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Dietary Fiber

Dietary fiber

Dietary fibers are the indigestible portion of plant foods that move food through the digestive system and absorb water.

Uses

There are two principal types of dietary fiber: soluble and insoluble. Insoluble fiber is simply bulk that changes little as it passes through the body. Soluble fiber, on the other hand, forms a soft gel in solution with water. Most foods provide a mixture of both, but are listed as mostly one or the other. Soluble fiber has been shown to be able to bind bile salts which may reduce blood cholesterol levels. It also may slow the absorption of glucose from the intestine, thereby requiring less insulin secretion. Fiber may decrease spasms in the gastrointestinal tract by keeping the lumen distended. The main value of dietary fiber is that it provides bulk to the bolus moving through the digestive tract. There are two great advantages to this: by bulking up the bolus, eventually increasing the weight of the stool, it's easier for the digestive system to move it through, and the bulkier stool also tends to retain normal amounts of moisture to make it easier to eliminate with less straining and abrasion. The moisture content of human stool does not change when more fiber is consumed, except marginally from psyllium husk (Eastwood et. al & Prynne et. al). Because the bowel regulation is mostly due to bulking and not to increased water in the stool, it is very unlikely to cause diarrhea unless if taken in massive amounts (this is as long as one does not consider synthetic sugars in this category). Increased fiber consumption appears to lower the risk of developing type II diabetes, heart disease, diverticulitis, and colon cancer. [http://www.hsph.harvard.edu/nutritionsource/fiber.html] It may also help prevent high cholesterol and help fight obesity. High-fiber foods help move waste through the digestive tract faster and easier, so possibly harmful substances do not have as much contact with the gastrointestinal tract and reduce straining. Many cause blood sugar or cholesterol absorption to decrease in amplitude of the plotted absorption or decrease the amount absorbed by slowing or decreasing the absorption.

Harmful effects

An overdose of soluble fiber can cause diarrhea and worsen irritable bowel syndrome. Negative effects of dietary fiber include a reduced absorption of vitamins, minerals, proteins, and calories from the gut. Some insoluble fibers can bind to certain minerals: calcium, magnesium, phosphorus, and iron. This is unlikely to be harmful in the average adult, but guidelines for the US have been established, and fiber users are advised to avoid taking a fiber supplement with or close to (in time) vitamin or mineral supplements. The American Dietetic Association (ADA) recommends 20-35 g/day for a healthy adult depending on calorie intake (e.g., a 2000 cal/8400 kj diet should include 25 g of fiber per day). The ADA's recommendation for a child was that intake should equal their age in years plus 5 g/day for children (example a 4 year old should consume 9 g/day). No guidelines have yet been established for the elderly or very ill. Patients with current constipation, vomiting, and abdominal pain should see a physician. Certain bulking agents are not commonly recommended with the prescription of opioids because the slow transit time mixed with larger stools may lead to severe constipation, pain, or obstruction.

Sources of fiber

Current recommendations suggest that adults consume 20-35 grams of dietary fiber per day, but the average American's daily intake of dietary fiber is only 14-15 grams. [http://www.hsph.harvard.edu/nutritionsource/fiber.html] The ADA recommends trying to get most of your dietary fiber from foods you eat, as an important part of consuming variety, nutrition, synergy between nutrients, and possibly phytonutrients. Soluble fiber is found in many foods, including:
- legumes, (peas, soybeans, and other beans)
- oats
- some fruits (particularly apples, bananas), and berries
- certain vegetables, such as broccoli and carrots
- psyllium seed. Legumes also typically contain shorter-chain carbohydrates that are indigestible by the human digestive tract but which are digested by bacteria in the small intestine, which is a cause of flatulence. Sources of insoluble fiber include
- whole grain foods
- bran
- nuts and seeds
- vegetables such as green beans, cauliflower, zucchini, celery
- the skins of some fruits, including tomatoes
- root vegetables, such as potatoes and yams, including the skins

Fiber supplements

There are many types of soluble fiber supplements available to consumers for nutritional purposes, for the treatment of various gastrointestinal disorders, and for such possible health benefits as lowering cholesterol levels, reducing the risk of colon cancer, or losing weight.

Psyllium husk

Psyllium husk (best known under the brand Metamucil from Proctor & Gamble), but also available generically) is a good source of both soluble and insoluble fiber. It is low in calories, is available in powders and in capsules, and must be taken with water to avoid a risk of choking. Psyllium husk may reduce the risk of heart disease by lowering cholesterol levels, and is known to help alleviate the symptoms of irritable bowel syndrome. Psyllium husk is considered a "bulk-forming laxative." Because bacteria that occur naturally in the intestinal tract can digest the fiber in psyllium husk and cause it to ferment, psyllium husk fiber supplements can cause gas. The FDA allows foods containing 0.75 g or 1.7 g of psyllium husk fiber or oat fiber to claim that they may be able to reduce the risk of heart disease (J Am Diet Assoc 2002).

Methylcellulose

Methylcellulose is created from the cell wall of plants. Sold as a powder, it is undigestible, unfermentable, and doesn't have calories that humans can use. Citrucel (by GlaxoSmithKline) is one popular brand of methylcellulose.

Polycarbophil

Polycarbophil is also plant based and is similar to methylcellulose. It causes less bloating than psyllium husk and is effective for treating constipation, but is not as effective in treating IBS. Polycarbophil is found in a large number of consumer brands, including Wyeth Corporation's Fibercon. It is considered a "bulk-forming laxative."

Vegetable gums

Vegetable gum fiber supplements are relatively new to the market. Sold as a powder, vegetable gum fibers dissolve easily with no aftertaste. They are not effective for the treatment of IBS. The most popular brand of vegetable gum fiber is Benefiber, made by Novartis.

References

- Mayo Clinic Health Letter , March 1998, copyrighted material
- Donatelle, Rebecca J. Health: The Basics. 6th ed. San Francisco: Pearson Education, Inc. 2005.
- [http://www.about.com About.com FAQ, copyrighted material]
- [http://www.eatright.org ADA website]
- [http://www.eatright.org ADA position paper - J Am Diet Assoc 2002;102:993-1000, copyrighted material]

External links

- [http://www.highfiberdiet.net Database of Fiber-Containing Foods]
- [http://www.althealth.co.uk/services/info/ailments/diverticulitis1.php Alternative health site - Fiber & Diverticulosis]
- [http://www.eatright.org ADA Position paper - J Am Diet Assoc 2002;102:993-1000] Category:Nutrition Category:Dietary supplements ja:食物繊維

Gel

:In optical filters and theatrical lighting a color gel is a transparent or translucent colored panel used to change the color of transmitted light. A gel (from the lat. gelu—freezing, cold, ice or gelatus—frozen, immobile) is an apparently solid, jellylike material formed from a colloidal solution. By weight, gels are mostly liquid, yet they behave like solids. An example is gelatin. Many gels display thixotropy - they become fluid when agitated, but resolidify when resting. By replacing the liquid with gas it is possible to prepare aerogels, materials with exceptional properties like very low density, very high surface area, and excellent thermal insulation properties. In 2005 a sound induced gelation effect was demonstrated.

Applications

Many substances can form gels when a suitable thickener or gelling agent is added to their formula. This approach is common in manufacture of wide range of products, from foods to paints, adhesives. In fiber-optic communications, a gel resembling petroleum jelly in viscosity is used to surround a fiber, or multiple fibers, enclosed in a loose buffer tube. This gel serves to lubricate and support the fibers in the buffer tube. It also prevents water intrusion if the buffer tube is breached. Gels are also used in fiber-optics as index-matching materials. Source: from Federal Standard 1037C and from the FAA Glossary of Optical Communications Terms

Bile salts

Bile (or gall) is a bitter, greenish-yellow alkaline fluid secreted by the liver of most vertebrates. In many species, it is stored in the gallbladder between meals and upon eating is discharged into the duodenum where it aids the process of digestion.

Physiology

Bile salts are steroid compounds (deoxycholic and cholic acid), often conjugated with glycine and taurine, and act to some extent as a detergent, helping to emulsify fats (increasing surface area to help enzyme action), and thus aid in their absorption in the small intestine. The most important compounds are the salts of taurocholic acid and deoxycholic acid. Bile salts combine with phospholipids to break down fat globules in the process of emulsification. Emulsified droplets then are organized into many micelles which increases absorption. Besides its digestive function, bile serves as the route of excretion for the hemoglobin breakdown product (bilirubin) which gives bile its colour. Bile also contains cholesterol, which occasionally accretes into lumps in the gall bladder, forming gallstones. In species with a gall bladder (humans and most domestic animals except horses and rats), further modification of bile occurs in that organ. The gall bladder stores and concentrates bile during the fasting state. Typically, bile is concentrated five-fold in the gall bladder by absorption of water and small electrolytes - virtually all of the organic molecules are retained. The human liver produces about a quart (or litre) of bile per day. 95% of secreted bile salts are reabsorbed in the terminal ileum and re-used. Since bile increases the absorption of fats, it is an important part of the absorption of the fat-soluble vitamins: A, D, E, and K. Bile from slaughtered animals can be mixed with soap. This mixture, applied to textiles a few hours before washing, is a traditional and rather effective method for removing various kinds of tough stains.

