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 >>
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Is Fructose Bad For You?
One of many controversies mixing up the field of nutrition is whether the use of high-fructose corn syrup in soft drinks and other foods is causing the paired epidemics of obesity and diabetes that are sweeping the United States and the world. I’ve ignored this debate because it never made sense to me—high-fructose corn syrup is virtually identical to the refined sugar it replaces. A presentation I heard yesterday warns that the real villain may be fructose—a form of sugar found in fruits, vegetables, and honey. It may not matter whether it’s in high-fructose corn syrup, refined sugar, or any other sweetener. Sounding the alarm is Dr. Robert H. Lustig, a professor of pediatrics and an obesity specialist at the University of California, San Francisco. He is a key figure in a recent New York Times article called “Is Sugar Toxic?” Here’s some background and the gist of the presentation Lustig gave as part of a weekly seminar sponsored by Harvard School of Public Health’s Department of Nutrition. (You can watch Lustig’s entire talk or a view a similar version on YouTube.) When fructose is joined to glucose, it makes sucrose. Sucrose is abundant in sugar cane, sugar beets, corn, and other plants. When extracted and refined, sucrose makes table sugar. In the 1800s and early 1900s, the average American took in about 15 grams of fructose (about half an ounce), mostly from eating fruits and vegetables. Today we average 55 grams per day (73 grams for adolescents). The increase in fructose intake is worrisome, says Lustig, because it suspiciously parallels increases in obesity, diabetes, and a new condition called nonalcoholic fatty liver disease that now affects up to one-third of Americans. (You can read more about nonalcoholic fatty liver disease in a Harvard Continue reading >>
Are Glucose And Fructose Metabolized Differently?
Are glucose and fructose metabolized differently? cancer , diabetes , fructose , glucose , heart disease , insulin efficiency , insulin resistance , Olumia Life , sugar Glucose and fructose may both be sugars, but your body has a much easier and more productive time with glucose. When you eat the starchy or sweet foods that contain glucose (like pasta, fruits, bread, potatoes, rice, vegetables and much more), your body is able to send it directly down your bloodstream to provide energy to your cells. Fructose is not so fast. Rather than being sent through the body straight away to be used as energy, it has to first be metabolized by the liver. Thats not necessarily a bad thing, though, as fructose occurs naturally in some foods, like fruits. However, when you eat too many sugary and sugar-added foods, including processed food, sodas, etc., more fructose needs to be metabolized than expected and the liver gets overloaded. When too much fructose is arriving at your liver, it is more likely to be stored as fat than used as energy. Obviously, this results in weight gain, but it can also lead to lower insulin efficiency and higher insulin resistance, which in turn can cause a host of negative effects on your health, even leading to heart disease, cancer, diabetes and stroke. Continue reading >>
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 >>
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 >>
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 >>
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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 >>
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Sucrose, High-fructose Corn Syrup, And Fructose, Their Metabolism And Potential Health Effects: What Do We Really Know?
Sucrose, High-Fructose Corn Syrup, and Fructose, Their Metabolism and Potential Health Effects: What Do We Really Know? University of Central Florida Medical School, Orlando,FL and Rippe Lifestyle Institute, Shrewsbury, MA To whom correspondence should be addressed. E-mail: [email protected] . Search for other works by this author on: Laboratory of Applied Physiology, Department of Health Professions, University of Central Florida, Orlando, FL Search for other works by this author on: Advances in Nutrition, Volume 4, Issue 2, 1 March 2013, Pages 236245, James M. Rippe, Theodore J. Angelopoulos; Sucrose, High-Fructose Corn Syrup, and Fructose, Their Metabolism and Potential Health Effects: What Do We Really Know?, Advances in Nutrition, Volume 4, Issue 2, 1 March 2013, Pages 236245, Both controversy and confusion exist concerning fructose, sucrose, and high-fructose corn syrup (HFCS) with respect to their metabolism and health effects. These concerns have often been fueled by speculation based on limited data or animal studies. In retrospect, recent controversies arose when a scientific commentary was published suggesting a possible unique link between HFCS consumption and obesity. Since then, a broad scientific consensus has emerged that there are no metabolic or endocrine response differences between HFCS and sucrose related to obesity or any other adverse health outcome. This equivalence is not surprising given that both of these sugars contain approximately equal amounts of fructose and glucose, contain the same number of calories, possess the same level of sweetness, and are absorbed identically through the gastrointestinal tract. Research comparing pure fructose with pure glucose, although interesting from a scientific point of view, has limited applicatio Continue reading >>
Spotlight On Sugar
