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U of I study: Fructose metabolism more complicated than was thought
December 10, 2008A new University of Illinois study suggests that we may pay a price for ingesting too much fructose. According to lead author Manabu Nakamura, dietary fructose affects a wide range of genes in the liver that had not previously been identified.
Chances are you consume quite a bit of fructose. Most Americans do-in refined sugars such as sucrose or table sugar (which is half fructose) and in high-fructose corn syrup, used in products as diverse as soft drinks, protein bars, and fruit juice.
But many scientists believe that high dietary fructose contributes to the development of metabolic syndrome, a group of risk factors that predict heart disease and Type 2 diabetes.
"For this reason, it's important for scientists to understand exactly how consuming high amounts of fructose affects human health," said Nakamura, a U of I associate professor of food science and human nutrition.
Nakamura's lab is continuing to study the metabolism of fructose with an eye to making recommendations about its dietary use.
His study shows that the metabolism of fructose is more complex than the data had indicated. "Our gene-expression analysis showed that both insulin-responsive and insulin-repressive genes are induced during this process. Our bodies can do this, but it's complicated, and we may pay a price for it," he said.
According to the scientist, most carbohydrates are handled fairly simply by our bodies. They are converted quickly to glucose and used for energy or stored as fat. "When we are eating, blood sugar--and insulin production--goes up. When we sleep or fast, it goes down," he said.
The process is not so simple with fructose, he noted. "In order for fructose to be metabolized, the body has to create both fasted and fed conditions. The liver is really busy when you eat a lot of fructose."
Because, unlike glucose, fructose metabolism occurs mainly in the liver, Nakamura wanted to gain a complete picture of gene expression in the liver during fructose metabolism.
In Nakamura's study, 24 rats were fed either a 63 percent glucose or fructose diet four hours a day for two weeks; at the end of this period, half the animals fasted for 24 hours before the scientists performed a gene expression analysis; the other half were examined at the end of a four-hour feeding.
Fructose feeding not only induced a broader range of genes than had previously been identified, there were simultaneous increases in glycogen (stored glucose) and triglycerides in the liver.
"To our surprise, a key regulatory enzyme involved in the breakdown of glucose was about two times higher in the fructose-fed group than in the glucose-fed group," Nakamura said.
The study also suggests that a protein called carbohydrate response element binding protein is responsible for the fructose effect on certain genes that trigger the production of fat, he said.
"We're continuing to assess the risk of fructose insulin resistance and the consequent risk for development of diabetes," he said.
University of Illinois at Urbana-Champaign
"For this reason, it's important for scientists to understand exactly how consuming high amounts of fructose affects human health," said Nakamura, a U of I associate professor of food science and human nutrition.
Nakamura's lab is continuing to study the metabolism of fructose with an eye to making recommendations about its dietary use.
His study shows that the metabolism of fructose is more complex than the data had indicated. "Our gene-expression analysis showed that both insulin-responsive and insulin-repressive genes are induced during this process. Our bodies can do this, but it's complicated, and we may pay a price for it," he said.
According to the scientist, most carbohydrates are handled fairly simply by our bodies. They are converted quickly to glucose and used for energy or stored as fat. "When we are eating, blood sugar--and insulin production--goes up. When we sleep or fast, it goes down," he said.
The process is not so simple with fructose, he noted. "In order for fructose to be metabolized, the body has to create both fasted and fed conditions. The liver is really busy when you eat a lot of fructose."
Because, unlike glucose, fructose metabolism occurs mainly in the liver, Nakamura wanted to gain a complete picture of gene expression in the liver during fructose metabolism.
In Nakamura's study, 24 rats were fed either a 63 percent glucose or fructose diet four hours a day for two weeks; at the end of this period, half the animals fasted for 24 hours before the scientists performed a gene expression analysis; the other half were examined at the end of a four-hour feeding.
Fructose feeding not only induced a broader range of genes than had previously been identified, there were simultaneous increases in glycogen (stored glucose) and triglycerides in the liver.
"To our surprise, a key regulatory enzyme involved in the breakdown of glucose was about two times higher in the fructose-fed group than in the glucose-fed group," Nakamura said.
The study also suggests that a protein called carbohydrate response element binding protein is responsible for the fructose effect on certain genes that trigger the production of fat, he said.
"We're continuing to assess the risk of fructose insulin resistance and the consequent risk for development of diabetes," he said.
