فروکتوز

فروکتوز مونوساکاریدی شش‌کربنه است. فرمول شیمیایی آن C6H۱۲O۶ بوده لذا ایزومر گلوکز و گالاکتوز است.
این کتوز، یکی از سه سوخت اصلی بدن است. نام دیگر آن لولز است و در تمامی میوه‌های شیرین مانند انگور یافت می‌شود. همچنین زنبورها طی فرآیندی با ترشح آنزیم‌هایی مانند دیاستاز نکتار (شهدهای گیاهی) جمع آوری شده را فرآوری می‌کنند و قندهای نکتار را (مانند ساکارز) به فروکتوز و گلوکز تبدیل می‌کنند. عسل حاصله حاوی حدودا" ۳۴٪ فروکتوز می‌باشد. فروکتوز قند مفیدی است که از بروز بعضی بیماری‌های مزمن جلوگیری می‌کند. مصرف فروکتوز باعث کاهش ترشح انسولین از سلول‌های بتای لوزالمعده می‌شود.[نیازمند منبع]
خواص فروکتوز [ویرایش]
خواص فروکتوز عبارتند از: شیرینی آن ۷/۱ برابر شکر است، با استفاده از فرآوری مخلوطی از گلوکز و فروکتوز شربت غنی از فروکتوز یا HFS با غلظت‌های متفاوت (معمولا" در سه غلظت ۴۲٪، ۵۵٪ و ۹۰٪ فروکتوز) تولید می‌گردد که در بهبود افراد مبتلا به دیابت مفید است. همچنین بر خلاف ساکارز نیازی به شکسته شدن در بدن ندارد و میتواند مستقیما در روده جذب شود. فروکتوز در تمامی موارد استفاده از شکر می‌تواند جایگزین آن شود.[نیازمند منبع]
از ویکی پدیا
قس
Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847.[3] Pure, dry fructose is a very sweet, white, odorless, crystalline solid and is the most water-soluble of all the sugars.[4] From plant sources, fructose is found in honey, tree and vine fruits, flowers, berries and most root vegetables. In plants, fructose may be present as the monosaccharide and/or as a component of sucrose. Commercially, fructose is usually derived from sugar cane, sugar beets and corn and there are three commercially important forms. Crystalline fructose is the monosaccharide, dried and ground, and of high purity. High-fructose corn syrup (HFCS) is a mixture of glucose and fructose as monosaccharides. Sucrose is the third form. All forms of fructose, including fruits and juices, are commonly added to foods and drinks for palatability, taste enhancement and improved browning of some foods, such as baked goods.
About 240,000 tons of crystalline fructose are produced annually.[5]
Contents [show]
[edit]Chemical properties



Figure 1: Relationship between the acyclic and the cyclic (hemiketal) isomers of fructose.


d- and l-isomers of fructose (open-chain form)
Fructose is a 6-carbon polyhydroxyketone. It is an isomer of glucose; i.e., both have the same molecular formula (C6H12O6) but they differ structurally. Crystalline fructose adopts a cyclic six-membered structure owing to the stability of its hemiketal and internal hydrogen-bonding. This form is formally called D-fructopyranose. In solution, fructose exists as an equilibrium mixture of 70% fructopyranose and about 22% fructofuranose, as well as small amounts of three other forms, including the acyclic structure.[6]
[edit]Reactions
[edit]Fructose and fermentation
Fructose may be anaerobically fermented by yeast or bacteria.[7] Yeast enzymes convert sugar (glucose, or fructose) to ethanol and carbon dioxide. The carbon dioxide released during fermentation will remain dissolved in water, where it will reach equilibrium with carbonic acid, unless the fermentation chamber is left open to the air. The dissolved carbon dioxide and carbonic acid produce the carbonation in bottle fermented beverages.[8]
[edit]Fructose and Maillard reaction
Fructose undergoes the Maillard reaction, non-enzymatic browning, with amino acids. Because fructose exists to a greater extent in the open-chain form than does glucose, the initial stages of the Maillard reaction occurs more rapidly than with glucose. Therefore, fructose potentially may contribute to changes in food palatability, as well as other nutritional effects, such as excessive browning, volume and tenderness reduction during cake preparation, and formation of mutagenic compounds.[9]
[edit]Dehydration
Fructose readily dehydrates to give hydroxymethylfurfural ("HMF"). This process may in the future be part of a low-cost, carbon-neutral system to produce replacements for petrol and diesel from plantations.[10]
[edit]Physical and functional properties

[edit]Relative sweetness
The primary reason that fructose is used commercially in foods and beverages, besides its low cost, is its high relative sweetness. It is the sweetest of all naturally occurring carbohydrates. Fructose is generally regarded as being 1.73 times as sweet as sucrose.[11][12] However, it is the 5-ring form of fructose that is sweeter; the 6-ring form tastes about the same as usual table sugar. Warming fructose leads to formation of the 6-ring form.[13]


