The digestive system is made up of the alimentary canal and includes the mouth and salivary glands, the esophagus, stomach, liver, gallbladder, pancreas, small intestine, and large intestine. #
Its prime function is to digest food, absorb nutrients and eliminate waste through the bowel. Imbalances in the digestive system often affect the circulatory system as unwanted toxins are absorbed and bowel elimination is slowed. The names for the herbal combinations are chosen based on the properties of the key herbs in the formula.
Digestion – Herbal medicine is uniquely suited for the treatment of digestive system illnesses. Throughout medicine, ensuring that the healing properties of the herbs we consume have a direct effect on the lining of the alimentary canal. Herbs affect digestive system function not only through absorption and metabolism of the whole range of plant chemicals, but also through direct actions upon the tissue of the gut.
Much of the digestive system illness in our society is due simply to abuse. Today's average diet contains a preponderance of overly processed food and has a high content of chemical additives. The gastrointestinal tract is subject to direct chemical irritation from alcohol, carbonated drinks, and tobacco. In this context, it is easy to see why herbal remedies can be so helpful in treating the various inflammations and reactions that plague abusers. The direct soothing action of demulcents, healing properties of astringents, and general toning of bitters has much to offer in reversing such damage.
However, as with all true healing, any potential “cure” lies beyond the range of medicines, whether herbal or synthetic. The healing process must incorporate lifestyle changes to eliminate dietary indiscretions and chemical abuses as well as reduce stress. Herbal medicine can bring about dramatic improvements in even profound digestive system problems, but the potential to maintain these benefits long term lies in the hands of the person seeking treatment.
Used within such a broad context, herbal medicine offers specific remedies for particular pathological syndromes as well as tonics and normalizers that can help prevent problems from manifesting in the first place. It is possible to treat these problems within a context of general nurturing that speeds improvement and helps reestablish health and harmony. In the hands of a skilled phytotherapist, much can be achieved therapeutically. While the array of factors will be different for each individual with, for example, a gastric ulcer, it is possible to identify some general herbal guidelines.
Of all herbal traditions, that of using herbs to aid digestion has remained the most prominent in the memory of modern Europe. Whether culinary herbs such as rosemary or medicinal liqueurs like vermouth and chartreuse, therapeutic remedies are used in large quantities. The very name vermouth comes from the bitter herb wormwood. Herbs maintain their foothold in official pharmacopoeias as major therapeutic agents, in the form of digestive bitters, carminatives, and laxatives of varying strengths.
The ideal is to preserve health and maintain wellness, rather than merely treat illness. Of course, there is much more to preventive medicine than consuming medicinal substances, whether medicinal plants or chemical drugs. We can help out this in perspective by recalling the World Health Organization (WHO) definition of health:
Health is a state of complete physical, emotional, mental, and social wellbeing and not merely the absence of disease or infirmity.
—Overview— Digestion is the breaking down of chemicals in the body, into a form that can be absorbed. #
It is also the process by which the body breaks down chemicals into smaller components that can be absorbed by the blood stream. In mammals, preparation for digestion begins with the cephalic phase in which saliva is produced in the mouth and digestive enzymes are produced in the stomach. Mechanical and chemical digestion begins in the mouth where food is chewed and mixed with saliva to break down starches. The stomach continues to break food down mechanically and chemically through the churning of the stomach and mixing with enzymes. Absorption occurs in the stomach and gastrointestinal tract, and the process finishes with defecation.
—Phases of gastric secretion—
Cephalic phase – This phase occurs before food enters the stomach and involves preparation of the body for eating and digestion. Sight and thought stimulate the cerebral cortex. Taste and smell stimulus is sent to the hypothalamus and medulla oblongata. After this it is routed through the vagus nerve and release of acetylcholine. Gastric secretion at this phase rises to 40% of maximum rate. Acidity in the stomach is not buffered by food at this point and thus acts to inhibit parietal (secretes acid) and G cell (secretes gastrin) activity via D cell secretion of somatostatin.
Gastric phase – This phase takes 3 to 4 hours. It is stimulated by distention of the stomach, presence of food in stomach and increase in ph. Distention activates long and myenteric reflexes. This activates the release of acetylcholine which stimulates the release of more gastric juices. As protein enters the stomach, it binds to hydrogen ions, which raises the pH of the stomach to around pH 6. Inhibition of gastrin and HCl secretion is lifted. This triggers G cells to release gastrin, which in turn stimulates parietal cells to secrete HCI. HCl release is also triggered by acetylcholine and histamine.
Intestinal phase – This phase has 2 parts, the excitatory and the inhibitory. Partially digested food fills the duodenum. This triggers intestinal gastrin to be released. Enterogastric reflex inhibits vagal nuclei, activating sympathetic fibers causing the pyloric sphincter to tighten to prevent more food from entering, and inhibits local reflexes.