We encounter sugar in two different ways in our food: sugars that exist in unprocessed foods such as fruits, vegetables, and dairy products, and sugars that are added to packaged foods to boost flavor or allow food to be more shelf-stable. Added sugars are not chemically different from naturally occurring sugars. Both are broken down in the body using the same enzymatic processes. However, the amount and form in which we consume the sugars—in fruits and vegetables, in sodas, or in other processed foods—affects how quickly the body absorbs them, and how the body signals and experiences satiety, or feelings of fullness. Digestible carbohydrates, including “complex” starches and “simple” sugars, are all nutritionally similar in that they each provide 4 calories per gram. They are also chemically similar: more-complex carbohydrates have to be broken into simple sugars before they can be absorbed, transported by the bloodstream, and used for energy. Carbohydrate breakdown takes place high in the digestive tract, and with high efficiency. Starch is broken into glucose units and absorbed at about the same rate as pure glucose. Likewise, sucrose (a disaccharide made up of glucose paired with fructose) is clipped apart and absorbed about as quickly as high fructose corn syrup (a mixture of individual glucose and fructose units). Glucose and fructose have the same chemical formula: C6H12O6. But the atoms are arranged differently, giving the two sugars different chemical properties. The chemical structures of fructose and glucose influence their sweetness and how they are processed in the body. Sweetness Fructose tastes twice as sweet as glucose, and sucrose (composed of fructose and glucose linked together) is somewhere in between. The proportion of these sugars in fo Continue reading >>
All About Fructose
What is fructose? Fructose is a monosaccharide, the simplest form of carbohydrate. As the name implies, mono (one) saccharides (sugar) contain only one sugar group; thus, they can’t be broken down any further. Each subtype of carbohydrate has different effects in the body depending on the structure and source (i.e. what food it comes from). The chemical structure affects how quickly and/or easily the carbohydrate molecule is digested/absorbed. The source affects whether other nutrients are provided along with the carbohydrate. For example, both high fructose corn syrup (HFCS) and fruit contain fructose, but their effects in the body are different. HFCS is essentially a simple fructose delivery system – there’s nothing else to it, while fruit contains additional nutrients along with fibre, which affect digestion and absorption of the fructose. Plus, the amount of fructose in the average apple is much less than, say, the average can of soda. Fructose has a unique texture, sweetness, rate of digestion, and degree of absorption that is different from glucose, which is the sugar that most of our ingested dietary carbohydrates become when they hit the bloodstream. Fructose is absorbed through the intestine via different mechanisms than glucose Fructose has a slower rate of uptake Unlike glucose, fructose does not stimulate a substantial insulin release Fructose is transported into cells via a different transporter than glucose Once fructose is in the liver, it can provide glycerol, the backbone of fat, and increase fat formation Some people may be unable to completely absorb fructose when given in a high dose of around 50 grams (Note: that’s an extremely high amount of fructose. We’re talking 4-5 medium apples. Yet a 16 oz juice with HFCS can provide around 45 grams Continue reading >>
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.  Under one percent of ingested fructose is directly converted to plasma triglyceride.  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 .  Glucose and lactate are then used normally as energy to fuel cells all over the body.  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 >>
Sugar May Be Bad, But This Sweetener Called Fructose Is Far More Deadly
By Dr. Mercola A 2009 study from University of California, Davis takes its place in a growing lineup of scientific studies demonstrating that consuming high-fructose corn syrup is the fastest way to trash your health. It is now known without a doubt that sugar in your food, in all its myriad of forms, is taking a devastating toll. And fructose in any form -- including high-fructose corn syrup (HFCS) and crystalline fructose -- is the worst of the worst! Fructose, a cheap sweetener usually derived from corn, is used in thousands of food products and soft drinks. Excessive fructose consumption can cause metabolic damage and triggers the early stages of diabetes and heart disease, which is what the Davis study showed. Dr. Richard Johnson also does a fabulous job of comprehensively reviewing this important topic in his new book The Fat Switch. In the study, over the course of 10 weeks, 16 volunteers on a controlled diet including high levels of fructose produced new fat cells around their heart, liver, and other digestive organs. They also showed signs of food-processing abnormalities linked to diabetes and heart disease. Another group of volunteers on the same diet, but with glucose sugar replacing fructose, did not have these problems. Fructose is a major contributor to: Elevated triglycerides and elevated LDL Depletion of vitamins and minerals Cardiovascular disease, liver disease, cancer, arthritis, and even gout A Calorie Is Not a Calorie Glucose is the form of energy you were designed to run on. Every cell in your body, every bacterium -- and in fact, every living thing on Earth -- uses glucose for energy. If you received your fructose only from vegetables and fruits (where it originates) as most people did a century ago, you'd consume about 15 grams per day -- a far Continue reading >>