Figure 2: Relative sweetness of sugars and sweeteners.
The sweetness of fructose is perceived earlier than that of sucrose or dextrose, and the taste sensation reaches a peak (higher than that of sucrose) and diminishes more quickly than that of sucrose. Fructose can also enhance other flavors in the system.[11]
[edit]Sweetness synergy
Fructose exhibits a sweetness synergy effect when used in combination with other sweeteners. The relative sweetness of fructose blended with sucrose, aspartame, or saccharin is perceived to be greater than the sweetness calculated from individual components.[14]
[edit]Fructose solubility and crystallization
Fructose has higher solubility than other sugars as well as other sugar alcohols. Fructose is, therefore, difficult to crystallize from an aqueous solution.[11] Sugar mixes containing fructose, such as candies, are softer than those containing other sugars because of the greater solubility of fructose.[15]
[edit]Fructose hygroscopicity and humectancy
Fructose is quicker to absorb moisture and slower to release it to the environment than sucrose, dextrose, or other nutritive sweeteners.[14] Fructose is an excellent humectant and retains moisture for a long period of time even at low relative humidity (RH). Therefore, fructose can contribute to improved quality, better texture, and longer shelf life to the food products in which it is used.[11]
[edit]Freezing point
Fructose has a greater effect on freezing point depression than disaccharides or oligosaccharides, which may protect the integrity of cell walls of fruit by reducing ice crystal formation. However, this characteristic may be undesirable in soft-serve or hard-frozen dairy desserts.[11]
[edit]Fructose and starch functionality in food systems
Fructose increases starch viscosity more rapidly and achieves a higher final viscosity than sucrose because fructose lowers the temperature required during gelatinizing of starch, causing a greater final viscosity.[16]
Many artificial sweeteners are not suitable for home-baking, but, with a little adjustment, many traditional recipes can be prepared using fructose.[17]
[edit]Food sources