Four humours

Yellow bile and black bile were two of the four vital fluids or humours of ancient and medieval medicine; for example, melancholia was believed to be caused by a bodily surplus of black bile. Yellow bile is sometimes called ichor.

Cholesterol

Cholesterol is a steroid, a lipid, and an alcohol, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. Most cholesterol is not dietary in origin, it is synthesized internally. Cholesterol is present in higher concentrations in tissues which either produce more or have more densely-packed membranes, for example, the liver, spinal cord, brain and atheroma. Cholesterol plays a central role in many biochemical processes, but is best known for the association of cardiovascular disease with various lipoprotein cholesterol transport patterns in the blood.

History of the name

The name originates from the Greek chole- (bile) and stereos (solid), as researchers first identified cholesterol (C27H45OH ) in solid form in gallstones.

Physiology

Synthesis and intake

gallstoneCholesterol is primarily synthesized from acetyl CoA through the HMG-CoA reductase pathway in many cells/tissues. About 20–25% of total daily production (~1 g/day) occurs in the liver; other sites of higher synthesis rates include the intestines, adrenal glands and reproductive organs. For a person of about 150 pounds (68 kg), typical total body content is about 35 g, typical daily internal production is about 1 g and typical daily dietary intake is 200 to 300 mg. Of the 1,200 to 1,300 mg input to the intestines (via bile production and food intake), about 50% is reabsorbed into the bloodstream.

Properties

Cholesterol is minimally soluble in water; it cannot dissolve and travel in the water-based bloodstream. Instead, it is transported in the bloodstream by lipoproteins - protein "molecular-suitcases" that are water-soluble and carry cholesterol and fats internally. The proteins forming the surface of the given lipoprotein particle determine from what cells cholesterol will be removed and to where it will be supplied. The largest lipoproteins, which primarily transport fats from the intestinal mucosa to the liver, are called chylomicrons. They carry mostly triglyceride fats and cholesterol (that from food and especially internal cholesterol secreted by the liver into the bile). In the liver, chylomicron particles give up triglycerides and some cholesterol, and are converted into low-density lipoprotein (LDL) particles, which carry triglycerides and cholesterol on to other body cells. In healthy individuals the LDL particles are large and relatively few in number. In contrast, large numbers of small LDL particles are strongly associated with promoting atheromatous disease within the arteries. (Lack of information on LDL particle number and size is one of the major problems of conventional lipid tests.) High-density lipoprotein (HDL) particles transport cholesterol back to the liver for excretion, but vary considerably in their effectiveness for doing this. Having large numbers of large HDL particles correlates with better health outcomes. In contrast, having small amounts of large HDL particles is strongly associated with atheromatous disease progression within the arteries. (Note that the concentration of total HDL does not indicate the actual number of functional large HDL particles, another of the major problems of conventional lipid tests.) The cholesterol molecules present in LDL cholesterol and HDL cholesterol are identical. The difference between the two types of cholesterol derives from the carrier protein molecules; the lipoprotein component.

Regulation

Biosynthesis of cholesterol is directly regulated by the cholesterol levels present, though the homeostatic mechanisms involved are only partly understood. A higher intake in food leads to a net decrease in endogenous production and vice versa. The main regulatory mechanism is the sensing of intracellular cholesterol in the endoplasmic reticulum by the protein SREBP (Sterol Regulatory Element Binding Protein 1 and 2). In the presence of cholesterol, SREBP is bound to two other proteins: SCAP (SREBP-cleavage activating protein) and Insig-1. When cholesterol levels fall, Insig-1 dissociates from the SREBP-SCAP complex, allowing the complex to migrate to the Golgi apparatus, where SREBP is cleaved by S1P and S2P (site 1/2 protease), two enzymes that are activated by SCAP when cholesterol levels are low. The cleaved SREBP then migrates to the nucleus and acts as a transcription factor to bind to the "Sterol Regulatory Element" of a number of genes to stimulate their transcription. Among the genes transcribed are the LDL receptor and HMG-CoA reductase. The former scavenges circulating LDL from the bloodstream, whereas HMG-CoA reductase leads to an increase of endogenous production of cholesterol. A large part of this mechanism was clarified by Dr Michael S. Brown and Dr Joseph L. Goldstein in the 1970s. They received the Nobel Prize in Physiology or Medicine for their work in 1985. The average amount of blood cholesterol varies with age, typically rising gradually until one is about 60 years old. A study by Ockene et al. showed that there are seasonal variations in cholesterol levels in humans, more, on average, in winter.

Function

Cholesterol is an important component of the membranes of cells, providing stability; it makes the membrane's fluidity stable over a bigger temperature interval. The hydroxyl group on cholesterol interacts with the phosphate head of the membrane, and the bulky steroid and the hydrocarbon chain is embedded in the membrane. It is the major precursor for the synthesis of vitamin D, of the various steroid hormones, including cortisol, cortisone, and aldosterone in the adrenal glands, and of the sex hormones progesterone, estrogen, and testosterone. The presence of cholesterol has a direct effect on the fluidity of the membrane. Further recent research shows that cholesterol has an important role for the brain synapses as well as in the immune system, including protecting against cancer.

Excretion

Cholesterol is excreted from the liver in bile and reabsorbed from the intestines. Under certain circumstances, when more concentrated, as in the gallbladder, it crystallises and is the major constituent of most gallstones, although lecithin and bilirubin gallstones also occur less frequently.

Role in atheromatous disease

See also the main article hypercholesterolemia In conditions with elevated concentrations of LDL particles, especially small LDL particles, cholesterol promotes atheroma plaque deposits in the walls of arteries, a condition known as atherosclerosis, which is a major contributor to coronary heart disease and other forms of cardiovascular disease. (In contrast, HDL particles have been the only identified mechanism by which cholesterol can be removed from atheroma. Increased concentrations of large HDL particles, not total HDL particles, correlate with lower rates of atheroma progressions, even regression.) There is a world-wide trend to believe that lower total cholesterol levels tend to correlate with lower atherosclerosis event rates. However, the primary association of atherosclerosis with cholesterol has always been specifically with cholesterol transport patterns, not total cholesterol per se. For example, total cholesterol can be low, yet made up primarily of small LDL and small HDL particles and atheroma growth rates are high. In contrast, however, if LDL particle number is low (mostly large particles) and a large percentage of the HDL particles are large (HDL is actively reverse transporting cholesterol), then atheroma growth rates are usually low, even negative, for any given total cholesterol concentration. Multiple human trials utilizing HMG-CoA reductase inhibitors or statins, have repeatedly confirmed that changing lipoprotein transport patterns from unhealthy to healthier patterns significantly lower cardiovascular disease event rates, even for people with cholesterol values currently considered low for adults; However, no statistically significant mortality benefit has been derived to date by lowering cholesterol using medications in asymptomatic people, i.e., no heart disease, no history of heart attack, etc. Some of the better recent randomized human outcome trials studying patients with coronary artery disease or its risk equivalents include the Heart Protection Study (HPS), the PROVE IT trial, and the TNT trial. In addition, there are trials that have looked at the effect of lowering LDL as well as raising HDL and atheroma burden using intravascular ultrasound. Small trials have shown prevention of progression of coronary artery disease and possibly a slight reduction in atheroma burden with successful treatment of an abnormal lipid profile. The [http://www.americanheart.org/cholesterol/about.jsp American Heart Association] provides a set of guidelines for total (fasting) blood cholesterol levels and risk for heart disease: However, as today's testing methods determine LDL ("bad") and HDL ("good") cholesterol separately, this simplistic view has become somewhat outdated. The desirable LDL level is considered to be less than 100 mg/dl (2.6 mmol/L), although a newer target of <70 mg/dl can be considered in higher risk individuals based on some of the above-mentioned trials. A ratio of total cholesterol to HDL —another useful measure— of far less than 5:1 is thought to be healthier. Of note, typical LDL values for children before fatty streaks begin to develop is 35 mg/dl. Patients should be aware that most testing methods for LDL do not actually measure LDL in their blood, much less particle size. For cost reasons, LDL values have long been estimated using the formula: Total-cholesterol − total-HDL − 20% of the triglyceride value = estimated LDL. Increasing clinical evidence has strongly supported the greater predictive value of more-sophisticated testing that directly measures both LDL and HDL particle concentrations and size, as opposed to the more usual estimates/measures of the total cholesterol carried within LDL particles or the total HDL concentration. There are three commercial labs in the United States that offer more-sophisticated analysis using different methodologies. As outlined above, the real key is cholesterol transport, which is determined by both the proteins that form the lipoprotein particles and the proteins on cell surfaces with which they interact.

