diabetestalk.net

Fructose Vs Glucose Metabolism

Fructose Metabolism: Relation To Food Intake & Metabolic Dysfunction

Fructose Metabolism: Relation To Food Intake & Metabolic Dysfunction

Diets containing large amounts of sucrose (a disaccharide of glucose and fructose) can utilize the fructose as a major source of energy. It should be pointed out that the difference between the amount of fructose available from sucrose obtained from cane or beet sugars is not significantly less than that from corn syrup. Corn syrup is somewhat improperly identified as high fructose corn syrup (HFCS) giving the impression that it contains a large amount of fructose. However, whereas the fructose content of sucrose is 50% (since it is a pure disaccharide of only glucose and fructose), the content in HFCS is only 55%. The reason HFCS has more than 50% fructose is because the glucose extracted from corn starch is enzymatically treated to convert some of the glucose to fructose. This is done in order to make the sugar sweeter which is why it is particularly popular in the food industry. Therefore, any disorder and/or dysfunction (see below), attributed to the consumption of fructose, can be manifest whether one consumes cane or beet sugar or HFCS. The pathway to utilization of fructose differs in muscle and liver due to the differential distribution of fructose phosphorylating enzymes. Hexokinases are a family of enzymes that phosphorylate hexose sugars such as glucose. Four mammalian isozymes of hexokinase are known (Types IIV), with the Type IV isozyme often referred to as glucokinase. Glucokinase is the form of the enzyme found in hepatocytes and pancreatic -cells. Several of the hexokinases (but not type IV) can phosphorylate various different hexoses including fructose. In addition to hexokinases, fructose can be phosphorylated by fructokinases. Fructokinases are formally referred to as ketohexokinases (KHK). There are two forms of KHK in mammals that result from alter Continue reading >>

Fructose In Perspective

Fructose In Perspective

Feinman and Fine; licensee BioMed Central Ltd.2013 Whether dietary fructose (as sucrose or high fructose corn syrup) has unique effects separate from its role as carbohydrate, or, in fact, whether it can be considered inherently harmful, even a toxin, has assumed prominence in nutrition. Much of the popular and scientific media have already decided against fructose and calls for regulation and taxation come from many quarters. There are conflicting data, however. Outcomes attributed to fructose obesity, high triglycerides and other features of metabolic syndrome are not found in every experimental test and may be more reliably caused by increased total carbohydrate. In this review, we try to put fructose in perspective by looking at the basic metabolic reactions. We conclude that fructose is best understood as part of carbohydrate metabolism. The pathways of fructose and glucose metabolism converge at the level of the triose-phosphates and, therefore, any downstream effects also occur with glucose. In addition, a substantial part of ingested fructose is turned to glucose. Regulation of fructose metabolism per se, is at the level of substrate control the lower Km of fructokinase compared to glucokinase will affect the population of triose-phosphates. Generally deleterious effects of administering fructose alone suggest that fructose metabolism is normally controlled in part by glucose. Because the mechanisms of fructose effects are largely those of a carbohydrate, one has to ask what the proper control should be for experiments that compare fructose to glucose. In fact, there is a large literature showing benefits in replacing total carbohydrate with other nutrients, usually fat, and such experiments sensibly constitute the proper control for comparisons of the two suga Continue reading >>