Fructose Metabolism In Humans What Isotopic Tracer Studies Tell Us
Fructose metabolism in humans what isotopic tracer studies tell us 1Compliance, Archer Daniels Midland Company, 1001 North Brush College Road, Decatur, IL, 62521, USA Received 2012 Aug 3; Accepted 2012 Sep 24. Copyright 2012 Sun and Empie; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article has been cited by other articles in PMC. Fructose consumption and its implications on public health are currently under study. This work reviewed the metabolic fate of dietary fructose based on isotope tracer studies in humans. The mean oxidation rate of dietary fructose was 45.0% 10.7 (mean SD) in non-exercising subjects within 36 hours and 45.8% 7.3 in exercising subjects within 23 hours. When fructose was ingested together with glucose, the mean oxidation rate of the mixed sugars increased to 66.0% 8.2 in exercising subjects. The mean conversion rate from fructose to glucose was 41% 10.5 (mean SD) in 36 hours after ingestion. The conversion amount from fructose to glycogen remains to be further clarified. A small percentage of ingested fructose (<1%) appears to be directly converted to plasma TG. However, hyperlipidemic effects of larger amounts of fructose consumption are observed in studies using infused labeled acetate to quantify longer term de novo lipogenesis. While the mechanisms for the hyperlipidemic effect remain controversial, energy source shifting and lipid sparing may play a role in the effect, in addition to de novo lipogenesis. Finally, approximately a quarter of ingested fructose can be converted into lactate within a few of hours. The reviewed Continue reading >>
How Bad Is Fructose?
From the Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA Reprints not available. Address correspondence to GA Bray, Boyd Professor, Pennington Biomedical Research Center, LSU System, 6400 Perkins Road, Baton Rouge, LA 70808. E-mail: [email protected] . Search for other works by this author on: The American Journal of Clinical Nutrition, Volume 86, Issue 4, 1 October 2007, Pages 895896, George A Bray; How bad is fructose?, The American Journal of Clinical Nutrition, Volume 86, Issue 4, 1 October 2007, Pages 895896, This issue of the Journal contains another disturbing article on the biology of fructose ( 1 ). Why is fructose of concern? First, it is sweeter than either glucose or sucrose. In fruit, it serves as a marker for foods that are nutritionally rich. However, in soft drinks and other sweets, fructose serves to reward sweet taste that provides calories, often without much else in the way of nutrition. Second, the intake of soft drinks containing high-fructose corn syrup (HFCS) or sucrose has risen in parallel with the epidemic of obesity, which suggests a relation ( 2 ). Third, the article in this issue of the Journal ( 1 ) and another article published elsewhere last year ( 3 ) implicate dietary fructose as a potential risk factor for cardiovascular disease. The intake of dietary fructose has increased significantly from 1970 to 2000. There has been a 25% increase in available added sugars during this period ( 4 ). The Continuing Survey of Food Intake by Individuals from 1994 to 1996 showed that the average person had a daily added sugars intake of 79 g (equivalent to 316 kcal/d or 15% of energy intake), approximately half of which was fructose. More important, persons who are ranked in the top one-third of fructose consum Continue reading >>
Sugarscience.ucsf.edu | Metabolizing Sugar
A broad term meaning any bodily process in which the liver is injured or does not work as it is supposed to. In this website we focus on liver diseases in which the diet hurts the liver Usually shortened to just diabetes. Sometimes called sugar diabetes. Look at Type 1 Diabetes and Type 2 Diabetes for more information A type of fat in our body and our food. Three fatty acids are combined with another chemical called glycerol to form a triglyceride. Sugars are chemicals made of carbon, hydrogen, and oxygen found which taste sweet and are found in food. They are an important part of what we eat and drink and of our bodies. On this site, sugar is used to mean simple sugars (monosaccharides) like fructose or glucose, and disaccharides like table sugar (sucrose). Sucrose is two simple sugars stuck together for example (see Table sugar). Sugars are a type of carbohydrate. Carbohydrates are energy sources for our bodies Sugars enter the blood stream very quickly after being eaten. One of the three major groups of nutrients we eat. Much of this website is related to problems associated with too much fat storage in the body. Each gram of fat produces 9 calories of energy if burned by the body as fuel. Fat can be stored in many places in the body. We generally think of fat as under the skin (subcutaneous), but the fat that may be most damaging to us is the fat stored in the liver and around the organs of the abdomen (intrahepatic and visceral or abdominal or intra-abdominal) A sugar that we eat. Also called fruit sugar. Most fructose comes in sucrose (table sugar, cane sugar, beet sugar), or from high-fructose corn syrup. Glucose is a sugar we eat. It is found in starch. It is the main fuel for our bodies. It is the sugar measured when we have a blood test to measure the blood s Continue reading >>