Cholesteric liquid crystals

Some cholesterol derivatives, (among others simple cholesteric lipids) are known to generate liquid crystalline phase called cholesteric. The cholesteric phase is in fact a chiral nematic phase, and changes colour when its temperature changes. Therefore, cholesterol derivatives are commonly used as temperature-sensitive dyes, in liquid crystal thermometers, and in temperature-sensitive paints.

Sources

- Anderson RG. Joe Goldstein and Mike Brown: from cholesterol homeostasis to new paradigms in membrane biology. Trends Cell Biol 2003:13:534-9. PMID 14507481.
- Ockene IS, Chiriboga DE, Stanek EJ 3rd, Harmatz MG, Nicolosi R, Saperia G, Well AD, Freedson P, Merriam PA, Reed G, Ma Y, Matthews CE, Hebert JR. Seasonal variation in serum cholesterol levels: treatment implications and possible mechanisms. Arch Intern Med 2004;164:863-70. PMID 15111372.

External links

- [http://www.nhlbi.nih.gov/guidelines/cholesterol/ Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults ] US National Institutes of Health Adult Treatment Panel III
- [http://www.fao.org/docrep/V4700E/V4700E08.htm Aspects of fat digestion and metabolism - UN/WHO Report 1994]
- [http://www.americanheart.org/cholesterol/about.jsp American Heart Association]
- [http://www.davoslife.com/pdf/Cholesterol%20Article1%20link.pdf A review of scientific studies on the cholesterol lowering potential of tocotrienols in comparison with statins]
- [http://www.westonaprice.org/moderndiseases/benefits_cholest.html The Weston A. Price Foundation] is a group that questions the connection between cholesterol and atheroma.
- [http://www.cholesterol-and-health.com Cholesterol and Health] (alternative views on cholesterol's relationship to disease)
- [http://www.ravnskov.nu/myth1.htm The Cholesterol Myths] Uffe Ravnskov, M.D., Ph.D. Category:Steroids Category:Nutrition ja:コレステロール th:คอเลสเตอรอล

Glucose

Glucose (Glc), a monosaccharide, is one of the most important carbohydrates. The cell uses it as a source of energy and metabolic intermediate. Glc is one of the main products of photosynthesis and starts cellular respiration. The natural form (D-glucose) is also referred to as dextrose, especially in the food industry. This article deals with the D-form of Glc (see Isomers-section bellow)

Structure

cellular respiration cellular respiration Glc contains six carbon atoms and an aldehyde group and is therefore refered to as an aldohexose. Glc molecule can exist in an open-chain (acyclic) and ring (cyclic) form, the latter being the result of a intramolecular reaction between the aldehyde C atom and the C-5 hydroxyl group to form an intramolecular hemiacetal. In water solution both forms are in equilibrium, and at pH 7 the cyclic one is the predominant. As the ring contains 5 carbon and one oxygen atoms, which resembles the structure of pyran, the cyclic form of Glc is also refered to as glucopyranose. In this ring, each carbon is linked to hydroxyl side group with the exception of the fifth atom, which links to a sixth carbon atom outside the ring, forming a CH₂OH group.

Isomers

Glc has 4 optic centers which means that in theory Glc can have 15 optical stereoisomers. In living organisms only 7 of them are found, of which Gal and Man are the most important. These eight isomers (including Glc) are all diastereoisomers in relation to each other and all belong to the [http://en.wikipedia.org/wiki/Monosaccharide#Isomerism D-series]. An additional asymetric center at C-1 (called the anomeric carbon atom) is created when Glc cyclizes and two ring structures, called anomers, can be formed - α-Glc and β-Glc. They structurally differ in the orientation of the hydroxyl group linked to C-1 in the ring. When D-Glc is drawn as a Haworth_projection, the designation α means that the hydroxyl group attached to C-1 is bellow the plane of the ring, β means - it is above. The α and β forms interconvert over a timescale of hours in aqueous solution, to a final stable ratio of α:β 36:64, in a process called mutarotation. mutarotation.]]

Production

Natural

#Glucose is one of the products of photosynthesis in plants and some prokaryotes. #In animals and fungi, glucose is the result of the breakdown of glycogen, a process known as glycogenolysis. In plants - the breakdown substrate is starch. #In animals, glucose is synthesized in the liver and kidneys from non-carbohydrate intermediates, such as pyruvate and glycerol, by a process known as gluconeogenesis.

Commercial

Glc is produced commercially via the enzymatic hydrolysis of starch. Many crops can be used as the source of starch Maize, rice, wheat, potato, cassava, arrowroot, and sago are all used in various parts of the world. In the United States, cornstarch (from maize) is used almost exclusively. This enzymatic process has two stages. Over the course of 1-2 hours near 100 °C, these enzymes hydrolyze starch into smaller carbohydrates containing on average 5-10 Glc units each. Some variations on this process briefly heat the starch mixture to 130 °C or hotter one or more times. This heat treatment improves the solubility of starch in water, but deactivates the enzyme, and fresh enzyme must be added to the mixture after each heating. In the second step, saccharification, the partially hydrolyzed starch is completely hydrolyzed to Glc using the glucoamylase enzyme from the fungus Aspergillus niger. Typical reaction conditions are pH 4.0–4.5, 60 °C, and a carbohydrate concentration of 30–35% by weight. Under these conditions, starch can be converted to Glc at 96% yield after 1–4 days. Still higher yields can be obtained using more dilute solutions, but this approach requires larger reactors and processing a greater volume of water, and is not generally economical. The resulting glucose solution is then purified by filtration and concentrated in a multiple-effect evaporator. Solid D-Glc is then produced by repeated crystallizations.

Function

We can speculate on the reasons why Glc, and not another monosaccharide such as Fru, is so widely used. Glc can form from formaldehyde under abiotic conditions, so it may well have been available to primitive biochemical systems. Probably more important to advanced life is the low tendency of Glc, by comparison to other hexose sugars, to nonspecifically react with the amino groups of proteins. This reaction (glycosylation) reduces or destroys the function of many enzymes. The low rate of glycosylation is due to Glc's preference for the less reactive cyclic isomer. Nevertheless, many of the long-term complications of diabetes (e.g., blindness, kidney failure, and peripheral neuropathy) are probably due to the glycosylation of proteins.

As an energy source

Glc is a ubiquitous fuel in biology. Carbohydrates are the human body's key source of energy, providing 4 calories (17 kilojoules) of food energy per gram. Breakdown of carbohydrates (e.g. starch) yields mono- and disaccharides, most of which is Glc. Through glycolysis and later in the reactions of TCAC, Glc is oxidized to eventually form CO₂ and water, yielding energy, mostly in the form of ATP.

As a precursor

Glc is critical in the production of protein and in lipid metabolism.

Glc is used as a precursor for the synthesis of several important substances. Starch, cellulose, and glycogen ("animal starch") are common Glc polymers (polysaccharides). Lactose - the milk sugar, is a Glc-Gal disaccharide. In sucrose, another important disaccharyde, Glc is joined to Fru.

Sources and absorbtion

All major dietary carbohydrates contain Glc, either as their only building block, as in starch and glycogen, or together with another monosaccharide, as in sucrose and lactose. In the lumen of the duodenum and small intestine the oligo- and polysaccharides are broken down to monosaccharides by the pancreatic and intestinal glycosidases. Glc is then transported across the enterocytes and into the bloodstream, first at the apical membrane by Na⁺-dependent transporter protein (GLUT2) and then at the basal membrane by a totally different protein. Some of Glc goes directly to fuel brain cells and erythrocytes, while the rest makes its way to the liver and muscles, where it is stored as glycogen, and to fat cells, where it is stored as fat. Glycogen is the body's auxiliary energy source, tapped and converted back into Glc when there is needs for energy.