Crystalline fructose
Natural sources of fructose include fruits, vegetables (including sugar cane), and honey.[18] Fructose is often further concentrated from these sources. The highest dietary sources of fructose, besides pure crystalline fructose, are foods containing table sugar (sucrose), high-fructose corn syrup, agave nectar, honey, molasses, maple syrup, and fruit juices, as these have the highest percentages of fructose (including fructose in sucrose) per serving compared to other common foods and ingredients. Fructose exists in foods either as a free monosaccharide or bound to glucose as sucrose, a disaccharide. Fructose, glucose, and sucrose may all be present in a food; however, different foods will have varying levels of each of these three sugars.
The sugar contents of common fruits and vegetables are presented in Table 1. In general, in foods that contain free fructose, the ratio of fructose to glucose is approximately 1:1; that is, foods with fructose usually contain about an equal amount of free glucose. A value that is above 1 indicates a higher proportion of fructose to glucose, and below 1 a lower proportion. Some fruits have larger proportions of fructose to glucose compared to others. For example, apples and pears contain more than twice as much free fructose as glucose, while for apricots the proportion is less than half as much fructose as glucose.
Apple and pear juices are of particular interest to pediatricians because the high concentrations of free fructose in these juices can cause diarrhea in children. The cells (enterocytes) that line children's small intestines have less affinity for fructose absorption than for glucose and sucrose.[19] Unabsorbed fructose creates higher osmolarity in the small intestine, which draws water into the gastrointestinal tract, resulting in osmotic diarrhea. This phenomenon is discussed in greater detail in the Health Effects section.
Table 1 also shows the amount of sucrose found in common fruits and vegetables. Sugarcane and sugar beet have a high concentration of sucrose, and are used for commercial preparation of pure sucrose. Extracted cane or beet juice is clarified, removing impurities; and concentrated by removing excess water. The end product is 99.9% pure sucrose. Sucrose-containing sugars include common table white granulated sugar and powdered sugar, as well as brown sugar.[20]
Table 1. Sugar content of selected common plant foods (g/100g)[21]
Food Item Total
Carbohydrate
Total
Sugars Free
Fructose Free
Glucose Sucrose Fructose/
Glucose
Ratio Sucrose
as a % of
Total Sugars
Fruits
Apple 13.8 10.4 5.9 2.4 2.1 2.0 19.9
Apricot 11.1 9.2 0.9 2.4 5.9 0.7 63.5
Banana 22.8 12.2 4.9 5.0 2.4 1.0 20.0
Fig, dried 63.9 47.9 22.9 24.8 0.07 0.93 0.001
Grapes 18.1 15.5 8.1 7.2 0.2 1.1 1.0
Peach 9.5 8.4 1.5 2.0 4.8 0.9 56.7
Pear 15.5 9.8 6.2 2.8 0.8 2.1 8.0
Pineapple 13.1 9.9 2.1 1.7 6.0 1.1 60.8
Plum 11.4 9.9 3.1 5.1 1.6 0.66 0.16
Vegetables
Beet, Red 9.6 6.8 0.1 0.1 6.5 1.0 96.2
Carrot 9.6 4.7 0.6 0.6 3.6 1.0 70.0
Corn, Sweet 19.0 6.2 1.9 3.4 0.9 0.61 15.0
Red Pepper, Sweet 6.0 4.2 2.3 1.9 0.0 1.2 0.0
Onion, Sweet 7.6 5.0 2.0 2.3 0.7 0.9 14.3
Sweet Potato 20.1 4.2 0.7 1.0 2.5 0.9 60.3
Yam 27.9 0.5 tr tr tr na tr
Sugar Cane 13 - 18 0.2 – 1.0 0.2 – 1.0 11 - 16 1.0 100
Sugar Beet 17 - 18 0.1 – 0.5 0.1 – 0.5 16 - 17 1.0 100
All data with a unit of g (gram) are based on 100 g of a food item. The fructose / glucose ratio is calculated by dividing the sum of free fructose plus half sucrose by the sum of free glucose plus half sucrose.
Fructose is also found in the synthetically manufactured sweetener, high-fructose corn syrup (HFCS). Hydrolyzed corn starch is used as the raw material for production of HFCS. Through the enzymatic treatment, glucose molecules are converted into fructose.[20] There are three types of HFCS, each with a different proportion of fructose: HFCS-42, HFCS-55, and HFCS-90. The number for each HFCS corresponds to the percentage of synthesized fructose present in the syrup. HFCS-90 has the highest concentration of fructose, and is typically used to manufacture HFCS-55; HFCS-55 is used as sweetener in soft drinks, whereas HFCS-42 is used in many processed foods and baked goods.
[edit]Carbohydrate content of commercial sweeteners (percent)
Sugar Fructose Glucose Sucrose (Fructose-Glucose) Other sugars
Granulated sugar 0 0 100 0
Brown sugar 1 1 97 1
HFCS-42 42 53 0 5
HFCS-55 55 41 0 4
HFCS-90 90 5 0 5
Honey 50 44 1 5
Maple syrup 1 4 95 0
Molasses 23 21 53 3
Corn syrup 0 35 0 0
Data obtained from Kretchmer, N. & Hollenbeck, CB (1991). Sugars and Sweeteners, Boca Raton, FL: CRC Press, Inc.[20] for HFCS, and USDA for fruits and vegetables and the other refined sugars.[21]
Cane and beet sugars have been used as the major sweetener in food manufacturing for centuries. However, with the development of HFCS, a significant shift occurred in the type of sweetener consumption. As seen in Figure 3, this change happened in the 1970s. Contrary to the popular belief, however, with the increase of HFCS consumption, the total fructose intake has not dramatically changed. Granulated sugar is 99.9% pure sucrose, which means that it has equal ratio of fructose to glucose. The most commonly used forms of HFCS, HFCS-42 and HFCS-55, have a roughly equal ratio of fructose to glucose, with minor differences. HFCS has simply replaced sucrose as a sweetener. Therefore, despite the changes in the sweetener consumption, the ratio of glucose to fructose intake has remained relatively constant.[22]


Figure 3: Adjusted consumption of refined sugar per capita in the U.S.
[edit]Fructose digestion and absorption in humans

Fructose exists in foods either as a monosaccharide (free fructose) or as a unit of a disaccharide (sucrose). Free fructose is absorbed directly by the intestine. When fructose is consumed in the form of sucrose, it is digested (broken down) and then absorbed as free fructose. As sucrose comes into contact with the membrane of the small intestine, the enzyme sucrase catalyzes the cleavage of sucrose to yield one glucose unit and one fructose unit, which are then each absorbed. After absorption it enters the hepatic portal vein and is directed toward the liver.


Figure 4: Hydrolysis of sucrose to glucose and fructose by sucrase.
The mechanism of fructose absorption in the small intestine is not completely understood. Some evidence suggests active transport, because fructose uptake has been shown to occur against a concentration gradient.[23] However, the majority of research supports the claim that fructose absorption occurs on the mucosal membrane via facilitated transport involving GLUT5 transport proteins. Since the concentration of fructose is higher in the lumen, fructose is able to flow down a concentration gradient into the enterocytes, assisted by transport proteins. Fructose may be transported out of the enterocyte across the basolateral membrane by either GLUT2 or GLUT5, although the GLUT2 transporter has a greater capacity for transporting fructose, and, therefore, the majority of fructose is transported out of the enterocyte through GLUT2.