Evidence Shows Some Sugars Are Worse Than Others; Fructose Tops The List

Evidence Shows Some Sugars Are Worse Than Others; Fructose Tops The List

Evidence Shows Some Sugars Are Worse Than Others; Fructose Tops the List Written by Cameron Scott on January 29, 2015 Are all sugars created equal, or are some more likely to cause obesity and related diseases, including type 2 diabetes? A study published in the American Journal of Clinical Nutrition in 2004 proposed that the growing use of high-fructose corn syrup as a sweetener in processed foods could be linked to ballooning rates of obesity. It launched a long, contentious scientific debate. A recently published paper in the Mayo Clinic Proceedings wont settle the issue, but it does pose a significant new challenge to those who believe that a sugar is a sugar is a sugar. The comprehensive literature review claims to show for the first time that, calorie for calorie, added sugars especially fructose are more damaging to the bodys metabolic systems than other carbohydrates and are more likely to lead to type 2 diabetes and obesity. Forty percent of all American adults have some sort of insulin resistance, said James DiNicolantonio, PharmD, an associate editor at BMJ Open Heart, who co-authored the paper with Dr. Sean Lucan of the Albert Einstein College of Medicine. The paper argues that the most current guidelines for how much added sugar is safe to eat are grossly exaggerated. It suggests that just 5 to 10 percent of our total caloric intake should come from added sugar. That comes out to about 22 grams of sugar about half as much as a single can of soda. Related News: Soda Linked to Type 2 Diabetes Epidemic Why fructose, and why added sugar? All carbohydrates contain glucose. Some foods, notably fruits, also contain fructose. Fructose is sweeter than glucose, so its most often used as an added sugar in processed foods, whether in the form of high-fructose corn syr Continue reading >>

Glucose & Fructose Metabolism

Glucose & Fructose Metabolism

Glucose and fructose are simple sugars that have the same chemical formula with a different structural arrangement of the atoms. Glucose is a source of energy for all of your tissues, and can be stored by the body for energy upon demand. It's also used to make other sugars needed in your genetic material and connective tissues. Fructose is primarily metabolized in your liver, and excesses are used to make body fat. Glycolysis is the initial process in the harvesting of energy from glucose. After glucose enters your tissue cells, an enzyme called phosphofructokinase determines whether or not glucose will be used for energy. If your cell needs energy, phosphofructokinase will allow glycolysis to proceed. If your cell is well-supplied with oxygen, glucose will be completely burned for energy, which is called aerobic glycolysis. If oxygen is in short supply, glucose will only be partially burned and then converted into lactic acid. This is called anaerobic glycolysis and it occurs when your muscles are working hard but not getting enough oxygen. Glycogen If glucose enters your cells and is not immediately needed for energy, glucose molecules can be linked together in branching chains and stored as a form of starch called glycogen. When energy is needed, glycogen can be broken down into glucose. Your muscles store glycogen for their own use. However, your liver can store large amounts of glucose as glycogen, and if your blood glucose level gets too low, glycogen can be broken down into glucose and released into your blood for use by other tissues. Gluconeogenesis When your blood glucose level falls too low, your liver can also make glucose from non-glucose sources and then secrete the glucose into your blood for other tissues to use for energy. This process is called glucone Continue reading >>

Challenging The Fructose Hypothesis: New Perspectives On Fructose Consumption And Metabolism

Challenging The Fructose Hypothesis: New Perspectives On Fructose Consumption And Metabolism

Challenging the Fructose Hypothesis: New Perspectives on Fructose Consumption and Metabolism To whom correspondence should be addressed. E-mail: [email protected] . Search for other works by this author on: Advances in Nutrition, Volume 4, Issue 2, 1 March 2013, Pages 246256, John S. White; Challenging the Fructose Hypothesis: New Perspectives on Fructose Consumption and Metabolism, Advances in Nutrition, Volume 4, Issue 2, 1 March 2013, Pages 246256, The field of sugar metabolism, and fructose metabolism in particular, has experienced a resurgence of interest in the past decade. The fructose hypothesis alleges that the fructose component common to all major caloric sweeteners (sucrose, high-fructose corn syrup, honey, and fruit juice concentrates) plays a unique and causative role in the increasing rates of cardiovascular disease, hypertension, diabetes, cancer, and nonalcoholic fatty liver disease. This review challenges the fructose hypothesis by comparing normal U.S. levels and patterns of fructose intake with contemporary experimental models and looking for substantive cause-and-effect evidence from real-world diets. It is concluded that 1) fructose intake at normal population levels and patterns does not cause biochemical outcomes substantially different from other dietary sugars and 2) extreme experimental models that feature hyperdosing or significantly alter the usual dietary glucose-to-fructose ratio are not predictive of typical human outcomes or useful to public health policymakers. It is recommended that granting agencies and journal editors require more physiologically relevant experimental designs and clinically important outcomes for fructose research. Few nutrients have received the level of scrutiny in the past 30 y that fructose has. It has be Continue reading >>