—Oral cavity— In humans, digestion begins in the oral cavity where food is chewed. Saliva is secreted in large amounts (1-1.5 liters/day) by three pairs of exocrine salivary glands (parotid, submandibular, and sublingual) in the oral cavity, and is mixed with the chewed food by the tongue. There are two types of saliva. One is a thin, watery secretion, and its purpose is to wet the food. The other is a thick, mucous secretion, and it acts as a lubricant and causes food particles to stick together and form a bolus. The saliva serves to clean the oral cavity and moisten the food, and contains digestive enzymes such as salivary amylase, which aids in the chemical breakdown of polysaccharides such as starch into disaccharides such as maltose. It also contains mucin, a glycoprotein which helps soften the food into a bolus.
Swallowing transports, the chewed food into the esophagus, passing through the oropharynx and hypopharynx. The mechanism for swallowing is coordinated by the swallowing center in the medulla oblongata and pons. The reflex is initiated by touch receptors in the pharynx as the bolus of food is pushed to the back of the mouth.
—Esophagus— The esophagus is a narrow muscular tube about 25 centimeters long which starts at pharynx at the back of the mouth, passes through the thorax and thoracic diaphragm, and ends at the cardiac orifice of the stomach. The wall of the esophagus is made up of two layers of smooth muscles, which form a continuous layer from the esophagus to the stomach and contract slowly, over long periods of time. The inner layer of muscles is arranged circularly in a series of descending rings, while the outer layer is arranged longitudinally. At the top of the esophagus, is a flap of tissue called the epiglottis that closes during swallowing to prevent food from entering the trachea (windpipe). The chewed food is pushed down the esophagus to the stomach through peristaltic contraction of these muscles. It takes only about seven seconds for food to pass through the esophagus and no digestion takes place.
—Stomach— The stomach is a small, ‘C'-shaped pouch with walls made of thick, elastic muscles, which stores and helps break down food. Food enters the stomach through the cardiac orifice where it is further broken apart and thoroughly mixed with gastric acid, pepsin, and other digestive enzymes to break down proteins. The acid itself does not break down food molecules; rather it provides an optimum pH for the reaction of the enzyme pepsin and kills many microorganisms that are ingested with the food. The parietal cells of the stomach also secrete a glycoprotein called intrinsic factor which enables the absorption of vitamin B-12. Other small molecules such as alcohol are absorbed in the stomach, passing through the membrane of the stomach, and entering the circulatory system directly. Food in the stomach is in semi-liquid form.
The transverse section of the alimentary canal reveals four distinct and well-developed layers within the stomach:
Serous membrane, a thin layer of mesothelial cells that is the outermost wall of the stomach.
Muscular coat, a well-developed layer of muscles used to mix ingested food, composed of three sets running in three different alignments. The outermost layer runs parallel to the vertical axis of the stomach (from top to bottom), the middle is concentric to the axis (horizontally circling the stomach cavity) and the innermost oblique layer, which is responsible for mixing and breaking down ingested food, runs diagonal to the longitudinal axis. The inner layer is unique to the stomach; all other parts of the digestive tract have only the first two layers.
Submucosa composed of connective tissue that links the inner muscular layer to the mucosa and contains the nerves, blood, and lymph vessels.
Mucosa is the extensively folded innermost layer filled with connective tissue and covered in gastric glands that may be simple or branched tubular, and secret mucus, hydrochloric acid, pepsinogen, and renin. The mucus lubricates the food and prevents hydrochloric acid from acting on the walls of the stomach.
—Small intestine— After being processed in the stomach, food is passed to the small intestine via the pyloric sphincter. The majority of digestion and absorption occurs here after the milky chyme enters the duodenum. Here it is further mixed with three different liquids:
Bile, which emulsifies fats to allow absorption, neutralizes the chyme and is used to excrete waste products such as bilin and bile acids.
Pancreatic juice made by the pancreas.
Intestinal enzymes of the alkaline mucosal membranes. The enzymes include maltase, lactase and sucrase (all three of which process only sugars), trypsin and chymotrypsin.
As the pH level changes in the small intestines and gradually becomes basic, more enzymes are activated further that chemically break down various nutrients into smaller molecules to allow absorption into the circulatory or lymphatic systems. Small, finger-like structures called villi, each of which is covered with even smaller hair-like structures called microvilli improve the absorption of nutrients by increasing the surface area of the intestine and enhancing speed at which nutrients are absorbed. Blood containing the absorbed nutrients is carried away from the small intestine via the hepatic portal vein and goes to the liver for filtering, removal of toxins, and nutrient processing.
