The Healthy Gut Cookbook: How to Keep in Excellent Digestive Health with 60 Recipes and Nutrition Advice. Marguerite Patten

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СКАЧАТЬ a healthy person, the contents from a meal take between 15 and 18 hours to pass from one end of the digestive tube to the other. Three to five hours are spent in the stomach, and about four hours in the small intestine where absorption of nutrients takes place.

      

      Digestion begins in the mouth, where food is crushed and ground by the teeth and mixed with saliva containing enzymes that start breaking down starchy foods into simple sugars. Proper chewing is important. Food needs to be properly shredded to give maximum exposure to digestive enzymes, and saliva needs a chance to be mixed into the mass of food. After being swallowed, food is carried by muscular waves down the oesophagus and emptied into the stomach. A muscular valve (rather like a rubber band) prevents food and stomach fluid returning up the oesophagus.

      The stomach is a large muscular pouch, or bulge, in the gut where food is thoroughly mixed and kneaded. Little is absorbed in the stomach other than certain drugs and alcohol. The lining in this part of the digestive tube contains two types of specialized cells: one secretes powerful hydrochloric acid needed to liquefy the food, and the other produces thick mucus needed to protect the lining of the stomach from its own acid. If the mucous barrier breaks down, ulcers can develop. Despite its acidic environment, the stomach can be infected with a bacterium, Helicobacter pylori, which is present in the majority of ulcer patients. (Ulcer treatment now includes antibiotics that eliminate this unwelcome intruder and speed healing.) From the stomach, the products of digestion pass through another rubber-band-like constriction (the pyloric valve) at the bottom of the stomach and enter the most important part of the digestive system: the small intestine.

      The small intestine is about 7.5 metres (25 feet) in length and has three distinguishable parts: the duodenum (separated from the stomach by the pyloric valve), the jejunum and the ileum. Each is modified to perform a specific biochemical process. The first step must be to neutralize the digestive material coming from the stomach to make it slightly alkaline. This occurs in the duodenum, where bile manufactured by the liver and stored in the gall bladder joins alkaline fluids from the pancreas (needed to break down fats) and flows into the gut through a delicate structure called the common bile duct. (The pancreas also produces insulin needed to control blood sugar levels, but that hormone is transferred directly from the pancreas into the bloodstream.) By this time, the environment of the gut is watery. Pancreatic enzymes continue working as the digestive matter enters the jejunum, where enzymes produced by cells in the gut wall complete the breakdown of carbohydrates into sugars, fats into fatty acids and glycerol, and proteins into amino acids. Along the way vitamins, minerals and other compounds are released from the digested remains of food. The breakdown of food into its useful parts is called digestion.

      Millions of finger-like villi rise out of the intestinal wall and are washed by the nutrient slurry passing through. Each is covered by a thin membrane of cells encasing a twist of blood capillaries so small that red blood cells flow through single file. Individual molecules of protein (amino acids), sugar, vitamins and minerals pass easily from the slurry into the bloodstream, which carries them to the liver for further processing within the body (metabolism). This passage is the normal case, and is called absorption. If villi are damaged by illness or poor diet, they tend to lie flat, thus hindering absorption. (Some fats are absorbed in a slightly different manner by the lymphatic system, a vast circulatory system of tiny tubes and glands involved in fighting infection and controlling fluid within the body.) By the time the food residue reaches the third part of the small intestine (ileum), it is fully digested. Nutrients are absorbed here, as are bile salts, which are returned to the liver. Unfortunately, toxic substances are also absorbed by the gut; these are passed to the liver for detoxification or storage.

      Finally, the digested material reaches the large intestine (colon, anus and rectum). It enters the colon as a wet bulky mass consisting mainly of fibre (see here for information about fibre). This part of the gut has modified villi that absorb water and leave the faeces or stool (bowel motion). But the colon contains something more: it contains millions – perhaps billions – of bacteria that help this final stage of digestion by breaking down fibre. (More is said about gut bacteria under the section on Probiotics in the next chapter.)

      Like all other good ‘systems’, the digestive system is no better than any one of its parts. For example, at the start of the digestive tube, teeth are used to tear and crush food to facilitate its chemical breakdown in the stomach and gut. If food is not crushed and mixed properly – perhaps because of ill-fitting false teeth, or a rushed meal eaten under stress – the chemical processes that occur further along the tube will be less effective. If the chemical processes are less than effective, absorption of nutrients will be incomplete. When nutrients do not reach the body in quantities needed to keep tissues healthy because of a failure in the digestive process, a potentially dangerous condition called malabsorption occurs.

absorption and malabsorption

      A fully functioning digestive system is needed to reap maximum benefit from a healthy diet. As noted above, the normal flow of nutrients from the gut into the body through the bloodstream is called absorption. When this process fails, malabsorption results. If malabsorption becomes severe, malnutrition sets in. Malnutrition destroys the body. It lowers resistance to infection, stunts physical and mental growth in children, causes infertility, and is to blame for the slow degeneration of bones, muscles and other organs. Many scientists believe that borderline nutritional deficiencies (in which the body receives smaller quantities of vital nutrients than are required by normal body functions) are at the root of heart disease, arthritis and possibly certain forms of cancer.

      Symptoms of malabsorption are variable and may include weight loss, fatigue and foul-smelling, bulky diarrhoea. If untreated, malabsorption leads to illnesses as diverse as peripheral nerve damage and anaemia. Causes of malabsorption usually involve inflammation of the gut and include food sensitivities, Coeliac disease, Crohn’s disease, chronic pancreatitis, advanced diabetes mellitus and cystic fibrosis. Left untreated, parasitic infection of the gut can also block the passage of nutrients.

      There is evidence that a genetic factor contributes to the development of illnesses leading to malabsorption.

love your liver!

      The largest organ in your body – the liver – deserves special attention. Protected by the ribs and tucked under the diaphragm, it contributes to the metabolism of fats and proteins, helps maintain normal blood sugar levels, is responsible for the formation and storage of energy as glycogen, and secretes bile to aid the digestion of fat. Of equal importance to its various roles in metabolism, the liver is the body’s great detoxifier. It neutralizes alcohol, nicotine, drugs and poisons, and stores toxic substances that have no means of being excreted from the body. It is responsible for at least 22 chemical functions on which life depends.

      

      You obviously need your liver, but how do you care for it? Unlike the muscular parts of the digestive system, which quickly let us know when something is wrong, the liver is a quiet organ that gives little trouble unless it has suffered serious damage. Here are some basic tips.

      

      • Avoid recreational drugs!

      • Avoid heavy drinking and excessive intake of spicy foods.

      • Restrict intake of saturated fats from dairy products СКАЧАТЬ