Fructose - An Overview | Sciencedirect Topics

Fructose - An Overview | Sciencedirect Topics

Fructose is a 6-carbon ketose found in fruit and honey as a monosaccharide, and in sucrose (a disaccharide of fructose and glucose). J.M. Johnson, F.D. Conforti, in Encyclopedia of Food Sciences and Nutrition (Second Edition) , 2003 Fructose is a monosaccharide. Fructose bonded with glucose, another monosaccharide, forms sucrose, or table sugar. Fructose also occurs naturally in abundance in fruits (Table 1) and in lesser amounts in tuberous vegetables such as onions and potatoes. These sources alone contribute some 4060% of an individual's total fructose intake. However, the major source of fructose as an ingredient in food is from the hydrolyzation of starch to glucose, which is then converted to fructose. (See CARBOHYDRATES | Classification and Properties.) Fruits are a rich source of mono- and disaccharides. Dates contain up to 48.5% sucrose, and dried figs contain a mixture of 30.9% fructose and 42.0% glucose. The sucrose content of most fruit and fruit juices is low, though some varieties of melons, peaches, pineapple, and tangerine contain 69% sucrose, and mango contains 11.6% sucrose. Reducing sugars (primarily a mixture of fructose and glucose) are the main soluble carbohydrate of most fruits and account for 70% of seedless raisins. Vegetables contain substantially less fructose and glucose than fruits, and the only significant source of sucrose is sugar beets. In the late 19th century corn or potato starch was hydrolyzed with dilute acid to yield glucose and dextrins for commercial purposes. In the 1940s, cornstarch was the primary choice for the production of glucose and the introduction of enzyme technology for hydrolysis reactions contributed to the development of glucose syrups to fructose syrups of specified glucose content. The conversion of glucose syr Continue reading >>

Carbohydrate Metabolism

Carbohydrate Metabolism

The metabolism of the sugars found in our food is discussed in all textbooks and I will not take up all of the details here. The points I do wish to discuss are concerned with maintenance of blood sugar levels under differing physiological conditions. How do we start up storage of glucose after a meal? How do we preserve blood glucose levels between meals? What are the differences in metabolism of common sugars in various organs? Transport of Glucose in and out of the Liver The whole thing begins with transport of sugars over tissue membranes. These "small" sugars (glucose, fructose and galactose) are so large that they cannot cross cell membranes without "carriers". Sugar carriers are proteins embedded in the cell's outer membrane that provide transport systems for monosaccharides. The glucose transport protein family (called GLUT) is discussed elsewhere in MedBio. Click here for more information . The point to note now is that these carriers are bidirectional; they can transport glucose both into and out of cells. The direction of movement is determined by the concentrations of glucose in and outside of the liver cell. This is illustrated in the figure to the left. Drawing "1" shows the situation when the portal blood and the liver cell have equal concentrations of glucose; sugar moves in both directions simultaneously. This may seem to be wasteful, but gears the system to react to small changes in glucose concentration. The second drawing shows what happens when blood glucose tends to fall. Glucose production in the liver accelerates and the net flow of glucose is outward, stabilizing the blood sugar level. This is extremely important. The total amount of sugar present in the blood can support resting activity for about 40 minutes. Just walking increases glucose use Continue reading >>