The small intestine and remainder of the digestive tract undergoes peristalsis to transport food from the stomach to the rectum and allow food to be mixed with the digestive juices and absorbed. The circular muscles and longitudinal muscles are antagonistic muscles, with one contracting as the other relaxes. When the circular muscles contract, the lumen becomes narrower and longer and the food is squeezed and pushed forward. When the longitudinal muscles contract, the circular muscles relax, and the gut dilates to become wider and shorter to allow food to enter.
—Large intestine— After the food has been passed through the small intestine, the food enters the large intestine. The large intestine is roughly 1.5 meters long, with three parts: the cecum at the junction with the small intestine, the colon, and the rectum. The colon itself has four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon. The large intestine absorbs water from the bolus and stores feces until it can be egested. Food products that cannot go through the villi, such as cellulose (dietary fiber), are mixed with other waste products from the body and become hard and concentrated feces. The feces is stored in the rectum for a certain period and then the stored feces is egested due to the contraction and relaxation through the anus. The exit of this waste material is regulated by the anal sphincter.
—Fat digestion— The presence of fat in the small intestine produces hormones which stimulate the release of lipase from the pancreas and bile from the gallbladder. The lipase (activated by acid) breaks down the fat into monoglycerides and fatty acids. The bile emulsifies the fatty acids so they may be easily absorbed.
Short and some medium chain fatty acids are absorbed directly into the blood via intestine capillaries and travel through the portal vein just as other absorbed nutrients do. However, long chain fatty acids and some medium chain fatty acids are too large to be directly released into the tiny intestinal capillaries. Instead, they are absorbed into the fatty walls of the intestine villi and reassembled again into triglycerides. The triglycerides are coated with cholesterol and protein (protein coat) into a compound called a chylomicron.
Within the villi, the chylomicron enters a lymphatic capillary called a lacteal, which merges into larger lymphatic vessels. It is transported via the lymphatic system and the thoracic duct up to a location near the heart (where the arteries and veins are larger). The thoracic duct empties the chylomicrons into the bloodstream via the left subclavian vein. At this point the chylomicrons can transport the triglycerides to where they are needed.
—Digestive hormones— There are at least four hormones that aid and regulate the digestive system:
Gastrin – is in the stomach and stimulates the gastric glands to secrete pepsinogen (an inactive form of the enzyme pepsin) and hydrochloric acid. Secretion of gastrin is stimulated by food arriving in stomach. The secretion is inhibited by low pH.
Secretin – is in the duodenum and signals the secretion of sodium bicarbonate in the pancreas and it stimulates the bile secretion in the liver. This hormone responds to the acidity of the chyme.
Cholecystokinin (CCK) – is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gallbladder. This hormone is secreted in response to fat in chyme.
Gastric inhibitory peptide (GIP) – is in the duodenum and decreases the stomach churning in turn slowing the emptying in the stomach. Another function is to induce insulin secretion.
—Significance of pH in digestion— Digestion is a complex process which is controlled by several factors. pH plays a crucial role in a normally functioning digestive tract. In the mouth, pharynx, and esophagus, pH is typically about 6.8, very weakly acidic. Saliva controls pH in this region of the digestive tract. Salivary amylase is contained in saliva and starts the breakdown of carbohydrates into monosaccharides. Most digestive enzymes are sensitive to pH and will not function in a low-pH environment like the stomach. A pH below 7 indicates an acid, while a pH above 7 indicates a base; the concentration of the acid or base, however, does also play a role.
pH in the stomach is very acidic and inhibits the breakdown of carbohydrates while there. The strong acid content of the stomach provides two benefits, both serving to denature proteins for further digestion in the small intestines, as well as providing non-specific immunity, retarding, or eliminating various pathogens.
In the small intestines, the duodenum provides critical pH balancing to activate digestive enzymes. The liver secretes bile into the duodenum to neutralize the acidic conditions from the stomach. Also, the pancreatic duct empties into the duodenum, adding bicarbonate to neutralize the acidic chyme, thus creating a neutral environment. The mucosal tissue of the small intestines is alkaline, creating a pH of about 8.5, thus enabling absorption in a mild alkaline in the environment.
—Herbs and Good Diet— By far the most important contribution made by plants to the health of the human digestive system is in the quality of the foods we eat. Often the only real difference between a salad vegetable and a medicinal herb is that one tastes better! The body requires more than 40 nutrients for energy, growth, and tissue maintenance. All of these are found in a well-rounded diet, and many of them are found both in medicinal herbs and in plants eaten as grains, vegetable, or fruits.
—Water— As the most plentiful component in the body, water is also crucial to survival. It is the medium for bodily fluids such as blood and lymph, in which forms it transports nutrients into cells and carries out waste products and toxins.