University of Illinois at Urbana-Champaign
Fructose metabolism by the brain increases food intake and obesity
The journal Biochemical and Biophysical Research Communications (http://www.elsevier.com/locate/ybbrc) (BBRC), published by Elsevier, will publish an important review this week online, by M. Daniel Lane and colleagues at Johns Hopkins, building on the suggested link between the consumption of fructose and increased food intake, which may contribute to a high incidence of obesity and Type 2 diabetes.
More Fructose Metabolism Current Events and Fructose Metabolism News Articles
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Clinical and metabolic aspects of fructose: Papers presented at a symposium in Helsinki, Jan. 20-22, 1972 (Acta medica Scandinavia. Supplementum) by E Nikkilä (Author) | |
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The Sugar Fix: The High-Fructose Fallout That Is Making You Fat and Sick by Richard J Johnson (Author), Timothy Gower (Author) WHAT YOU DON'T KNOW ABOUT FRUCTOSE AND HFCS COULD KILL YOU Cutting back on the fructose in your diet could save your life -- and shrink your waistline. Table sugar and high-fructose corn syrup (HFCS) -- the primary sources of fructose -- are staples of our food supply, and are even found in foods that aren't necessarily sweet, like breads, soups, ketchup, and salad dressing. These sweeteners are linked to health problems such as obesity, diabetes, and joint and abdominal pain. They may also increase your risk for liver and kidney diseases, premature aging, and certain types of cancer. THE SUGAR FIX OFFERS A REAL SOLUTION FOR LOSING WEIGHT AND TRANSFORMING YOUR HEALTH -- TODAY The Low-Fructose Diet: Reduce your consumption of fructose by up to one-half the amount in... |
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Control of Fructose Metabolism in the Perfused Liver by Leif Sestoft (Author) | |
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The metabolism of fructose by the eviscerated rat by Roger Minske Reinecke (Author) | |
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Dietary sugars in health and disease: I. Fructose ; prepared for Bureau of Foods, Food and Drug Administration, Department of Health, Education, and Welfare ... under contract number FDA 223-75-2090 by K. K Kimura (Author) | |
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Dietary sugars in health and disease, I. fructose by K. K Kimura (Author) | |
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The Sugar Fix: The High-Fructose Fallout That Is Making You Fat a by Richard J Johnson (Author), Timothy Gower (Author) WHAT YOU DON'T KNOW ABOUT FRUCTOSE AND HFCS COULD KILL YOU Cutting back on the fructose in your diet could save your life -- and shrink your waistline. Table sugar and high-fructose corn syrup (HFCS) -- the primary sources of fructose -- are staples of our food supply, and are even found in foods that aren't necessarily sweet, like breads, soups, ketchup, and salad dressing. These sweeteners are linked to health problems such as obesity, diabetes, and joint and abdominal pain. They may also increase your risk for liver and kidney diseases, premature aging, and certain types of cancer. THE SUGAR FIX OFFERS A REAL SOLUTION FOR LOSING WEIGHT AND TRANSFORMING YOUR HEALTH -- TODAY The Low-Fructose Diet: Reduce your consumption of fructose by up to one-half the amount in... |
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Interactive effects of naphthalene treatment and the onset of vitellogenesis on energy metabolism in liver and gonad, and plasma steroid hormones of rainbow ... Biochemistry and Physiology, Part C] by A. Tintos (Author), M. Gesto (Author), R. Alvarez (Author), J.M. Miguez (Author), Soen (Author) This digital document is a journal article from Comparative Biochemistry and Physiology, Part C, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: The purpose of the study was to assess in female fish the possible interaction between treatment with a polycyclic aromatic hydrocarbon (PAH) like naphthalene and the onset of vitellogenesis. In a first experiment, female rainbow trout (Oncorhynchus mykiss) at stages 2-3 (previtellogenesis) or 4 (early vitellogenesis) were intraperitoneally injected (2 @ml g^-^1) with vegetable oil alone (control) or containing naphthalene (50 mg kg^-^1) to be sampled 3 h later. A second experiment was... |
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Metabolic Effects Of Dietary Fructose by Sheldon Reiser (Author), Judith Hallfrisch (Author) | |
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Fructose-2,6-Bisphosphate by Simon J. Pilkis (Author) This reference volume follows the Fructose-2, 6-P2 story from its discovery in 1980 to current studies on the enzyme systems responsible for its synthesis and degradation. The book begins with a historical perspective on the discovery of the compound and then proceeds to its chemistry and number of derivatives. It includes a detailed treatment of the role of the compound in the regulation of carbohydrate metabolism in various tissues and organisms. A portion of this work is devoted to characterization of the enzyme activities responsible for its synthesis and degradation. This detailed, yet comprehensive work is helpful for all biochemists, experimental biologists, and biophysicists. |
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