Figure 5: Intestinal sugar transport proteins.
[edit]Capacity and rate of absorption
The absorption capacity for fructose in monosaccharide form ranges from less than 5 g to 50 g and adapts with changes in dietary fructose intake. Studies show the greatest absorption rate occurs when glucose and fructose are administered in equal quantities.[24] When fructose is ingested as part of the disaccharide sucrose, absorption capacity is much higher because fructose exists in a 1:1 ratio with glucose. It appears that the GLUT5 transfer rate may be saturated at low levels, and absorption is increased through joint absorption with glucose.[25] One proposed mechanism for this phenomenon is a glucose-dependent cotransport of fructose. In addition, fructose transfer activity increases with dietary fructose intake. The presence of fructose in the lumen causes increased mRNA transcription of GLUT5, leading to increased transport proteins. High-fructose diets[vague] have been shown to increase abundance of transport proteins within 3 days of intake.[26]
[edit]Malabsorption
Main article: Fructose malabsorption
Several studies have measured the intestinal absorption of fructose using hydrogen breath test.[27][28][29][30] These studies indicate that fructose is not completely absorbed in the small intestine. When fructose is not absorbed in the small intestine, it is transported into the large intestine, where it is fermented by the colonic flora. Hydrogen is produced during the fermentation process and dissolves into the blood of the portal vein. This hydrogen is transported to the lungs, where it is exchanged across the lungs and is measurable by the hydrogen breath test. The colonic flora also produces carbon dioxide, short-chain fatty acids, organic acids, and trace gases in the presence of unabsorbed fructose.[31] The presence of gases and organic acids in the large intestine causes gastrointestinal symptoms such as bloating, diarrhea, flatulence, and gastrointestial pain[27] Exercise immediately after consumption can exacerbate these symptoms by decreasing transit time in the small intestine, resulting in a greater amount of fructose emptied into the large intestine.[32]
[edit]Fructose metabolism

All three dietary monosaccharides are transported into the liver by the GLUT2 transporter.[33] Fructose and galactose are phosphorylated in the liver by fructokinase (Km= 0.5 mM) and galactokinase (Km = 0.8 mM). By contrast, glucose tends to pass through the liver (Km of hepatic glucokinase = 10 mM) and can be metabolised anywhere in the body. Uptake of fructose by the liver is not regulated by insulin. However, insulin is capable of increasing the abundance and functional activity of GLUT5 in skeletal muscle cells.[34]
[edit]Fructolysis
Main article: fructolysis
The initial catabolism of fructose is sometimes referred to as fructolysis, in analogy with glycolysis, the catabolism of glucose. In fructolysis, the enzyme fructokinase initially produces fructose 1-phosphate, which is split by aldolase B to produce the trioses dihydroxyacetone phosphate and glyceraldehyde [2]. Unlike glycolysis, in fructolysis the triose glyceraldehyde lacks a phosphate group. A third enzyme, triokinase, is therefore required to phosphorylate glyceraldehyde, producing glyceraldehyde-3-phosphate. The resulting trioses are identical to those obtained in glycolysis and can enter the gluconeogenic pathway for glucose or glycogen synthesis, or be further catabolized through the lower glycolytic pathway to pyruvate.
[edit]Metabolism of fructose to DHAP and glyceraldehyde
The first step in the metabolism of fructose is the phosphorylation of fructose to fructose 1-phosphate by fructokinase, thus trapping fructose for metabolism in the liver. Fructose 1-phosphate then undergoes hydrolysis by aldolase B to form DHAP and glyceraldehydes; DHAP can either be isomerized to glyceraldehyde 3-phosphate by triosephosphate isomerase or undergo reduction to glycerol 3-phosphate by glycerol 3-phosphate dehydrogenase. The glyceraldehyde produced may also be converted to glyceraldehyde 3-phosphate by glyceraldehyde kinase or converted to glycerol 3-phosphate by glyceraldehyde 3-phosphate dehydrogenase. The metabolism of fructose at this point yields intermediates in the gluconeogenic and fructolytic pathways leading to glycogen synthesis as well as fatty acid and triglyceride synthesis.
[edit]Synthesis of glycogen from DHAP and glyceraldehyde 3 phosphate
The resultant glyceraldehyde formed by aldolase B then undergoes phosphorylation to glyceraldehyde 3-phosphate. Increased concentrations of DHAP and glyceraldehyde 3-phosphate in the liver drive the gluconeogenic pathway toward glucose and subsequent glycogen synthesis.[35] It appears that fructose is a better substrate for glycogen synthesis than glucose and that glycogen replenishment takes precedence over triglyceride formation.[citation needed] Once liver glycogen is replenished, the intermediates of fructose metabolism are primarily directed toward triglyceride synthesis.[citation needed]


Figure 6: Metabolic conversion of fructose to glycogen in the liver.
[edit]Synthesis of triglyceride from DHAP and glyceraldehyde 3 phosphate
Carbons from dietary fructose are found in both the free fatty acid and glycerol moieties of plasma triglycerides. High fructose consumption can lead to excess pyruvate production, causing a buildup of Krebs cycle intermediates.[36] Accumulated citrate can be transported from the mitochondria into the cytosol of hepatocytes, converted to acetyl CoA by citrate lyase and directed toward fatty acid synthesis.[36][37] Additionally, DHAP can be converted to glycerol 3-phosphate as previously mentioned, providing the glycerol backbone for the triglyceride molecule.[37] Triglycerides are incorporated into very low density lipoproteins (VLDL), which are released from the liver destined toward peripheral tissues for storage in both fat and muscle cells.