External links

- (D-glucose)
- (L-glucose)
- (D-glucose)
- (L-glucose)
- [http://www.evowiki.org/index.php/Glucose More on the chemistry and function of glucose in biology at EvoWiki]
- [http://www.compchemwiki.org/index.php?title=Glucose Computational Chemistry Wiki] Category:Chemical pathology Category:Monosaccharides Category:Nutrition Category:Sweeteners ko:포도당 ja:グルコース

Lumen

Lumen can mean:
- lumen (unit), the SI unit of luminous flux
- 141 Lumen, an asteroid discovered by the French astronomer Paul Henry in 1875
- lumen (anatomy), the cavity or channel within a tubular structure, such as the vascular lumen of a blood vessel or the lumen of a seminiferous tubule : See also: Lux.

Colon distention

Colon distention is enlargement of the splenic flexure which is beyond the limits of normal colonic distention.

Stool

A stool can refer to:
- A type of chair
- Feces Category:Disambiguation

Moisture

Moisture generally refers to the presence of water in trace amounts. It is found in several different forms, which can cause rot in wood or other organic material, corrosion in metals, and electrical short circuits.

Abrasion

In dermatology, an abrasion is superficial damage to the skin, generally not deeper than the epidermis. It is more superficial than an excoriation, although it can give mild bleeding. Mild abrasions do not scar, but deep abrasions may lead to the development of scarring tissue. Bandage using non-stick padding, as blood will attach to the bandage, resulting in extreme pain and suffering.

Geographical

Abrasion - A river carries with it particles of sand and silt and moves pebbles and boulders at the time of high flow. This material rubs against the bed and banks of the river and wears them away.
river

Diverticulitis

Diverticulitis is a common disease of the bowel, in particular the large intestine. Diverticulitis develops from diverticulosis, which involves the formation of pouches (diverticula) on the outside of the colon. Diverticulitis results if one of these diverticulum becomes inflamed. In complicated diverticulitis, bacteria may subsequently infect the outside of the colon if an inflamed diverticulum bursts open. If the infection spreads to the lining of the abdominal cavity, (peritoneum), this can cause a potentially fatal peritonitis. Sometimes inflamed diverticula can cause narrowing of the bowel, leading to an obstruction. Also, the affected part of the colon could adhere to the bladder or other organ in the pelvic area, causing a fistula, or abnormal communication between the colon and an adjacent organ. Diverticulitis most often affects middle-aged and elderly persons, though it can strike younger patients as well.

Incidence

In Western countries, diverticular disease most commonly involves the sigmoid colon (95% of patients). The prevalence of diverticular disease has increased from an estimated 10% in the 1920s to between 35 and 50% by the late 1960s. 65% of those currently 85 years of age and older can be expected to have some form of diverticular disease of the colon. Less than 5% of those aged 40 years and younger may also be affected by diverticular disease. Left-sided diverticular disease (involving the sigmoid colon) is most common in the West, while right-sided diverticular disease is more prevalent in Asia and Africa. Among patients with diverticulosis, 10-25% patients will go on to develop diverticulitis within their lifetimes.

Causes

The development of colonic diverticulum is thought to be a result of raised intraluminal colonic pressures. The sigmoid colon has the smallest diameter of any portion of the colon, and therefore the portion which would be expected to have the highest intraluminal pressure according to the laws of Laplace. The postulate that low dietary fiber, particularly non-soluble fiber (also known in older parlance as "roughage") predisposes individuals to diverticular disease is supported within the medical literature. It is thought that mechanical blockage of a diverticulum, possibly by a piece of feces, leads to infection of the diverticulum.

Presentation

Patients often present with the classic triad of left lower quadrant pain, fever, and leukocytosis (an elevation of the white cell count in blood tests). Patients may also complain of nausea or diarrhea; others may be constipated. Less commonly, an individual with diverticulitis may present with right-sided abdominal pain. This may be due to the less prevalent right-sided diverticula or a very redundant sigmoid colon.

Diagnosis

The differential diagnosis includes colon cancer, inflammatory bowel disease, ischemic colitis, and irritable bowel syndrome, as well as a number of urological and gynecological processes. Some patients report bleeding from the rectum. In today's world of modern medicine, patients with the above symptoms are commonly studied with a computed tomography, or CT scan. The CT scan is very sensitive (98%) in diagnosing diverticulitis. It may also identify patients with more complicated diverticulitis, such as those with an associated abscess. CT also allows for radiologically guided drainage of associated abscesses, possibly sparing a patient from immediate surgical intervention. Other studies, such as barium enema and colonoscopy are contraindicated in the acute phase of diverticulitis due to the risk of perforation.

Treatment

An initial episode of acute diverticulitis is usually treated with conservative medical management, including bowel rest (ie, nothing by mouth), IV fluid resuscitation, and broad-spectrum antibiotics which cover anaerobic bacteria and gram-negative rods. However, recurring acute attacks or complications, such as peritonitis, abscess, or fistula may require surgery, either immediately or on an elective basis. Upon discharge patients are placed on a high-fiber diet. There is some evidence this lowers the recurrence rate.

Complications

- obstruction
- peritonitis
- abscess
- fistula
- bleeding
- strictures Category:Surgery Category:Gastroenterology

Obesity

Obesity is a condition where the natural energy reserve, stored in the fatty tissue of humans and mammals is increased to the point where it may impair health. Obesity in wild animals is relatively rare, but it is common in domestic animals like pigs and household pets who may be overfed and underexercised. In humans it is generally considered to be a leading cause of health problems. Excessive body weight has been shown to predispose to various forms of disease, particularly cardiovascular disease. Interventions, such as weight loss and medication, are frequently recommended to reduce the risk of developing disease. Additionally, many people undertake weight loss regimens for health and aesthetic reasons. medication

Definition

Obesity is a concept that is being continually redefined. In humans, the most common statistical estimate of obesity is the body mass index (BMI), calculated by dividing the weight by the height squared; its unit is therefore kg/m², although no actual surface is implied. The BMI was created in the 19th century by the Belgian statistician Adolphe Quetelet. Interpretation of the BMI:
- A person with a BMI over 25.0 kg/m² is considered overweight.
- A BMI over 30.0 kg/m² denotes obesity.
- A further threshold at 35.0 kg/m² is identified as urgent morbidity risk (morbid obesity). Adolphe Quetelet The American Institute for Cancer Research considers a BMI between 18.5 and 25 to be an ideal target for a healthy individual (although several sources consider a person with a BMI of less than 20 to be underweight). The cut-off points between categories are occasionally redefined, and may indeed differ from country to country. In June 1998 the National Institutes of Health brought official U.S. category definitions into line with those used by the WHO, moving the American "overweight" threshold from BMI 27 to BMI 25. About 30,000,000 Americans moved from "ideal" weight to being 1–10 pounds (0.5–5 kg) "overweight". In 2000, WHO was advised to consider lowering the BMI threshold for overweight in Asians from BMI 25 to BMI 23, and for obesity in Asians from BMI 30 to BMI 25, due to epidemiological studies indicating that Asians suffer a greater number of obesity-related conditions at lower BMI; however, to date, WHO has not made any changes in recommendations. In addition, some clinicians suggest raising the BMI thresholds for those of African, African-American, and Polynesian descent because members of these groups have a greater ratio of lean body mass to fat at all body weights; the proposed thresholds for these groups are BMI 26 for overweight, and BMI 32 for obesity. To date, no major professional or medical organization has officially adopted this suggestion. In the future, a healthy BMI for a given individual may be defined to some extent by his ethnic or racial origin. As a result of this somewhat arbitrary process, the BMI cannot offer a complete diagnosis, in that it ignores fat distribution within the body (see central obesity), and the relative fat-muscle-bone contributions to total body weight. A powerful athlete may be classified as obese by the BMI due to heavy musculature, while a false-normal may be diagnosed in the case of an elderly person with very low lean mass, which masks excess adiposity. On its own, a BMI score is therefore inadequate as a diagnostic tool. In practice, in most examples of overweightness that may be harmful to health, both doctor and patient can see "by eye" that fat is an issue. In these cases, BMI thresholds provide simple targets all patients can understand. Doctors may also use a simple measure of waist circumference (which is a better predictor of complications such insulin resistance due to visceral fat); the skinfold test, in which a pinch of skin is precisely measured to determine the thickness of the subcutaneous fat layer; or bioelectrical impedance analysis, usually only carried out at specialist clinics. Such clinical data is rarely available in the statistical raw materials required for large public health studies, however — whereas height and weight is commonly recorded. For this essential reason, BMI remains the most commonly-used approach for public health studies, and the most useful for cross-border, longitudinal, and other types of comparative analysis.

Etymology

Obesity is the nominal form of obese which comes from the Latin obēsus, which means "stout, fat, or plump." Ēsus is the past participle of edere (to eat), with ob added to it. In Classical Latin, this verb is seen only in past participial form. Its first attested usage in English was in 1651, in N. Biggs' Matæotechnia Medicinæ Praxeuus.

