Absence of a generalized disaccharide effect in adult female rats

Adult female Sprague-Dawley rats were either prefed ground nonpurified diet, starved 48 h, then refed a purified carbohydrate diet for 72 h or shifted from ground nonpurified diet directly to a purified carbohydrate diet for 72 h. Diets were formulated to contain 65% carbohydrate either as the disaccharides maltose or sucrose or as their respective monosaccharide equivalents glucose and invert sugar (glucose: fructose, 1:1). Alternations in hepatic glucose 6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and malic enzyme (ME) activities, relative liver size and food efficiency were determined. Rats starved and refed invert sugar had higher levels of G6PDH and ME than those red glucose, indicating a positive fructose effect. The greatest changes in hepatic enzyme activities were observed in rats consuming diets containing sucrose. Positive fructose and disaccharide effects were obtained with sucrose for all enzymes studied in both dietary shift and starve-refeed studies. No disaccharide effect was observed with maltose. In conclusion, females did not display a generalized disaccharide effect with either dietary shifting or starvation refeeding.     

Effects of starch, sucrose, fructose and glucose on chromium absorption and tissue concentrations in obese and lean mice

Forty-eight male genetically obese (OB) mice (C57BL/6J-OB) and 48 lean male littermates were randomly assigned within main plots (OB or lean) to one of eight diets. Diets were low chromium or supplemented with 1 mg chromium as CrCl3 per kg. Starch, sucrose, fructose or glucose comprised 50% of the diet, which met AIN recommendations except for chromium. Experimental diets and deionized water were available ad libitum for 26 d. Mice were fasted 10 h and were intubated 2 h before killing with 15 microCi of 51CrCl3 in a 25% carbohydrate solution (2 mg carbohydrate/g body wt) of either starch, sucrose, glucose or fructose corresponding to the diet previously fed. 51Cr concentrations were significantly higher in the blood, liver, spleen, epididymal fat pad, testes and femur of animals given their carbohydrate load as starch than in animals fed sucrose, fructose or glucose. Carbohydrate had a significant effect on chromium concentrations of testes, spleen, kidney and liver with values generally being higher with the starch diet. Chromium supplementation increased bone and kidney chromium concentrations and heart and muscle glycogen. These data indicate that the source of carbohydrate can alter chromium absorption and retention.     

Preexercise feedings of glucose, fructose or sucrose: effects on substrate depletion in rats

Male Wistar rats (n = 72) trained to run on a treadmill were fasted overnight and fed by gavage 3 ml unsupplemented water or a solution containing 2 g of glucose, fructose or sucrose 30 min prior to exercise. Six rats from each dietary group were killed after 0, 1 or 2 h of exercise. Blood glucose levels decreased in all groups over the 2-h exercise period; however, the largest decline in blood glucose was exhibited by the rats fed unsupplemented water (-32.1%), followed by those fed fructose (-26.9%), sucrose (-13.9%) and glucose (-8.3%). The water-fed control rats also had the largest increase in circulating free fatty acids (+215.4%), followed by those fed fructose (+120.8%), sucrose (+69.2%) and glucose (+57.5%). The fructose-fed animals exhibited the greatest depletion of liver glycogen and the smallest decline in soleus and red vastus lateralis muscle glycogen of the rats fed the different carbohydrates. The data indicate that exercise-induced changes in substrate levels can be modified by the type of carbohydrate given prior to exercise.     

Apparent inability of channel catfish to utilize dietary mono- and disaccharides as energy sources

Purified diets containing equivalent amounts of glucose, maltose, fructose, sucrose, corn starch and dextrin were fed to fingerling channel catfish (Icatalurus punctatus) to compare the growth responses to these various carbohydrates. The best growth response was achieved with dextrin and the next best with corn starch. Fish grew at the same rate when glucose, maltose or sucrose was the only dietary carbohydrate source. Dietary fructose resulted in the lowest growth rate. Feed efficiency and percent retained energy values followed the same pattern as growth rates. These data suggest that the catfish is apparently unable to utilize dietary mono- and disaccharides as energy sources. Oral carbohydrate tolerance tests using glucose, maltose, fructose, sucrose and dextrin were conducted with larger channel catfish. Oral glucose and maltose resulted in a persistent hyperglycemia indicative of a diabetic-like status. Fructose appeared to be poorly absorbed from the intestinal tract and did not appear to be converted to glucose. Oral administration of sucrose was followed by a gradual increase in plasma glucose, with no detectable fructose being absorbed until the 6-h period. Oral dextrin resulted in less than a two-fold increase in plasma glucose, which remained constant from 2 to 4 h after administration and then declined. These observations are consistent with the hypothesis that certain fishes, including the channel catfish, resemble diabetic animals by having insufficient insulin for maximum carbohydrate utilization.     