Figure 7: Metabolic conversion of fructose to triglyceride in the liver.
[edit]Potential health effects

[edit]Digestion
Fructose absorption occurs in the small intestine via the GLUT-5[38] (fructose only) transporter, and the GLUT2 transporter, for which it competes with glucose and galactose. Over-consumption of fructose, inhibition of GLUT2 by other phytochemicals, such as flavonoids,[39] or other issues, may result in unabsorbed fructose being carried into the large intestine, where, like any sugar, it may provide nutrients for the existing gut flora.
[edit]Metabolism
In a 2012 meta-analysis of controlled feeding clinical trials, fructose was not an independent factor for weight gain, but rather the added calories from over-consumption contributed to added weight.[40]
Excess fructose consumption has been hypothesized to be a cause of insulin resistance, obesity,[41] elevated LDL cholesterol and triglycerides, leading to metabolic syndrome.[42] In preliminary research, fructose consumption was correlated with obesity.[43][44] A study in mice showed that a high fructose intake may increase adiposity.[45]
Although all simple sugars have nearly identical chemical formulae, each has distinct chemical properties. This can be illustrated with pure fructose. A journal article reports that, "...fructose given alone increased the blood glucose almost as much as a similar amount of glucose (78% of the glucose-alone area)".[46][47][48][48][49]
One study concluded that fructose "produced significantly higher fasting plasma triacylglycerol values than did the glucose diet in men" and "...if plasma triacylglycerols are a risk factor for cardiovascular disease, then diets high in fructose may be undesirable".[50]
Fructose is a reducing sugar, as are all monosaccharides. The spontaneous chemical reaction of simple sugar molecules binding to proteins is known as glycation. Showing potential cause of skin and bone damage in a rat model of diabetes, investigators suggested "that long-term fructose consumption negatively affects the aging process."[51] Another study using human proteins showed that the glycation caused by fructose appears to be equivalent to glucose and so does not seem to be a better answer for diabetes for this reason alone, save for the smaller quantities required to achieve equivalent sweetness in some foods. It also found evidence for glycation of human lens proteins caused by fructose.[52]
[edit]Compared to sucrose
Studies that have compared high-fructose corn syrup (an ingredient in nearly all soft drinks sold in the US) to sucrose (common table sugar) find that most measured short term physiological effects are equivalent.[dubious – discuss]; however, studies that compare the long term effects between sucrose and fructose have yet to be conducted. For instance, Melanson et al. (2006), studied the short term effects of HFCS and sucrose-sweetened drinks on blood glucose, insulin, leptin, and ghrelin levels. They found no significant differences in any of these parameters.[53] This is not surprising since sucrose is a disaccharide that digests to 50% fructose and 50% glucose, whereas the high-fructose corn syrup most commonly used on soft drinks is 55% fructose and 45% glucose. The difference between the two lies in the fact that HFCS contains little sucrose, the fructose and glucose being independent moieties. Even so, Melanson et. al found that "Longer-term studies on connections between HFCS, potential mechanisms, and body weight have not been conducted".
Fructose is often recommended for diabetics because it does not trigger the production of insulin by pancreatic β cells, probably because β cells have low levels of GLUT5.[54][55][56] Fructose has a very low glycemic index of 19 ± 2, compared with 100 for glucose and 68 ± 5 for sucrose.[57] Fructose is also seventy-three percent sweeter than sucrose (see relative sweetness) at room temperature, so diabetics can use less of it. Studies show that fructose consumed before a meal may even lessen the glycemic response of the meal.[58]
[edit]Liver function
While a few other tissues (e.g., sperm cells[59] and some intestinal cells) do use fructose directly, fructose is metabolized primarily in the liver.[60]
Compared with consumption of high glucose beverages, drinking high fructose beverages with meals results in lower circulating insulin and leptin levels, and higher ghrelin levels after the meal.[61] Since leptin and insulin decrease appetite and ghrelin increases appetite, some researchers suspect that eating large amounts of fructose increases the likelihood of weight gain.[62]
Excessive fructose consumption may contribute to the development of non-alcoholic fatty liver disease.[63]
[edit]Gout
A 2008 study found a substantial risk of incident gout associated with the consumption of fructose or fructose rich foods.[64] Cases of gout have risen in recent years, despite commonly being thought of as a Victorian disease, and it is suspected that the fructose found in soft drinks (e.g., carbonated beverages) and other sweetened drinks is the reason for this.[65][66]
[edit]Glycemic index
Because fructose is metabolized in the liver to glucose, fructose has the lowest glycemic index (GI = 19) of all the natural sugars and may be recommended for use by diabetics. In comparison, ordinary table sugar (sucrose, which is half fructose) has a GI of 65 and honey (usually about 50% fructose content) has a GI of 55. Due to the potential that excessive consumption of fructose may be a factor in some diseases, including metabolic syndrome and insulin resistance,[67] products containing high contents of fructose may be discouraged.
[edit]See also