Cultural and social significance

Culture and obesity

1651 In several human cultures, obesity is associated with attractiveness, strength, and fertility. Some of the earliest known cultural artifacts, known as Venuses, are pocket-sized statuettes representing an obese female figure. Although their cultural significance is unrecorded, their widespread use throughout pre-historic Mediterranean and European cultures suggests a central role for the obese female form in magical rituals, and implies cultural approval of (and perhaps reverence for) this body form. In comparison to Western Culture, the young and slender woman is seen and desired by both men and women. It can be seen as more important for women than men. "Although the female body is predisposed to proportionately more fat and the male to more muscle, the plump or stout woman's body is considered neither beautiful nor sexually attractive." Obesity functions as a symbol of wealth and success in cultures prone to food scarcity. Well into the early modern period in European cultures, it still served this role. But as food security was realised, it came to serve more as a visible signifier of "lust for life", appetite, and immersion in the realm of the erotic. This was especially the case in the visual arts, such as the paintings of Rubens (1577–1640), whose regular use of the full female figures gives us the description Rubenesque for plumpness. Obesity can also be seen as symbol for a system of prestige. "The kind of food, the quantity, and the manner in which it is served are among the important criteria of social class. In most tribal societies, even those with a highly stratified social system, everyone - royalty and the commoners - ate the same kind of food, and if there was famine everyone was hungry. With the ever increasing diversity of foods, food has become not only a matter of social status, but also a mark of one's personality and taste." Contemporary cultures which approve of obesity, to a greater or lesser degree, include African, Arabic, Indian, and Pacific Island cultures. In Western cultures, obesity has come to be seen more as a medical condition than as a social statement. In American culture, many use a popular snap, "Yo' momma's so fat...", in playing "the dozens". A small minority of activists, especially clustered around the tradition of feminism, seek through the fat acceptance movement to challenge that emerging consensus. There are some who are trying to combat the problem of obesity. In American society, "we have indicated a number of strong trends in our culture which run counter to obesity. The desire for health, for longevity, for youthfulness, for sexual attractiveness is indeed a powerful motivation."

Popular culture

fat acceptance movement Various stereotypes of obese people have found their way into expressions of popular culture. A common stereotype is the obese character who has a warm and dependable personality, presumedly in compensation for social exclusion, but equally common is the obese vicious bully. Gluttony and obesity are commonly depicted together in works of fiction. In cartoons, obesity is used to comedic effect, with fat cartoon characters having to squeeze through narrow spaces, frequently getting stuck. It can be argued that depiction in popular culture adds to and maintains commonly perceived stereotypes, in turn harming self esteem of obese people. A charge of discrimination on the basis of appearance could be leveled against these depictions. On the other hand, obesity is often associated with positive characteristics such as good humor (the stereotype of the jolly fat man like Santa Claus), and some people are more sexually attracted to obese people than to slender people (see chubby culture, fat admirer).

Causes

Causative factors

Obesity is believed to be caused by excessive caloric intake accompanied with insufficient caloric expenditure. Factors that may contribute to this imbalance include:
- Limited exercise and sedentary lifestyle
- Genetic predisposition
- A high glycemic diet (i.e. a diet that consists of meals that give high postprandial blood sugar)
- Weight cycling, caused by repeated attempts to lose weight by dieting
- Underlying illness (e.g. hypothyroidism)
- An eating disorder (such as binge eating disorder)
- Stressful mentality
- Insufficient sleeping
- Psychotropic medications As with many medical conditions, obesity often develops from a combination of genetic and environmental factors. Polymorphisms in various genes controlling appetite, rate of metabolism, and adipokine release predispose to obesity, but the condition, to some extent, requires availability of sufficient calories and/or limited exercise, and possibly other factors, to develop fully. Various genetic abnormalities that predispose to obesity have been identified (such as Prader-Willi syndrome and leptin receptor mutations), but these are absent in most people with obesity. It is presumed that a large proportion of the causative genes are still to be identified. Some eating disorders can lead to obesity, especially binge eating disorder (BED). As the name indicates, patients with this disorder are prone to overeat, often in binges. A proposed mechanism is that the eating serves to reduce anxiety, and some parallels with substance abuse can be drawn. An important additional factor is that BED patients often lack the ability to recognize hunger and satisfaction, something that is normally learned in childhood. Learning theory suggests that early childhood conceptions may lead to an association between food and a calm mental state.

Evolutionary aspects

Although there is no definitive explanation for the recent increase of obesity, the evolutionary hypothesis comes closest to providing some understanding of this phenomenon. In times when food was scarce, the ability to take advantage of rare periods of abundance and use such abundance by storing energy efficiently was undoubtedly an evolutionary advantage. This is precisely the opposite of what is required in a sedentary society, where high-energy food is available in abundant quantities in the context of decreased exercise. Although many people may have a genetic propensity towards obesity, it is only with the reduction in physical activity and a move towards high-calorie diets of modern society that it has become widespread.

Neurobiological mechanisms

evolution Flier summarizes the many possible pathophysiological mechanisms involved in the development and maintenance of obesity. This field of research had been almost unapproached until leptin was discovered in 1994. Since this discovery, many other hormonal mechanisms have been proposed that participate in the regulation of appetite and food intake, storage patterns of adipose tissue, development of insulin resistance, and possible ways of interfering with these mechanisms. Since leptin's discovery, ghrelin, orexin, PYY 3-36, cholecystokinin, adiponectin, and numerous other mediators have been studied. The adipokines are mediators produced by adipose tissue; their action is thought to modify many obesity-related diseases. Leptin and ghrelin are considered to be complementary in their influence on appetite, with the stomach producing ghrelin when relatively empty and leptin being produced by adipose tissue when satiated with nutrients. Resistance to the leptin signal and causes for this resistance have been implicated in dysregulation of appetite, although administration of leptin has not proven to be a feasible way of suppressing appetite in humans. Neuroscientific approaches hinge on the action of the aforementioned hormones and mediators on the hypothalamus, the part of the brain that is thought to produce hunger signals for higher centers and induce food intake behavior. Lesion studies in the 1940s and 1950s identified two regions of the hypothalamus — the lateral hypothalamus (LH) and ventromedial hypothalamus (VMH) — as the brain's hunger and satiety centers, respectively. Specific lesions to a mouse's LH suppressed its appetite while damaging the VMH caused overeating. Studies of the distribution of the leptin receptor in the mid-1990s cast doubt upon this dual center theory of hunger and satiety. Leptin's effect on the arcuate nucleus melanocortin system is now considered central to the regulation of feeding and metabolism.

Societal causes

While it may often be obvious why a certain individual gets fat, it is far more difficult to understand why the average weight of certain societies have recently been growing. While genetic causes are central to who is obese, they cannot explain why one culture grows fatter than another. This is most notable in the United States. In the years from just after the Second World War until 1960 the average person's weight increased, but few were obese. In 1960 almost the entire population was well fed, but not overweight. In the two and a half decades since 1980 the growth in the rate of obesity has accelerated markedly and is increasingly becoming a public health concern. There are a number of theories as to the cause of this change since 1980. Most believe it is a combination of various factors.
- Lack of activity: obese people appear to be less active in general than lean people, and not just because of their obesity. A controlled increase in calorie intake of lean people did not make them less active; correspondingly when obese people lost weight they did not become more active. Weight change does not affect activity levels, but the converse seems to be the case.
- One of the most important is the much lower relative cost of foodstuffs: massive changes in agricultural policy in the United States and Europe have led to food prices for consumers being lower than at any point in history. Sugar and corn syrup, two huge sources of food energy, are some of the most subsidized products by the United States government. This can raise costs for consumers in some areas but greatly lower it in others. Current debates into trade policy highlight disagreements on the effects of subsidies.
- Increased marketing has also played a role. In the early 1980s the Reagan administration lifted most regulations pertaining to advertising to children. As a result, the number of commercials seen by the average child increased greatly, and a large proportion of these were for fast food and candy.
- Changes in the price of mineral oil and petrol are also believed to have had an effect, as unlike during the 1970s it is now affordable in the United States to drive everywhere — at a time when public transit goes underused. At the same time more areas have been built without sidewalks and parks.
- The changing workforce as each year a greater percent of the population spends their entire workday behind a desk or computer, seeing virtually no exercise. In the kitchen the microwave oven has seen sales of unhealthy frozen convenience foods skyrocket and has encouraged more elaborate snacking.
- A social cause that is believed by many to play a role is the increasing number of two income households where one parent no longer remains home to look after the house. This increases the number of restaurant and take-out meals.
- Urban sprawl may be a factor: obesity rates increase as urban sprawl increases, possibly due to less walking and less time for cooking.
- Since 1980 both sit-in and fast food restaurants have seen dramatic growth in terms of the number of outlets and customers served. Low food costs, and intense competition for market share, led to increased portion sizes — for example, McDonalds french fries portions rose from 200 calories (840 kilojoules) in 1960 to over 600 calories (2,500 kJ) today.
- Increased food production is a likely factor. The U.S. produces three times more food than U.S. residents eat.
- Increasing affluence itself (including many of the above factors as accompaniments of affluence) may be a cause, or contributing factor since obesity tends to flourish as a disease of affluence in countries which are developing and becoming westernised [http://www.iotf.org/]. This is supported by a dip in American GDP after 1990, the year of the Gulf War, followed by an exponential increase. U.S. obesity statistics followed the same pattern, offset by two years [http://www.cdc.gov/brfss/].
- An ageing population may also be a major factor, as the likelihood of becoming obese increases with age. Beyond their twenties, the older a person becomes the slower their metabolism becomes, reducing the amount of calories required to sustain the body, thus if a person does not reduce their intake of food with age, they will become obese over time. As the average age of individuals within a society increases, the rate of obesity also increases. This situation is exacerbated by the baby boom generation, which represents a disproportionately large portion of the population in many countries and is currently nearing the latter end of the typical lifespan in affluent nations, and therefore is in the high-risk zone for obesity. Interestingly an increase in the number of Americans who exercise and diet occurred before the increase in obesity, and some scholars have even argued that these trends actually encouraged obesity. Nearly all diets fail, with participants resuming their previous eating habits or even engaging in binge eating. Many then see an overall increase in their weight. If the diet is then repeated and abandoned again, a pattern of rising and falling weight is established, known as weight cycling. Similarly those who work out but then stop can end up being heavier than those who never exercised.