Nutritional assessment in humans and rats of leucrose [D-glucopyranosyl-alpha(1----5)-D-fructopyranose] as a sugar substitute

Leucrose [D-glucosyl-alpha(1----5)-D-fructopyranose], prepared by an enzyme-catalyzed transglycosidation from sucrose with greater than 99% purity, has previously been shown to be noncariogenic and was found in the present study to be apparently easily digestible when given to humans as a single oral dose of 100 g, or when fed to rats at a level of 35 g/kg body wt daily. Weanling rats fed a 25% leucrose diet grew as well as rats fed a diet containing 25% sucrose or corn starch. When 1 g of leucrose was given intravenously to adult rats, 70% of this disaccharide was excreted in the urine within 24 h, and feeding and drinking behavior of the rats was not altered. No adverse effects on their general health were observed. The substrate properties of leucrose for alpha-glucosidase from yeast and for carbohydrases from human jejunal mucosa were determined, and these data were then compared with those of maltose and sucrose. The cleavage rate of leucrose in vitro by human digestive carbohydrases was 31% that of maltose and 63% that of sucrose. Hydrogenated leucrose (leucritol) was cleaved 10 times slower, with a Michaelis constant close to that of leucrose. Blood glucose and fructose profiles in humans given leucrose per os tended to be lower than those in humans given sucrose, while insulin and C-peptide profiles were unaltered.     

Demonstration of a specific metabolic effect of dietary disaccharides in the rat.

Male Wistar rats were starved and refed diets containing either 40% carbohydrate as monosaccharides (glucose, fructose, invert sugar) or disaccharides (maltose, sucrose), or 42.2% carbohydrate as glucose. Induction of various liver enzymes and changes in total liver lipid levels by the different dietary sugars were studied. Liver enzymes measured included glucose-6-phosphate dehydrogenase (g6pd), 6-phosphogluconate dehydrogenase (6PGD), malic enzyme (ME), phosphofructokinase (PFK), L-alpha-glycerol phosphate dehydrogenase (LalphaGPD), pyruvate kinase (PK), citrate cleavage enzyme (CCE), acetyl CoA carboxylase (AcCoAC), and fatty acid synthetase (FAS). The responses in enzyme activity to diets containing glucose or invert sugar were used as the basal response. Enzyme responses to refeeding the carbohydrate diets fell into three categories: (1) enzyme activity increased both by the disaccharide configuration of the carbohydrate and by fructose (G6PD, PK, CCE, AcCoAC, FAS); (2) enzyme activity increased only by the disaccharide configuration of the carbohydrate (6PGD, ME); and (3) enzyme activity increased only by fructose (PFK, LalphaGPD). Total liver lipid level was increased both by the disaccharide configuration of the carbohydrate and by fructose. Refeeding diets containing equal molar amounts of glucose or maltose did not abolish the disaccharide effect. The data indicate that the disaccharide configuration of maltose and sucrose may have an effect at the gastrointestinal level, which causes an increased induction of certain enzymes in the liver.     

Effects of dietary carbohydrate on hepatic gluconeogenesis in BHE rats

The effects of feeding different carbohydrates on hepatic gluconeogenesis in BHE rats was studied. Three experiments were conducted that differed only in the aspects of gluconeogenesis examined. In experiment 1, gluconeogenesis and ketogenesis by hepatocytes isolated from 48-h starved rats were determined. In experiment 2, the activities of selected gluconeogenic enzymes were determined in starved and nonstarved rats. In experiment 3, the levels of the various metabolites of glycolysis and the citric acid cycle were determined in nonstarved rats. Rats were fed diets containing starch, maltose, glucose, sucrose or an equimolar mixture of glucose and fructose. In starved rats, gluconeogenesis was less in starch-fed rats than in rats fed any of the sugar diets. These same diet differences, with few exceptions, were also observed in ketogenesis. Glucose 6-phosphatase activity was lower in nonstarved rats fed starch and maltose than in rats fed glucose, sucrose, or glucose and fructose. These same nonstarved rats also had lower phosphoenolpyruvate carboxykinase and higher glutamate pyruvate transaminase activities than rats fed the other diets. In the starved rats, the diet differences were erased. Starved rats had lower activities of these gluconeogenic enzymes than nonstarved rats. Diet differences in the levels of the different metabolites in nonstarved rats were observed. The results show that dietary carbohydrate can influence gluconeogenesis. However, the mechanism of their effect is as yet unknown.     