Fructolysis - Wikipedia

Fructolysis - Wikipedia

This article has multiple issues. Please help improve it or discuss these issues on the talk page . This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed. This article possibly contains original research . Please improve it by verifying the claims made and adding inline citations . Statements consisting only of original research should be removed. ( Learn how and when to remove this template message ) Fructolysis refers to the metabolism of fructose from dietary sources. Though the metabolism of glucose through glycolysis uses many of the same enzymes and intermediate structures as those in fructolysis, the two sugars have very different metabolic fates in human metabolism. Unlike glucose, which is metabolized widely in the body, fructose is metabolized almost completely in the liver in humans, where it is directed toward replenishment of liver glycogen and triglyceride synthesis. [1] Under one percent of ingested fructose is directly converted to plasma triglyceride. [2] 29% - 54% of fructose is converted in liver to glucose, and about quarter of fructose is converted to lactate . 15% - 18% is converted to glycogen . [3] Glucose and lactate are then used normally as energy to fuel cells all over the body. [2] Fructose is a dietary monosaccharide present naturally in fruits and vegetables , either as free fructose or as part of the disaccharide sucrose , and as its polymer inulin . It is also present in the form of refined sugars including granulated sugars (white crystalline table sugar, brown sugar , confectioner's sugar , and turbinado sugar ), refined crystalline fructose and as high fructose corn syrups . About 10% of the calories contai Continue reading >>

Fructose Vs. Glucose

Fructose Vs. Glucose

While fructose and glucose have the same calorific value, the two sugars are metabolized differently in the body. Fructose has a lower glycemic index than glucose but has a much higher glycemic load. Fructose causes seven times as much cell damage as does glucose, because it binds to cellular proteins seven times faster; and it releases 100 times the number of oxygen radicals (such as hydrogen peroxide, which kills everything in sight).[1] Fructose is a simple sugar commonly found in fruits and vegetables. Vast quantities are also manufactured in the lab. Glucose, also known as grape or blood sugar, is present in all major carbohydrates like starch and table sugar. While both are a good source of energy, excess of glucose can be fatal to diabetic patients, and excess of fructose can lead to health problems like insulin resistance and liver disease. Comparison chart Source of energy. Often added to food and drinks to improve taste. Source of energy. Fuels cellular respiration. Photosynthesis, the breakdown of glycogen. Vast quantities produced artificially in the lab by the food industry. Photosynthesis, the breakdown of glycogen. Honey, flowers, berries, most root vegetables. All major carbohydrates Continue reading >>

The Difference In How Fructose And Glucose Affect Your Body

The Difference In How Fructose And Glucose Affect Your Body

My regular readers know that I consider agave to be a BIG enemy to health and beauty- which is very high in fructose (up to 97% fructose). It truly irks me that sly marketing makes the general public think agave is a “healthy” sweetener, and that it continues to be used in “health” products purported to be better than regular baked or other goods, as well as in many restaurants. It is not. There is a myth that exists that fructose is a “healthy” sugar while glucose is bad stuff. In fact, in recent years, there has been a rise in sweeteners that contain this “healthy” sugar, such as the dreaded agave nectar. I sincerely hope that this information (please help spread it!) makes more people aware of the differences in sugar types, and makes more people know to avoid agave at all costs. S.O.S: Save Our Skin!!! Fructose Fructose is one type of sugar molecule. It occurs naturally in fresh fruits, giving them their sweetness. Because of this, many people consider fructose “natural,” and assume that all fructose products are healthier than other types of sugar. Likewise, fructose has a low glycemic index, meaning it has minimal impact on blood glucose levels. This has made it a popular sweetener with people on low-carbohydrate and low-glycemic diets, which aim to minimize blood glucose levels in order to minimize insulin release. But the glycemic index is not the sole determining factor in whether a sweetener is “healthy” or desirable to use. Because fructose is very sweet, fruit contains relatively small amounts, providing your body with just a little bit of the sugar, which is very easily handled. If people continued to eat fructose only in fruit and occasionally honey as our ancestors did, the body would easily process it without any problems. Unfortu Continue reading >>