Poverty link

Some obesity co-factors are resistant to the theory that the "epidemic" is a new phenomenon. In particular, a class co-factor consistently appears across many studies. Comparing net worth with BMI scores, a 2004 study found obese American subjects approximately half as wealthy as thin ones. When income differentials were factored out, the inequity persisted — thin subjects were inheriting more wealth than fat ones. Another study finds women who married into higher status predictably thinner than women who married into lower status.

Complications

Obesity, especially central obesity (male-type or waist-predomimant obesity), is an important risk factor for the "metabolic syndrome" ("syndrome X"), the clustering of a number of diseases and risk factors that heavily predispose for cardiovascular disease. These are diabetes mellitus type 2, high blood pressure, high blood cholesterol, and triglyceride levels (combined hyperlipidemia). An inflammatory state is present, which — together with the above — has been implicated in the high prevalence of atherosclerosis (fatty lumps in the arterial wall), and a prothrombotic state may further worsen cardiovascular risk. Apart from the metabolic syndrome, obesity is also correlated (in population studies) with a variety of other complications. For many of these complaints, it has not been clearly established to what extent they are caused directly by obesity itself, or have some other cause (such as limited exercise) that causes obesity as well. Most confidence in a direct cause is given to the mechanical complications in the following list, compiled by the American Medical Association for general physicians:
- Cardiovascular: congestive heart failure, enlarged heart and its associated arrhythmia and dizziness, cor pulmonale, varicose veins, and pulmonary embolism
- Endocrine: polycystic ovarian syndrome (PCOS), menstrual disorders, and infertility
- Gastrointestinal: gastroesophageal reflux disease (GERD), fatty liver disease, cholelithiasis (gallstones), hernia, and colorectal cancer
- Renal and genitourinary: urinary incontinence, glomerulopathy, hypogonadism (male), breast cancer (female), uterine cancer (female), stillbirth
- Integument (skin and appendages): stretch marks, acanthosis nigricans, lymphedema, cellulitis, carbuncles, intertrigo
- Musculoskeletal: hyperuricemia (which predisposes to gout), immobility, osteoarthritis, low back pain
- Neurologic: stroke, meralgia paresthetica, headache, carpal tunnel syndrome, dementia
- Respiratory: dyspnea, obstructive sleep apnea, hypoventilation syndrome, Pickwickian syndrome, asthma
- Psychological: Depression, low self esteem, body image disorder, social stigmatization While being severely obese has many health ramifications, those who are somewhat overweight face little increased mortality or morbidity. Some studies suggest that the somewhat "overweight" tend to live longer than those at their "ideal" weight[http://www.chron.com/cs/CDA/ssistory.mpl/nation/3142605]. This may in part be attributable to lower mortality rates in diseases where death is either caused or contributed to by significant weight loss due to the greater risk of being underweight experienced by those in the ideal category. Osteoporosis is known to occur less in slightly overweight people.

Therapy

The mainstay of treatment for obesity is an energy-limited diet and increased exercise. Although adherence to this regimen can cure obesity, many patients are unable to make the required sacrifices. In fact there are no studies showing that an energy restricted diet can lead to long term weight loss. It appears that the homeostatic mechanisms regulating body weight are very robust, thus impeding weight loss when attempted using calorie restriction. Recent scientific research has cast some doubt over whether or not dieting actually improves health, with some studies indicating that dieting may in fact be more detrimental than remaining overweight In a clinical practice guideline by the American College of Physicians, the following five recommendations are made: # People with a BMI of over 30 should be counseled on diet, exercise and other relevant behavioral interventions, and set a realistic goal for weight loss. # If these goals are not achieved, pharmacotherapy can be offered. The patient needs to be informed of the possibility of side-effects and the unavailability of long-term safety and efficacy data. # Drug therapy may consist of sibutramine, orlistat, phentermine, diethylpropion, fluoxetine, and bupropion. Evidence is not sufficient to recommend sertraline, topiramate, or zonisamide. # In patients with BMI > 40 who fail to achieve their weight loss goals (with or without medication) and who develop obesity-related complications, referral for bariatric surgery may be indicated. The patient needs to be aware of the potential complications. # Those requiring bariatric surgery should be referred to high-volume referral centers, as the evidence suggests that surgeons who perform these procedures frequently have fewer complications. Much research focuses on new drugs to combat obesity, which is seen as the biggest health problem facing developed countries. Nutritionists and many doctors feel that these research funds would be better devoted to advice on good nutrition, healthy eating, and promoting a more active lifestyle. Medication most commonly prescribed for diet/exercise-resistant obesity is orlistat (Xenical®, which reduces intestinal fat absorption by inhibiting pancreatic lipase) and sibutramine (Reductil®, Meridia®, an anorectic). In the presence of diabetes mellitus, there is evidence that the anti-diabetic drug metformin (Glucophage®) can assist in weight loss — rather than sulfonylurea derivatives and insulin, which often lead to further weight gain. The thiazolidinediones (rosiglitazone or pioglitazone) can cause slight weight gain, but decrease the "pathologic" form of abdominal fat, and are therefore often used in obese diabetics. Increasingly, bariatric surgery is being used to combat obesity. The most common weight loss surgery in Europe and Australia is the adjustable gastric band where a silicon ring is placed around the top of the stomach to help restrict the amount of food eaten in a sitting. This surgery has been FDA approved in the United States since 2001 but has been being used in other parts of the world since the early 1990s. It is considered the safest and least invasive of the available weight loss surgeries such as Roux-en-Y gastric bypass surgery (RNY), biliopancreatic diversion, and stomach stapling (also known as "vertical banded gastroplasty", VBG). Unlike those more invasive techniques the band surgery does not cut into or reroute any of the digestive tract and is completely reversible. Removing the implant returns the stomach to it's pre-surgical norm. All of these surgeries can be done laparoscopically. The more invasive of the surgeries usually bypass or remove some portion of the patient's intestines which causes malabsorption and dumping. All of these surgeries come with risk to the patient, from the LAP-BAND which has a mortality rate of 1 in 2000 to the RNY Bypass which has a mortality rate of 1 in 200. RNY surgery appears to be popular because the weight tends to come off faster than with the band but studies have shown that at 3-6 years out the amount of weight lost and the amount of loss maintained is nearly identical. Therefore the patient needs to consider the long term ramifications of their choice. None of these weight loss surgeries should be considered lightly and all risks must be examined and weighed against the risks of remaining obese. Bariatric surgery is not the easy way out, it requires the patient to make lifelong changes to their diet if they are to keep the lost weight off in the long term. Restrictive surgeries such as the adjustable gastric band offer the patient a built-in tool but it should be considered a tool not a magic solution. They can help a person to eat less but they cannot choose what the patient puts in their mouth, thus the need for long term commitments to eat properly.