The influence of various carbohydrates on the feeding pattern of rats fed zinc-deficient diets

When dextrin, maltose, sucrose, glucose, and fructose were used as a source of carbohydrate in a diet, the food intake of rats fed either a Zn-adequate or Zn-deficient diet was evaluated daily over 28 d. The average food intake of all groups of rats fed the Zn-deficient diet was significantly lower than that of the corresponding groups of Zn-adequate control rats. The food intake of the dextrin group was the highest under both Zn-deficient and Zn-adequate diets, and that of the fructose group was the lowest. All rats of the dextrin, maltose, sucrose, glucose, and fructose groups with the Zn-deficient status showed a characteristic cyclic variation in food intake and fitted well to a Cosinor curve. The values of the mesor, amplitude, and period of the food intake cycles showed significant differences among the groups. The higher intake of the glucose diet than the fructose diet of rats fed a Zn-deficient diet may be related to the different metabolisms of the carbohydrates used, from the comparison of the quantities consumed in the corresponding carbohydrates of Zn-adequate diets.     

Ability of juvenile white sturgeon (Acipenser transmontanus) to utilize different carbohydrate sources

Juvenile white sturgeon were fed isonitrogenous diets containing 27.2% glucose, fructose, maltose, sucrose, lactose, dextrin, raw corn starch or cellulose for 8 wk. Growth, body composition, plasma chemistry (with the exception of glucose), and liver glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49), malic enzyme (EC 1.1.1.40) and isocitrate dehydrogenase (ICDH, 1.1.1.42) activities of sturgeon were significantly (P less than 0.05) affected by the different dietary carbohydrate sources. Sturgeon fed either the maltose or glucose diets had the highest percent energy retained, followed by those fed either the dextrin, raw corn starch or sucrose diets, whereas those fed either the lactose, fructose or cellulose diets had the lowest. Sturgeon fed either the maltose or glucose diets were hyperlipidemic, having twice the amount of plasma total lipid, triacylglycerol and total cholesterol as fish fed the other carbohydrate sources. These two carbohydrate sources were also more lipogenic: maltose- or glucose-fed sturgeon had significantly higher body lipid and liver G6PDH, malic enzyme, and ICDH activities. The poor ability of sturgeon to utilize either sucrose or lactose appears to be due to low intestinal sucrase (EC 3.2.1.48) and lactase (EC 3.2.1.108) activities. Intestinal aminopeptidase (EC 3.4.11.11), maltase (EC 3.2.1.20), sucrase and lactase activities of sturgeon were not affected by feeding different carbohydrate sources for 8 wk.     

Effect of dietary carbohydrates on food efficiency and body composition in adult male rats during normal growth and during recovery from food restriction

Male Wistar rats about 8 to 9 weeks of age were fed diets which contained 43% of the calories as glucose, maltose, uncooked cornstarch, sucrose, or invert sugar. Half the animals in each dietary group were made to lose 37% of their initial body weights by food restriction and then allowed to eat their food ad libitum for 31 days (restricted-refed groups). The rest of the animals were fed ad libitum for 71 days (unrestricted groups). There were no dietary effects on food efficiency during recovery or in the percent body fat after recovery in the restricted-refed animals (ANOVA). However, the disaccharides produced a greater weight of body fat than starch or monosaccharides. In unrestricted animals, invert sugar, sucrose, and maltose were used with higher efficiency than starch or glucose. Rats fed the maltose diet ate 12% more food than did the animals fed glucose and had food energy efficiency and body fat percentages 62% greater than those eating the glucose diet. Maltose also produced similar differences compared to cornstarch. Although mean body fat percentages produced by sucrose or invert sugar feeding were greater than those caused by glucose and starch, the differences were not significant. Thus a fructose effect on body fat was not shown statistically.     

