of magnesia are not absorbed or absorbed only slowly by the intestinal wall; the presence of nonabsorbable solute causes water to be retained in the intestinal tract and along with the increased motility resulting from the in-creased volume helps to flush out the large intestine.
Diarrhea, the opposite of constipation, is characterized by frequent defecation, usually of highly fluid fecal matter. A primary cause is greater intestinal motility with less time for absorption and thus the delivery of a large volume of fluid to the large intestine overloading its capacity to absorb salt and water. Certain foods, such as prunes, stimulate intestinal motility and tend to produce diarrhea. Disease-producing bacteria often irritate the intestinal wall, increase motility of the intestinal tract, and lead to diarrhea. Prolonged diarrhea can result in a serious loss of fluid and salt, especially potassium, from the body as well as upsetting the acid-base balance of the body due to loss of bicarbonate.
February 5th, 2010
In order to understand the etiology of irritable bowel syndrome (IBS) one needs to learn more about the functioning of the colon.
The colon (large intestine), a tube about 2.5 in. in diameter, forms the last 4 ft of the gastrointestinal tract. The cecum forms a blind-ended pouch below the junction of the small and large intestines. The appendix, a small fingerlike projection from the end of the cecum, has no known function. The colon is not coiled but consists of three relatively straight segments, the ascending, transverse, and descending portions. The terminal portion of the descending colon is S-shaped, forming the sigmoid colon, which empties into a short section of tubing, the rectum. Although the large intestine has a greater diameter than the small intestine and is about half as long, its epithelial surface area is only about 1/30 that of the small intestine because the mucosa of the large intestine lacks villi and is not convoluted. The large intestine secretes no digestive enzymes and is responsible for the absorption of only about 4 percent of the total intestinal contents per day. Its primary function is to store and concentrate fecal material prior to defecation.
Chyme enters the colon through the ileocecal sphincter separating the ileum from the colon. This sphincter is normally closed, but after a meal when the gastroileal reflex increases the contractile activity of the ileum, the sphincter relaxes each time the terminal portion! of the ileum contracts, allowing chyme to enter the large intestine. Distension of the colon, on the other hand, produces a reflexive contraction of the sphincter, preventing further material from entering.
About 500 ml of chyme from the small intestine enters the colon each day. Most of this material is derived frame the secretions of the small intestine, since most of the ingested food has been absorbed before reaching the large intestine. The secretions of the colon are very scanty and consist mostly of mucus.
The primary absorptive process in the large intestine is the active transport of sodium from the lumen to blood with the accompanying osmotic reabsorption of water. If fecal material remains in the large intestine for a long time, almost all the water is reabsorbed, leaving behind dry fecal pellets. The cells lining the large intestine are unable to actively transport either glucose or аmino acids. There is a small net leakage of potassium into the colon, and severe depletion of total body potassium can occur as a result of repeated enemas and diarrhea.
The large intestine also absorbs some of the products synthesized by the bacteria in it. For example, small amounts of vitamins are synthesized by intestinal bacteria and absorbed into the body. Although this source of vitamins generally provides only a small part of the normal vitamin requirement per day, it may make a significant contribution when dietary intake of vitamins is low. The intestinal bacteria digest cellulose and utilize the glucose released for their own growth and reproduction.
Other bacterial products contribute to the production of intestinal gas (flatus). This gas is a mixture of nitrogen and carbon dioxide with small amounts of the inflammable gases hydrogen, methane, and hydrogen sul-fide. Bacterial fermentation produces gas in the colon at the rate of about 400 to 700 ml/day. In the cow, where bacterial fermentation makes a major contribution to the digestive process, as much as 300 to 600 liters of flatus may be produced each day.
The longitudinal smooth muscle in the human colon is incomplete, and the walls of the large intestine are folded into sacs called haustra by the contraction of the circular smooth muscle. Contractions of the circular smooth muscle produce a segmentation motion which is not propulsive. This movement is considerably slower than in the small intestine, and a contraction may occur only once every 30 min. Because of this slow movement, material entering the colon from the small intestine remains for 18 to 24 hr. Bacteria have time to grow and accumulate in the large intestine because of its slow movements; in the small intestine they do not have sufficient time to accumulate before being swept into the large intestine. During sleep and most of the day there is generally little or no movement in the large intestine, but three to four times a day, generally after meals, a marked increase in motility occurs. This usually coincides with the gastroileal reflex, described earlier, and probably has similar reflex mechanisms. This increased motility may lead to the phenomenon known as mass movement, in which large segments of the ascending and transverse colon contract simultaneously, propelling fecal material one-third to three-fourths of the length of the colon in a few seconds.
June 18th, 2009
There are several types of irritable bowel syndrome (IBS). The most common of them are constipation and diarrhea predominant types.
Constipation is usually the result of a diet low in fibre and high in processed foods. It can cause headaches, fatigue, bad breath and poor skin. Although many people go without passing a stool for several days, it really is best for your body to have a bowel movement at least once a day, so that toxins are not sitting around for too long. In peak bowel health, it takes about 8-12 hours for food to be fully digested, nutrients absorbed and for waste to be passed out.
Fibre-rich foods, such as raw fruit and vegetables, brown bread and wholegrains, can make an enormous difference to your regularity, but so too can juices, even though they do not contain much fibre. All fresh juices have an excellent cleansing effect on the gui and bowel and have a gentle laxative effect. The dark green juices, such as kale, spinach, and watercress can be particularly useful (they are rich in minerals and the В complex group of vitamins), as can the fruit juices pear, papaya, grape, and watermelon (which ali have a cleansing effect).
Food poisoning, stress and viruses can all cause diarrhea, which can also go hand in hand with uncomfortable stomach gripes. Anyone suffering from it should drink plenty of liquids, including some mild fresh juices, diluted with water. Varieties that can help settle a disturbed digestive system are apple, carrot and pineapple, best drunk on their own and diluted.
Diarrhea interspersed with constipation are the classic symptoms of irritable bowel syndrome, which can be brought on by stress, as well as other causes. Mild, yet nutritious juices {containing В vitamins and vitamin C) may help settle the stomach and bring a little relief. It is best not to overwhelm the stomach with combination juices, and the juices should be diluted before drinking.
1 apple
4fl oz/115ml still water
or
1 pear
4fl oz/115ml still water
or
l 1/2 carrots
4fl oz/115ml still water
or
2 stalks celery
4fl oz/ll5ml still water
Each juice recipe makes approximately one 8fl oz/230ml glass of juice. Juice each ingredient then blend using a spoon. And have a good luck with your IBS.