Tagatose
Inverted sugar
DMF (potential fructose-based biofuel)
Fructose intolerance
Fructose malabsorption
Fructan (fructose polymer)
Galactose
Glucose
Glycation
High fructose corn syrup
Hyperuricemia
Seliwanoff's test
Sucrose
Sugars in wine
Agave nectar
[edit]References

^ Fructose - Merriam Webster dictionary
^ Levulose comes from the Latin word laevus, levo, "left side", levulose is the old word for the most occurring isomer of fructose. D-fructose rotate plane-polarised light to the left, hence the name.[1].
^ Fruton, J.S. Molecules of Life 1972, Wiley-Interscience
^ Hyvonen, L., & Koivistoinen, P (1982). "Fructose in Food Systems". In Birch, G.G. & Parker, K.J. Nutritive Sweeteners. London & New Jersey: Applied Science Publishers. pp. 133–144. ISBN 0-85334-997-5
^ Wolfgang Wach "Fructose" in Ullmann's Encyclopedia of Industrial Chemistry 2004, Wiley-VCH, Weinheim.doi:10.1002/14356007.a12_047.pub2
^ "Institute of Organic Chemistry".
^ McWilliams, Margaret. Foods: Experimental Perspectives, 4th Edition. ISBN 0-13-021282-2.
^ Keusch, P. "Yeast and Sugar- the Chemistry must be right".
^ Dills, WL (1993). "Protein fructosylation: Fructose and the Maillard reaction". Journal of Clinical Nutrition 58: 779–787.
^ Huber, G. W.; Iborra, S.; Corma, A. Chem. Rev. 2006, 106, 4044 - 4098. doi:10.1021/cr068360d
^ a b c d e Hanover, LM; White, JS (1993). "Manufacturing, composition, and application of fructose". Journal of Clinical Nutrition 58: 724s–732.
^ Oregon State University. "Sugar Sweetness". Last accessed May 5, 2008. http://food.oregonstate.edu/sugar/sweet.html Archived May 16, 2008 at the Wayback Machine
^ Fructose in our diet: http://www.medbio.info/Horn/Time%201-2/carbohydrate_metabolism.htm last visited 2008-12-28
^ a b Nabors, LO (2001). American Sweeteners. pp. 374–375.
^ McWilliams, Margaret (2001). Foods: Experimental Perspectives, 4th Edition. Upper Saddle River, NJ : Prentice Hall. ISBN 0-13-021282-2.
^ White, DC; Lauer GN (1990). "Predicting gelatinization temperature of starch/sweetener system for cake formulation by differential scanning calorimetry I. Development of a model". Cereal Foods Wold 35: 728–731.
^ Recipe Information for home baking at
^ Park, KY; Yetley AE (1993). "Intakes and food sources of fructose in the United States". American Journal of Clinical Nutrition 58 (5 Suppl): 737S–747S. PMID 8213605.
^ Riby, JE; Fujisawa T, Kretchmer N (1993). "Fructose absorption". American Journal of Clinical Nutrition 58 (5 Suppl): 748S–753S. PMID 8213606.
^ a b c Kretchmer, N; Hollenbeck CB (1991). Sugars and Sweeteners. CRC Press, Inc..
^ a b NAL USDA National Nutrient Database
^ Guthrie, FJ; Morton FJ (2000). "Food sources of added sweeteners in the diets of Americans". Journals of American Dietetic Association 100: 43–51. doi:10.1016/S0002-8223(00)00018-3.
^ Stipanuk, Marsha H (2006). Biochemical, Physiological, and Molecular Aspects of Human Nutrition, 2nd Edition. W.B. Saunders, Philadelphia, PA.
^ Fujisawa, T; Riby J, Kretchmer N (1991). "Intestinal absorption of fructose in the rat". Gastroenterology 101: 360–367. PMID 206591.
^ Ushijima, K; Fujisawa T, Riby J, Kretchmer N (1991). "Absorption of fructose by isolated small intestine of rats is via a specific saturable carrier in the absence of glucose and by the disaccharidase-related transport system in the presence of glucose". Journal of Nurtition 125 (8): 2156–2164. PMID 7643250.
^ Ferraris, R (2001). "Dietary and developmental regulation of intestinal sugar transport". Journal of Biochemistry 360 (Pt 2): 265–276. doi:10.1042/0264-6021:3600265. PMC 1222226. PMID 11716754.
^ a b Beyer, PL; Caviar EM, McCallum RW (2005). "Fructose intake at current levels in the United States may cause gastrointestinal distress in normal adults". J. Am. Diet. Assoc. 105 (10): 1559–1566. doi:10.1016/j.jada.2005.07.002. PMID 16183355.