—Carbohydrate— Carbohydrates, proteins, and fats—a group of dietary components known as macronutrients—provide fuel in the form of calories. Carbohydrates, the body's main energy source, can be divided into two types. Simple carbohydrates are sugars; complex carbohydrates into starches, such as those found in potatoes and bread.
—Proteins— Proteins support issue growth and repair and help produce antibodies, hormones, and enzymes, which are essential for all chemical reactions in the body. Dietary protein sources include meat, fish, dairy products, poultry, dried beans, nuts, and eggs.
—Fats— Dietary fat protects internal organs, provides energy, insulates against cold, and helps the body absorb certain vitamins. There are three kinds of fats. Saturated fats are found in meat, dairy products, and coconut oil. Mono-unsaturated fats occur in olive, peanut, and canola oils; polyunsaturated fats are found in corn, cottonseed, safflower, soy and sunflower oils.
A very important group of polyunsaturated fats are the essential fatty acids (EFAs) known as arachidonic acid, linolenic acid is the basis of the omega-3 EFAs. They are essential to the human diet because they cannot be synthesized in the body from other nutrients. Essential fatty acids are necessary for the formation of healthy cell membranes, the proper development and functioning of the brain and nervous system, and the production of the eicosanoids (thromboxanes, leukotrienes, and prostaglandins).
Linoleic acid is found primarily in seeds, nuts, grains, and legumes. Alph-linolenic acid is found in green leaves, phytoplankton and algae, and selected seeds, nuts, and legumes. Arachidonic acid is obtained from meat, and the important omega-3 EFA eicosapentaenoic acid is found in fish.
—Therapies for Relieving Excess— Constipation is the most prevalent excess condition of the digestive system found in modern societies. The ingestion of large quantities of refined foods is the prime cause of this condition and results in unwanted toxins being absorbed into the circulatory system and elimination of waste being slowed.
Excess conditions in the digestive system are often marked by patterns of minor aches, pains and ailments including: flatulence, abdominal pains, anxiety, nervousness, selfishness, difficulty rising form bed, constipation, nausea, abdominal bloating, obesity, diarrhea, anemia, motions sickness, indigestion, headache and vomiting. If left unchecked, these ailments may develop into illnesses such as: diverticulosis, constipation, arthritis, gastric ulcers, obesity, anorexia, neuromuscular disorders, and yeast infections.
Early herbal therapies for these conditions consisted of single herbs like cascara Sagrada bark which is a laxative Cascara is not simply a laxative however, and with time and experience, herbalist recognized and recorded in their herbals the several properties of cascara. The British Herbal Pharmacopoeia lists cascara as a laxative, Cholagogue and mild purgative.
These lists of empirical properties of an herb are the key to understanding herbal combinations. Herbalists have found that they can enhance a particular property of a single herb by adding herbs that complement and support a given property. Conversely, the herbalist is also able to minimize an unwanted property by adding herbs that counteract to balance that property.
—Therapies for Supplementing Deficient Conditions— Weakened conditions of the digestive system can result from poor blood circulation, inefficient function of the digestive organs, lifestyle, or aging. Herbalists use aromatic herbs to stimulate blood flow and increase the production of digestive fluids and enzymes. Mucilaginous herbs are also employed to soothe inflamed tissues and provide bulk to the stool.
Weakened conditions of the digestive system are often associated with patterns of minor aches, pains, and ailments including: diarrhea, hemorrhoids, hernia, joint pains, muscle cramps, cold hands and feet, lack of muscle tone, easy bruising, sinus congestion, vaginal discharge, indigestion, anemia and weight loss. If left unchecked, these ailments may develop into illnesses including: gastric ulcers, colitis, chronic enteritis, prolapse of organs, chronic diarrhea, and Crohn's disease.
Early herbal therapies for these conditions consisted of single herbs like slippery elm bark which soothes inflamed tissues and absorbs toxins from the bowel. Slippery elm is not simply a demulcent however, and with time and experience, herbalists recognized and recorded in their herbals the several properties of slippery elm. The British Herbal Pharmacopoeia lists slippery elm as a demulcent, emollient, nutrient and antitussive.
—Reference– Wikipedia.org
—References— “Nutritional Herbology” A Reference Guide to Herbs By – Mark Pedersen ISBN: 1-885653-07-7 Copyright 2008
—References— Kimball's Biology Pages, Digestion
—References— Chemistry lecture
—References— American Journal of Physiology, article
—References— “Medical Herbalism” The Science and Practice of Herbal Medicine David Hoffmann, FNIMH, AHG ISBN: 0-89281-749-6 Copyright 2003
—References—
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Generated on December 15, 2008
Updated on October 14, 2009