Various macronutrient intakes additively stimulate protein synthesis in liver and muscle of food-deprived chicks

We investigated the influence of refeeding food-deprived chicks with either protein, carbohydrate, fat or combinations thereof on the rates of liver and muscle protein synthesis. After 2 d of food-deprivation, chicks were given individual or mixed protein, carbohydrate and fat. At 30 min after refeeding, the protein fractional synthesis rate (K(s)) was measured by a large dose injection of L-[2,6-(3)H]phenylalanine. When chicks were food-deprived for 2 d, liver K(s) was 67% lower and muscle fractional synthesis rate was half that of well-fed controls. Upon refeeding starved chicks a complete diet, K(s) in the liver and muscle returned to the level of fed controls within 30 min. When food-deprived chicks were refed protein alone or two of the three macronutrients, liver and muscle K(s) were significantly higher than those in the starved group. There was no effect of refeeding with carbohydrate or fat alone. Plasma glucose concentration was significantly greater than in fed or starved groups in chicks refed the complete diet, carbohydrate or carbohydrate mixed with either protein or fat. Refeeding chicks with the various macronutrients did not affect the plasma insulin or insulin-like growth factor-I concentrations. These results suggest that intakes of individual macronutrients additively increase liver and muscle protein synthesis and that the acute increase in muscle protein synthesis after refeeding chicks diets containing the three macronutrients was mainly regulated by the change in ribosomal efficiency.     

Dietary effects on liver and muscle glycogen repletion in exhaustively exercised rats: energy composition and type of complex carbohydrates

Previous reports have indicated that administration of a glucose-citrate (G-C) drink after a bout of exhaustive exercise results in more effective glycogen repletion in liver and skeletal muscle in rats as compared with administration of glucose alone. The present studies report the effects of the energy pattern and the type of carbohydrates, dextrin or starch from rice, in diet given following the G-C drink after exercise, on further glycogen repletion in the tissues of rats. Rats were adapted to meal-feeding 3 times a day and trained with light swimming for 7 to 10 days. On the final day of experiments, rats received the G-C drink after 2 h of exhaustive swimming and were then fed on diets with different energy patterns or carbohydrate types. Results showed that a high-carbohydrate diet is more effective than a high-fat diet for further glycogen repletion in liver and skeletal muscle. In addition, dextrin was revealed to be superior to starch as a carbohydrate source in tissue glycogen repletion. As compared with the high-fat diet, the high-carbohydrate diet, however, resulted in a lower serum free fatty acid concentration 4 h after ingestion of food possibly by decreasing adipose tissue lipolysis.     

Stoppage of glycogenesis and "over-shoot" of induction of lipogenesis and its related enzyme activities in the liver of fasted-refed rats.

To elucidate the causes of changes of carbohydrate metabolic pathways, the time course of utilization of dietary [U-14C]sucrose and induction of enzyme activities in the livers of rats were investigated. Adult male rats of BHE strain were refed after a fast of 2 days. The nutritionally complete refeeding diet contained 60% sucrose as the only source of carbohydrate. [U-14C]Sucrose was included in the diet on either day 1 or day 2, or both of refeeding. During the first day of refeeding, the radioactivity was incorporated mainly into liver glycogen which rose to over 100 mg/g. During the second day, little 14C appeared in the liver glycogen, which decreased sharply while glucose-6-phosphatase activity increased. The glycogenic pathway thus appeared to be blocked. On the other hand, 14C incorporation in the liver fat was minimal during the first day, but was quite extensive during the second day of refeeding. The enhanced lipogenesis was accompanied by large increases of activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP-malic dehydrogenase. Results clearly indicate that the carbohydrate load in the liver of intact animals was initially metabolized by the glycogenic pathway. When glycogenesis stopped, carbohydrate was metabolized differently. The enhanced incorporation of [U-14C]sucrose into liver lipids indicates an increased formation of acetyl CoA and an accelerated formation and use of NADPH, probably from increasing dehydrogenase activities. Our data suggest that the blockage of synthesis of glycogen with the continuation of carbohydrate load was a primary cause in over-shooting induction of hepatic dehydrogenase activities and lipogenesis.     

Coffee extract attenuates changes in cardiovascular and hepatic structure and function without decreasing obesity in high-carbohydrate, high-fat diet-fed male rats