Controversies

There is continuous debate over obesity, at several levels. While scientific evidence for particular risks and treatments is fairly firm, the evidence informing debates on exact causation, social impact and necessary policy responses is much less clear-cut. In the area of policy and public debate, statistics demonstrating correlations are typically misinterpreted as demonstrating causation, a fallacy known as the spurious relationship. As much of the data is open to interpretation, there have been many "experts" taking positions, as well as policy pressure groups, influencing the debate from various angles.

Medicalization of obesity

Controversy exists as to whether the concept of "obesity" is a valid one. Critics assert that physically active people are healthier than the sedentary regardless of their body weight. The focus on weight and body mass is fed, in their view, by a diet promotion industry, drug companies, and segments of the medical profession for profit purposes, by promoting a vision that equates health with slenderness, and makes extreme slenderness of a sort that is quite difficult for most people to achieve an ideal. In The Obesity Myth, Paul Campos writes that: :... (F)rom the perspective of a profit-maximising medical and pharmaceutical industry, the ideal disease would be one that never killed those who suffered from it, that could not be treated effectively, and that doctors and their patients would nevertheless insist on treating anyway. Luckily for it, the American health care industry has discovered (or rather invented) just such a disease. It is called "obesity". Basically, obesity research in America is funded by the diet and drug industry — that is, the economic actors who have the most to gain from the conclusion that being fat is a disease that requires aggressive treatment. Many researchers have direct financial relationships with the companies whose products they are evaluating. More militant "fat acceptors" reject any attempt to present obesity as a problem: Conventional wisdom, assuming obesity to be a health problem, is to be considered a prejudice, directly equivalent to the medicalization of homosexuality in the 19th century, and the consequent persecution of this minority.
Health effects of obesity
Opposing Campos are voices such as Greg Critser, who writes in Fat Land that the statistics such campaigners use are based on a selective sample of research data — a selection designed to emphasise obesity co-factors such as poor fitness, rather than obesity itself. Critser notes that advocates of the Obesity Myth position typically rely heavily on a study by Dr. Steven Blair at the Cooper Institute, Texas, which showed that fit, fat subjects were healthier than unfit, skinny subjects: :... Taking out the fitness variable and looking at body weight only, Blair admitted: "Men with a BMI of >30 were generally less physically fit and had more unfavorable risk factors than men in the lower BMI groups". Lower weight men had higher good cholesterol, lower bad cholesterol, and higher treadmill times than fatter men. "The highest death rate," he added, "was observed among those men in the highest BMI category and correspondingly lower death rates were observed in each subsequently lower BMI category." And when one looks at the difference between low fit men in all categories — which one might think would be most useful since most obese people are not fit — Blair's upbeat message fades: Normal weight nonfit men had an age-adjusted death rate (the number of excess deaths in the studied group) of 52.1; unfit fat men had the higher rate of 62.1. More: Unfit lean men were half as likely to have a history of hypertension than unfit fat men. In the real world, even according to Blairism, the fat are more likely to die early — and to live precariously — than the lean.
Medical responses to obesity
Conventional wisdom recommends that the obese adopt strategies to lose weight in order to mitigate the health risks associated with obesity. There is controversy both over what those strategies realistically include, and also whether such a goal does actually result in better health outcomes. Weight reduction strategies include dietary changes, exercise regimes, weight loss drugs, and surgical interventions (see Therapy, above, for complete list). Of these, "miracle diets" are most contested, with several studies suggesting that short-term weight loss typically results in metabolic adjustments leading to weight gain in the longer term. Conventional wisdom holds that obesity is caused by over-indulgence in fatty or sugary foods, portrayed as either a failure of will power or a species of addiction. Various specialists strongly oppose this view. For example, Professor Thomas Sanders of King's College London emphasises the need for balance between activity and consumption: :In trials, there is no evidence suggesting that reducing fat intake has an effect on obesity. As long as your expenditure equals what you eat, you won't put on weight, regardless of how high the fat content is in your diet (The Times, London, 10 March 2004).
Prevalence and public interest
What qualifies a medical condition as a matter of public interest, rather than a private health issue between doctor and patient, are its social costs. The estimation or measurement of the social cost of obesity is an extraordinarily hazardous statistical task, for two separate reasons. Firstly, the collation of evidence concerning the prevalence of obesity, or especially changing rates of prevalence, is open to several types of distortion. In the case of the UK, for one example, uninterpreted public health statistics may contradict the common belief that obesity is reaching epidemic proportions [http://www.spiked-online.com/Articles/0000000CA8D9.htm]. More generally, average weight increases with age — so a population with an increasing proportion of older people will have a higher average weight, regardless of changes to diet or activity. The Times Secondly, since obesity is the correlate of a long list of factors which have significant health consequences in their own right, there may be no fact of the matter about which costs to attribute to obesity per se, and which are more properly costed to these co-factors. For one example, the proven relationship between obesity and low social status means that any group of obese persons' health outcomes will be significantly lowered by their average access to medical care, as a socioeconomic class, which will be, on average, lower than that of any non-obese control group. Researchers from the U.S. Centers of Disease Control and Prevention in Atlanta reported that approximately 400,000 US deaths annually were associated with poor diet and little exercise, and that if the trend continued, this would be 500,000 in 2005, overtaking smoking as the leading cause of death. These statistics are fiercely contested [http://server1.consumerfreedom.com/article_detail.cfm/article/141], and error was admitted by the CDC in November 2004 [http://www.cbsnews.com/stories/2004/11/24/health/main657636.shtml]. In particular, studies of this nature are normally unable to distinguish causes of death, so include many accidental deaths, murders etc., which ought not to be costed to obesity. Canada and Europe are generally considered to be somewhat behind the United States in the trend towards overweight, with the rest of the world mixed. Some nations like Egypt, China and Mexico have also suffered from greatly increasing rates of obesity. In March 2005 the International Obesity Task Force, a global coalition of obesity scientists and research centres advising the European Union, estimated that Finland, Germany, Greece, Cyprus, the Czech Republic, Slovakia, and Malta have exceeded the United States figure of 67% for overweight or obese males. The task force estimated in 2003 that about 200m of the 350m adults living in what is now the European Union may be overweight or obese [http://www.guardian.co.uk/medicine/story/0,11381,1438700,00.html].
Policy responses to obesity
On top of controversies about the causes of obesity, and about its precise health implications, come policy controversies about the correct policy approach to obesity. The main debate is between "personal responsibility" advocates, who resist regulatory attempts to intervene in citizen's private dietary habits, and "public interest" advocates, who promote regulations, on the same public health grounds as the restrictions applied to tobacco products. In the U.S., a recent bout in this controversy involves the so-called Cheeseburger Bill, an attempt to indemnify food industry businesses from frivolous law suits by obese clients. "Personal responsibility" advocates work on the basis that, as the microbiologist Rene Dubos once said, health ought not to be considered an end in itself, but "the condition best suited to reach goals that each individual formulates for himself" [http://www.spiked-online.com/Articles/0000000CA7A4.htm]. Any other definition permits authorities to curtail the autonomy of the self-determining individual, imposing quantity over quality of life onto them, undermining their civil liberties. As much as principled doctors, personal responsibility arguments have also been offered by food producer lobbies. In 1961, for example, as President John F Kennedy raised concerns about a lack of fitness in American society, a spokesman for the U.S. Dairy industry, Frank R. Neu, wrote advertorials warning We May Be Sitting Ourselves To Death [http://www.theatlantic.com/issues/61nov/neu.htm]. Not food regulation, but personal exercising, is moved as the solution. The "public interest" advocate John Banzhaf has found a way to harness personal responsibility arguments to the public interest side of the debate in the U.S., via recent changes [http://banzhaf.net/docs/fatrates] to HMO regulations which enable health insurance providers to differentiate between obese and regular customers in their pricing. The "public interest" objective is that obese people will have to pay extra for their health maintenance, bringing "personal responsibility" to bear on their consumption choices. This new tactic is controversial itself — if a causal link pertains from low social status to obesity (see above), the net effect will be increased costs for low income members of HMOs, particularly ethnic minorities, and reduced costs for slim, middle class white members. On July 16, 2004, the United States Department of Health and Human Services officially classified obesity as a disease. Speaking to a Senate committee, Tommy Thompson, the Secretary of Health and Human Services, stated that Medicare would cover obesity-related health problems. However, reimbursement would not be given if a treatment was not proven to be effective.
See also

- Fat acceptance movement
- Fat admirer
- Feederism
- Chubby culture
- MOMO syndrome
- Pickwickian syndrome
- Healthy eating
- Dieting
- Super Size Me
References