Difference Between Glucose And Fructose

Difference Between Glucose And Fructose

Similarities of glucose and fructose Before going through the differences, it is important to note that there are some common characteristics of glucose and fructose, exerting varied effects on the body, and undergoing different metabolic processes. Both fructose and glucose are monosaccharides, have the same caloric values (roughly 4Cal/g), and the same molecular formula of CC6H1206. Differences between glucose and fructose Fructose: is poorly absorbed and can cause fructose intolerance. It is moved to the colon, where it undergoes fermentation by bacteria producing gas, bloating and diarrhea. Glucose: is well absorbed. Brain interaction (4) Fructose: is slowly up taken through the brain barrier, causing the reduction of neural activity. Glucose: is up taken quickly to the brain barrier where it is metabolised using most of the oxygen available in the brain. Glucose raises the level of neural activity for about 20 minutes after its consumption. Fructose: is mainly (but not exclusively) metabolised by the liver. Other cells that accept fructose (although to a much lesser extent) are testicles, kidneys, skeletal muscles, fat tissue and brain. Fructose is up taken to the cells via a transporter called GLUT5 and also via GLUT2, to a smaller extent, which accepts fructose to the liver cells. Glucose: is up taken to most of the cells in the body for metabolism. It uses the following transporters to distribute glucose to corresponding cells: GLUT1 (to all cells), GLUT2 (to gut, liver and pancreas), GLUT3 (to central nervous system and brain), GLUT4 (to cells that need insulin to be up-taken such as skeletal muscles, fatty tissue and heart). Diabetics risk (7) Fructose: presents a long term risk for diabetics. Fructose only slightly increases blood glucose levels and insulin p Continue reading >>

Fructose Vs. Glucose And Metabolism: Do The Metabolic Differences Matter?

Fructose Vs. Glucose And Metabolism: Do The Metabolic Differences Matter?

1. Curr Opin Lipidol. 2014 Feb;25(1):8-19. doi: 10.1097/MOL.0000000000000042. Fructose vs. glucose and metabolism: do the metabolic differences matter? Sievenpiper JL(1), de Souza RJ, Cozma AI, Chiavaroli L, Ha V, Mirrahimi A. (1)aToronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto bDepartment of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University cDepartment of Clinical Epidemiology and Biostatistics, Faculty of Health Sciences, McMaster University, Hamilton dDepartment of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto eSchool of Medicine, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada. PURPOSE OF REVIEW: Fructose is seen as uniquely contributing to the pandemics of obesity and its cardiometabolic complications. Much of the evidence for this viewderives from the unique biochemical, metabolic, and endocrine responses thatdifferentiate fructose from glucose. To understand whether these proposedmechanisms result in clinically meaningful modification of cardiovascular risk inhumans, we update a series of systematic reviews and meta-analyses of controlled feeding trials to assess the cardiometabolic effects of fructose in isocaloricreplacement for glucose.RECENT FINDINGS: A total of 20 controlled feeding trials (n = 344) haveinvestigated the effect of fructose in/on cardiometabolic endpoints. Pooledanalyses show that although fructose may increase total cholesterol, uric acid,and postprandial triglycerides in isocaloric replacement for glucose, it does notappear to be any worse than glucose in its effects on other aspects of the lipid profile, insulin, or markers of nonalcoholic fatty liver disease. Continue reading >>

Fructose Vs. Glucose And Metabolism: Do The Metabolic Differences Matter?

Fructose Vs. Glucose And Metabolism: Do The Metabolic Differences Matter?

Fructose is seen as uniquely contributing to the pandemics of obesity and its cardiometabolic complications. Much of the evidence for this view derives from the unique biochemical, metabolic, and endocrine responses that differentiate fructose from glucose. To understand whether these proposed mechanisms result in clinically meaningful modification of cardiovascular risk in humans, we update a series of systematic reviews and meta-analyses of controlled feeding trials to assess the cardiometabolic effects of fructose in isocaloric replacement for glucose.A total of 20 controlled feeding trials (n = 344) have investigated the effect of fructose in/on cardiometabolic endpoints. Pooled analyses show that although fructose may increase total cholesterol, uric acid, and postprandial triglycerides in isocaloric replacement for glucose, it does not appear to be any worse than glucose in its effects on other aspects of the lipid profile, insulin, or markers of nonalcoholic fatty liver disease. It may also have important advantages over glucose for body weight, glycemic control, and blood pressure.Depending on the cardiometabolic endpoint in question, fructose has variable effects when replacing glucose. In the absence of clear evidence of net harm, there is no justification to replace fructose with glucose in the diet. Do you want to read the rest of this article? ... The relationship between SSB and cardiometabolic diseases seen in epidemiological studies reflects potential combined effects of fructose and glucose or unique effects of fructose alone. The current data suggest a causative relationship between the intake of sweeteners, particularly fructose, and the increased prevalence of nonalcoholic fatty liver disease and dyslipidemia [1,3,4], especially postprandial plasma Continue reading >>