^ Ravich, WJ; Bayless TM, Thomas, M (1983). "Fructose: incomplete intestinal absorption in humans". Gastroenterology 84 (1): 26–29. PMID 6847852.
^ Riby, JE; Fujisawa T, Kretchmer, N (1993). "Fructose absorption". American Journal of Clinical Nutrition 58 (5 Suppl): 748S–753S. PMID 8213606.
^ Rumessen, JJ; Gudman-Hoyer E (1986). "Absorption capacity of fructose in healthy adults. Comparison with sucrose and its constituent monosaccharides". Gut. 27 (10): 1161–1168. doi:10.1136/gut.27.10.1161. PMC 1433856. PMID 3781328.
^ Skoog, SM; Bharucha AE (2004). "Dietary fructose and gastrointestinal symptoms: a review". Am. J. Gastroenterol. 99 (10): 2046–50. doi:10.1111/j.1572-0241.2004.40266.x. PMID 15447771.
^ Fujisawa, T, T; Mulligan K, Wada L, Schumacher L, Riby J, Kretchmer N (1993). "The effect of exercise on fructose absorption". Am. J. Clin. Nutr. 58 (1): 75–9. PMID 8317393.
^ Quezada-Calvillo, R; Robayo CC, Nichols BL (2006). Carbohydrate Digestion and Absorption. Missouri: Saunders, Elsevier. pp. 182–185. ISBN 1-4160-0209-X.
^ Hajduch, E; Litherland GJ, Turban S, Brot-Laroche E, Hundal HS (Aug 2003). "Insulin regulates the expression of the GLUT5 transporter in L6 skeletal muscle cells". FEBS letters 549 (1–3): 77–82. doi:10.1016/S0014-5793(03)00773-7. PMID 12914929.
^ Parniak, MA; Kalant, N; Kalant N (1988). "Enhancement of glycogen concentrations in primary cultures of rat hepatocytes exposed to glucose and fructose". Biochemical Journal 251 (3): 795–802. PMC 1149073. PMID 3415647.
^ a b McGrane, MM (2006). Carbohydrate metabolism: Synthesis and oxidation. Missouri: Saunders, Elsevier. pp. 258–277. ISBN 1-4160-0209-X.
^ a b Sul, HS (2006). Metabolism of Fatty Acids, Acylglycerols, and Sphingolipids. Missouri: Saunders, Elsevier. pp. 450–467. ISBN 1-4160-0209-X.
^ Buchs, AE; Sasson S, Joost HG, Cerasi E. (1998). "Characterization of GLUT5 domains responsible for fructose transport". Endocrinology 139 (3): 827–31. doi:10.1210/en.139.3.827. PMID 9492009.
^ Kwon, Oran; et al (22). "Inhibition of the intestinal glucose transporter GLUT2 by flavonoids". FASEB Journal 21 (2): 366–377. doi:10.1096/fj.06-6620com. PMID 17172639.
^ Sievenpiper JL, de Souza RJ, Mirrahimi A, Yu ME, Carleton AJ, Beyene J, Chiavaroli L, Di Buono M, Jenkins AL, Leiter LA, Wolever TM, Kendall CW, Jenkins DJ (Feb 21 2012). "Effect of Fructose on Body Weight in Controlled Feeding Trials: A Systematic Review and Meta-analysis". Ann Intern Med 156(4): 291–304. PMID 22351714.
^ Elliott SS, Keim NL, Stern JS, Teff K, Havel PJ (2002). "Fructose, weight gain, and the insulin resistance syndrome". Am. J. Clin. Nutr. 76 (5): 911–22. PMID 12399260.
^ Basciano H, Federico L, Adeli K (2005). "Fructose, insulin resistance, and metabolic dyslipidemia". Nutrition & Metabolism 2 (5): 5. doi:10.1186/1743-7075-2-5. PMC 552336. PMID 15723702.
^ Lustig RH (2006). "Childhood obesity: behavioral aberration or biochemical drive? Reinterpreting the First Law of Thermodynamics". Nature clinical practice. Endocrinology & metabolism 2 (8): 447–58. doi:10.1038/ncpendmet0220. PMID 16932334.
^ Isganaitis E; Lustig RH (2005). "Fast food, central nervous system insulin resistance, and obesity". Arterioscler. Thromb. Vasc. Biol. 25 (12): 2451–62. doi:10.1161/01.ATV.0000186208.06964.91. PMID 16166564.
^ Jürgens H, Haass W, Castañeda TR et al (2005). "Consuming fructose-sweetened beverages increases body adiposity in mice". Obes. Res. 13 (7): 1146–56. doi:10.1038/oby.2005.136. PMID 16076983.
^ Hughes TA, Atchison J, Hazelrig JB, Boshell BR (1989). "Glycemic responses in insulin-dependent diabetic patients: effect of food composition". Am. J. Clin. Nutr. 49 (4): 658–66. PMID 2929488.
^ Wylie-Rosett, Judith; et al. (2004). "Carbohydrates and Increases in Obesity: Does the Type of Carbohydrate Make a Difference?". Obesity Res 12: 124S–129S. doi:10.1038/oby.2004.277. PMID 15601960.