- Janssen I, Katzmarzyk PT, Ross R. Waist circumference and not body mass index explains obesity-related health risk. Am J Clin Nutr 2004;79:379-84 PMID 14985210
- The Oxford English Dictionary (website)
- Powdermaker H. "An anthropological approach to the problem of obesity." Food and Culture: A Reader. Ed. Carole Counihan and Penny van Esterik. New York: Routledge, 1997. 206.
- Powdermaker, op. cit., 207.
- Powdermaker, ibid.
- Flier JS. Obesity wars: molecular progress confronts an expanding epidemic. Cell 2004;116:337-50. PMID 14744442.
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- Snow V, Barry P, Fitterman N, Qaseem A, Weiss K; Clinical Efficacy Assessment Subcommittee of the American College of Physicians. Pharmacologic and surgical management of obesity in primary care: a clinical practice guideline from the American College of Physicians. Ann Intern Med 2005;142:525-31. [http://www.annals.org/cgi/content/full/142/7/525 Fulltext]. PMID 15809464.
- Campos, Paul. The Obesity Myth. Gotham Books, May 2004. ISBN 1592400663.
- Critser, Greg. Fat Land: how Americans became the fattest people in the World. Houghton Miffin Jan 2003. ISBN 0618164723.
- Mokdad AH, Marks JS, Stroup DF, Gerberding JL. Actual causes of death in the United States, 2000. JAMA 2004;291:1238-45. PMID 15010446
External links

- [http://www.iotf.org/ International Task Force on Obesity]
- [http://www.asso.org.au Australasian Society for the Study of Obesity]
- [http://www.who.int/topics/obesity/en/ World Health Organization] - Obesity Pages
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Irritable bowel syndrome

In medicine (gastroenterology), irritable bowel syndrome (IBS) or spastic colon is a group of functional bowel disorders which are fairly common and make up 20–50% of visits to gastroenterologists. There are three forms, dependent on which symptom predominates: diarrhea-predominant (IBS-D), constipation-predominant (IBS-C) and IBS with alternating stool pattern (IBS-A). An important new IBS subtype, post-infectious IBS (IBS-PI), is drawing much clinical investigation.

Features

Symptoms of IBS are abdominal pain or discomfort associated with changes in bowel habits in the absence of any apparent structural abnormality. The pain is typically relieved by defecating. There appears to be an overlap of IBS with stress, chronic pelvic pain, fibromyalgia and various mental disorders (in a small minority). While no good explanation for this phenomenon exists, it does strengthen the view that there is a neurological and psychological component to IBS.

Diagnosis

Diagnostic criteria

In 1978 Manning et al., found, from questionaire data, that IBS sufferers reported four common symptoms. The Manning Criteria was established to distinguish organic causes for symptoms from those of IBS. In 1992 the Rome I Criteria was established by a multinational committee of specialists, which further refined the Manning Criteria. In 1998 the Rome Working Team proposed changes to the definition and diagnostic criteria for IBS to refelect new research data, and to improve clarity. The diagnosis of Irritable Bowel Syndrome has relied on a diagnosis of exclusion. Because the symptoms of IBS share the symptoms of so many other intestinal illnesses, it sometimes takes years before a correct diagnosis is made to exclude the obvious, and not so obvious, conditions which present symptoms similiar to IBS. Physicians rely on a variety of procedures and laboratory tests to confirm a diagnosis. The Rome II Criteria, however now defines markers which allows professionals to diagnose IBS after a careful examination of a sufferers medical history and physical abdominal examination which looks for any 'red flag' symptoms. Red Flag symptoms which are NOT typical of IBS:
- Pain that awakens/interfers with sleep
- Diarrhea that awakens/interfers with sleep
- Blood in your stool (visible or occult)
- Weight loss
- Fever
- Abnormal physical examination According to the Rome II consensus conference of the American Gastroenterological Association and international medical societies on functional bowel disorders, the diagnosis of IBS can be made when the following criteria are fulfilled: At least 12 weeks, which need not be consecutive, in the preceding 12 months of abdominal discomfort or pain that has 2 of 3 features: #Relieved with defecation; and/or #Onset associated with a change in frequency of stool; and/or #Onset associated with a change in form (appearance) of stool. Symptoms that cumulatively support the diagnosis of IBS
- Abnormal stool frequency (for research purposes, “abnormal” may be defined as greater than 3 bowel movements per day and less than 3 bowel movements per week);
- Abnormal stool form (lumpy/hard or loose/watery stool);
- Abnormal stool passage (straining, urgency, or feeling of incomplete evacuation);
- Passage of mucus;
- Bloating or feeling of abdominal distention. Supportive Symptoms of IBS: # Fewer than three bowel movements a week # More than three bowel movements a day # Hard or lumpy stools # Loose (mushy) or watery stools # Straining during a bowel movement # Urgency (having to rush to have a bowel movement) # Feeling of incomplete bowel movement # Passing mucus (white material) during a bowel movement # Abdominal fullness, bloating, or swelling Diarrhea-predominant: 1 or more of 2, 4, 6 and none of 1, 3, or 5; or: 2 or more of 2, 4, or 6 and one of 1 or 5. (3. Hard or lumpy stools do not qualify.) Constipation-predominant: 1 or more of 1, 3, 5 and none of 2, 4, or 6;or: 2 or more of 1, 3, or 5 and one of 2, 4 or 6.

Differential diagnosis

The diagnosis of a functional bowel disorder always presumes the absence of a structural or biochemical explanation for the symptoms. This can be excluded via:
- sigmoidoscopy or colonoscopy
- esophagogastroduodenoscopy (EGD, gastroscopy)
- abdominal ultrasound or CT scan
- blood tests: full blood count, liver enzymes, electrolytes, renal function
- stool chemistry (e.g. tests for exocrine pancreas insufficiency and other malabsorption conditions), stool microbiology, fecal fat
- H₂-tests for lactose intolerance and fructose malabsorption
- blood tests or deep duodenal biopsy for celiac disease While these modalities may be employed to rule out other causes of abdominal symptoms, they are not necessary to make a diagnosis of IBS. Depending on local practice, many doctors avoid overdiagnosing if the history is clearly suggestive of a functional bowel disorder.

Diagnostic tests

A diagnostic test for IBS via assessment of colonic/rectal hypersensitivity using a barostat is currently being discussed. However, sensitivity and specificity are not yet high enough to render the method widely applicable.

Pathophysiology

IBS is highly prevalent in the Western world, but despite the advancement of many theories, no clear cause has yet been established. Hypersensitivity of the gut is a major finding in most IBS patients. The association of IBS with stress is less clear, but studies have shown that there may be a correlation between IBS and prior sexual or physical abuse. Changes in colonic motility and immunologic causes have been discussed, as well as dietary causes. About 25% of patients develop symptoms after an episode of enteritis (partially after use of antibiotics). In these cases, a prolonged immune reaction is currently discussed as pathogenetic. So far, this is mainly based on experiments in the animal model. IBS is widely regarded as a conglomeration of disorders with similar symptoms but a different etiology (root cause). As with many other medical conditions, there is a lot of speculation about causes, including in the field of alternative medicine.

Treatment

One of the most important therapeutic measures is reassuring the patient that he has no fatal or otherwise threatening disease, as this is the major concern of patients seeking medical help. Dietary advice may be given and medication is an option in most forms.

Diet

There is no evidence that digestion of food is different in those with IBS compared to those without IBS. Although the exact cause of IBS is not known, there are factors that appear to aggravate symptoms or make a person feel worse. While dietary factors do not cause IBS, they may aggravate symptoms in some persons (IFFGD, 2004). Many people including physicians have noted a connection to diet. Definitive determination

Dietary fiber

Uses

Harmful effects

Sources of fiber

Fiber supplements

Psyllium husk

Methylcellulose

Polycarbophil

Vegetable gums

Further reading

References

External links

Gel

Applications

See also

Bile salts

Physiology

Four humours

See also

Cholesterol

History of the name

Physiology

Synthesis and intake

Properties

Regulation

Function

Excretion

Role in atheromatous disease

Cholesteric liquid crystals

See also

Sources

External links

Glucose

Structure

Isomers

Production

Natural

Commercial

Function

As an energy source

As a precursor

Sources and absorbtion

See also

External links

Lumen

Colon distention

Stool

Moisture

See also

Abrasion

Geographical

See also

Diverticulitis

Incidence

Causes

Presentation

Diagnosis

Treatment

Complications

Obesity

Definition

Etymology

Cultural and social significance

Culture and obesity

Popular culture

Causes

Causative factors

Evolutionary aspects

Neurobiological mechanisms

Societal causes

Poverty link

Complications

Therapy

Controversies

Medicalization of obesity

Health effects of obesity

Medical responses to obesity

Prevalence and public interest

Policy responses to obesity

See also