Fructose Vs. Glucose And Metabolism: Do The Metabolic Differences Matter?

Fructose Vs. Glucose And Metabolism: Do The Metabolic Differences Matter?

Purpose of reviewFructose is seen as uniquely contributing to the pandemics of obesity and its cardiometabolic complications. Much of the evidence for this view derives from the unique biochemical, metabolic, and endocrine responses that differentiate fructose from glucose. To understand whether these proposed mechanisms result in clinically meaningful modification of cardiovascular risk in humans, we update a series of systematic reviews and meta-analyses of controlled feeding trials to assess the cardiometabolic effects of fructose in isocaloric replacement for glucose. Recent findingsA total of 20 controlled feeding trials (n = 344) have investigated the effect of fructose in/on cardiometabolic endpoints. Pooled analyses show that although fructose may increase total cholesterol, uric acid, and postprandial triglycerides in isocaloric replacement for glucose, it does not appear to be any worse than glucose in its effects on other aspects of the lipid profile, insulin, or markers of nonalcoholic fatty liver disease. It may also have important advantages over glucose for body weight, glycemic control, and blood pressure. SummaryDepending on the cardiometabolic endpoint in question, fructose has variable effects when replacing glucose. In the absence of clear evidence of net harm, there is no justification to replace fructose with glucose in the diet. Supplemental Digital Content is available in the text aToronto 3D Knowledge Synthesis and Clinical Trials Unit, Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto bDepartment of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University cDepartment of Clinical Epidemiology and Biostatistics, Faculty of Health Sciences, McMaster University, Hamilton dDepartment of Continue reading >>

Fructose Affects Your Brain Very Differently Than Glucose

Fructose Affects Your Brain Very Differently Than Glucose

Cardiovascular disease , arthritis, gout , and cancer Adding insult to injury, HFCS ismost oftenmade from genetically modified (GM) corn, which is fraught with its own well documented side effects and health concerns , from an increased risk of developing food allergies to the risk of increased infertility in future generations. Beware: Mixing Fructose with Glucose Increases Destructive Effect Fructose consumption clearly causes insulin resistance whereas straight glucose does not. However, it's worth knowing that glucose accelerates fructose absorption! So when you mix glucose and fructose together, you absorb more fructose than if you consumed fructose alone... This is an important piece of information if you are struggling to control your weight. Remember, sucrose, or table sugar, is exactly this blend -- fructose plus glucose. So, the key to remember is to not get too nit-picky about the names of the sugars. ALL of these contribute to decreased health: Crystalline fructose , and any other high-fructose sweetener they may dream up Natural fructose in the form of fruits, fruit juices, and natural sweeteners such as honey and agave. Is Fructose from HFCS Worse than Fructose from Table Sugar? High fructose corn syrup is about 55 percent fructose while table sugar is about 50 percent. The fructose in the corn syrup is also dissociated from the glucose, unlike table sugar which has it attached. So HFCS is clearly worse than table sugar, but not orders of magnitude. It is only marginally worse. The MAIN reason why fructose and HFCS are so bad is that in the mid 70s two things happened. Earl Butz changed the US Agriculture policy to massively subsidize corn production in the US, and scientists also figured out how to make HFCS in the lab from corn. The combination of these Continue reading >>

More in blood sugar