^ a b Havel PJ (2001). "Peripheral signals conveying metabolic information to the brain: short-term and long-term regulation of food intake and energy homeostasis". Exp. Biol. Med. (Maywood) 226 (11): 963–77. PMID 11743131.
^ Dennison BA, Rockwell HL, Baker SL (1997). "Excess fruit juice consumption by preschool-aged children is associated with short stature and obesity". Pediatrics 99 (1): 15–22. PMID 8989331.
^ Bantle JP, Raatz SK, Thomas W, Georgopoulos A (2000). "Effects of dietary fructose on plasma lipids in healthy subjects". Am. J. Clin. Nutr. 72 (5): 1128–34. PMID 11063439.
^ Levi, B; Werman MJ (1998). Fulltext "Long-term fructose consumption accelerates glycation and several age-related variables in male rats. PMID 9732303". J Nutr 128 (9): 1442–9. PMID 9732303.
^ McPherson, JD; Shilton BH, Walton DJ (November 1988). "Role of fructose in glycation and cross-linking of proteins. PMID 132203". Biochemistry 27 (5): 1901–7. doi:10.1021/bi00406a016. PMID 3132203.
^ Melanson, K.; et al. (2006). "Eating Rate and Satiation". Obesity Society (NAASO) 2006 Annual Meeting, October 20–24,Hynes Convention Center, Boston, Massachusetts..
^ A. M. Grant, M. R. Christie, S. J. Ashcroft (August 1980). "Insulin Release from Human Pancreatic Islets in Vitro". Diabetologia 19 (2): 114–117. doi:10.1007/BF00421856. PMID 6998814.
^ D. L. Curry (1989). "Effects of Mannose and Fructose on the Synthesis and Secretion of Insulin". Pancreas 4 (1): 2–9. doi:10.1097/00006676-198902000-00002. PMID 2654926.
^ Y. Sato, T. Ito, N. Udaka et al (December 1996). "Immunohistochemical Localization of Facilitated-Diffusion Glucose Transporters in Rat Pancreatic Islets". Tissue Cell 28 (6): 637–643. doi:10.1016/S0040-8166(96)80067-X. PMID 9004533.
^ Kaye Foster-Powell, Susanna H. A. Holt, and Janette C. Brand-Miller (2002). "International Table of Glycemic Index and Glycemic Load Values: 2002". American Journal of Clinical Nutrition 76 (1): 5–56. PMID 12081815.
^ Patricia M. Heacock, Steven R. Hertzler and Bryan W. Wolf (2002). "Fructose Prefeeding Reduces the Glycemic Response to a High-Glycemic Index, Starchy Food in Humans". Journal of Nutrition 132 (9): 2601–2604. PMID 12221216.
^ Mann, T (1954). The Biochemistry of Semen. London: Methuen & Co; New York: John Wiley & Sons
^ Bray, George A. (2007). How bad is fructose?. American Journal of Clinical Nutrition
^ Teff, KL; Elliott SS, Tschöp M, Kieffer TJ, Rader D, Heiman M, Townsend RR, Keim NL, D'Alessio D, Havel PJ (June 2004). "Dietary fructose reduces circulating insulin and leptin, attenuates postprandial suppression of ghrelin, and increases triglycerides in women". J Clin Endocrinol Metab. 89 (6): 2963–72. doi:10.1210/jc.2003-031855. PMID 15181085.
^ Swan, Norman; Lustig, Robert H. "ABC Radio National, The Health Report, The Obesity Epidemic". Retrieved 2007-07-15.
^ Ouyang X, Cirillo P, Sautin Y et al (June 2008). "Fructose Consumption as a Risk Factor for Non-alcoholic Fatty Liver Disease". J. Hepatol. 48 (6): 993–9. doi:10.1016/j.jhep.2008.02.011. PMC 2423467. PMID 18395287.
^ Choi, Hyon K. and Curhan, Gary. "Soft drinks, fructose consumption, and the risk of gout in men: prospective cohort study". BMJ. Retrieved 5 December 2011.
^ "Gout surge blamed on sweet drinks". BBC News. 2008-02-01.
^ Johnson, Richard Joseph; Timothy Gower (2008). The Sugar Fix: The High-Fructose Fallout That is Making You Fat and Sick. US: Rodale. pp. 304. ISBN 1-59486-665-1.
^ Lim, Jung; Michele Mietus-Snyder, Annie Valente, Jean-Marc Schwarz and Robert H. Lustig (May 2010). "the role of fructose in the pathogenesis of naFlD and the metabolic syndrome". Nature reviews | gastroenterology & hepatology 7 (5): 251–264. doi:10.1038/nrgastro.2010.41.
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