Coffee, a rich source of natural products, including caffeine, chlorogenic acid, and diterpenoid alcohols, has been part of the human diet since the 15th century. In this study, we characterized the effects of Colombian coffee extract (CE), which contains high concentrations of caffeine and diterpenoids, on a rat model of human metabolic syndrome. The 8-9 wk old male Wistar rats were divided into four groups. Two groups of rats were fed a corn starch-rich diet whereas the other two groups were given a high-carbohydrate, high-fat diet with 25% fructose in drinking water for 16 wk. One group fed each diet was supplemented with 5% aqueous CE for the final 8 wk of this protocol. The corn starch diet contained ~68% carbohydrates mainly as polysaccharides, whereas the high-carbohydrate, high-fat diet contained ~68% carbohydrates mainly as fructose and sucrose together with 24% fat, mainly as saturated and monounsaturated fat from beef tallow. The high-carbohydrate, high-fat diet-fed rats showed the symptoms of metabolic syndrome leading to cardiovascular remodeling and nonalcoholic fatty liver disease. CE supplementation attenuated impairment in glucose tolerance, hypertension, cardiovascular remodeling, and nonalcoholic fatty liver disease without changing abdominal obesity and dyslipidemia. This study suggests that CE can attenuate diet-induced changes in the structure and function of the heart and the liver without changing the abdominal fat deposition.     

Influence of dietary carbohydrates upon the metabolism of lipids and minerals in rabbits

Rabbits were fed purified diets containing either corn starch, sucrose, glucose or fructose as 39.5% of the caloric content, or were fed a commercial diet. At the end of the 12-week trial period, glucose tolerance tests did not reveal a difference by treatment, and males had a lower tolerance than females. The serum cholesterol concentrations of the various density lipoproteins varied by treatment as determined weekly; often the HDL cholesterol was higher in the rabbits fed corn starch, and the VLDL cholesterol was higher in the rabbits fed corn fructose. Cholelithiasis at the end of the trial was prevalent in rabbits fed sucrose, glucose or fructose, was infrequent in the rabbits fed corn starch, and was absent in the rabbits fed the commercial diet. Lipid and cholesterol concentrations in the liver were greater in the rabbits fed the purified diets than in those fed the commercial diet. Cholesterol concentration in the thoracic aorta was greater in the rabbits fed the commercial diet than in those fed the purified diet. Analyses of liver and kidneys for Cr, Mn, Cu and Zn revealed treatment differences only in the case of the kidneys where Cr concentration was greater in the kidneys when the commercial diet was fed.     

Substituting honey for refined carbohydrates protects rats from hypertriglyceridemic and prooxidative effects of fructose

Recent findings indicate that a high fructose diet has a prooxidant effect in rats compared with a starch diet. Because honey is rich in fructose, the aim of this study was to assess the effect of substituting honey for refined carbohydrates on lipid metabolism and oxidative stress. Rats were fed for 2 wk purified diets containing 65 g/100 g carbohydrates as wheat starch or a combination of fructose and glucose or a honey-based diet prepared by substituting honey for refined carbohydrates (n = 9/group). The same amount of fructose was provided by the honey and fructose diets. The hypertriglyceridemic effect of fructose was not observed when fructose was provided by honey. Compared with those fed starch, fructose-fed rats had a lower plasma alpha-tocopherol level, higher plasma nitrite and nitrate (NOx) levels and were less protected from lipid peroxidation as indicated by heart homogenate TBARS concentration. Compared with those fed fructose, honey-fed rats had a higher plasma alpha-tocopherol level, a higher alpha-tocopherol/triacylglycerol ratio, lower plasma NOx concentrations and a lower susceptibility of heart to lipid peroxidation. Further studies are required to identify the mechanism underlying the antioxidant effect of honey but the data suggest a potential nutritional benefit of substituting honey for fructose in the diet.     

Tracing metabolic routes of dietary carbohydrate and protein in rainbow trout (Oncorhynchus mykiss) using stable isotopes ([¹³C]starch and [¹⁵N]protein): effects of gelatinisation of starches and sustained swimming

Here we examined the use of stable isotopes, [13C]starch and [1?N]protein, as dietary tracers to study carbohydrate assimilation and distribution and protein utilisation, respectively, by rainbow trout (Oncorhynchus mykiss). The capacity of glucose uptake and use by tissues was studied, first, by varying the digestibility of carbohydrate-rich diets (30 % carbohydrate), using raw starch and gelatinised starch (GS) and, second, by observing the effects of two regimens of activity (voluntary swimming, control; sustained swimming at 1·3 body lengths/s, exercise) on the GS diet. Isotopic ratio enrichment (13C and 1?N) of the various tissue components (protein, lipid and glycogen) was measured in the liver, muscles, viscera and the rest of the fish at 11 and 24 h after a forced meal. A level of 30 % of digestible carbohydrates in the food exceeded the capacity of rainbow trout to use this nutrient, causing long-lasting hyperglycaemia that raises glucose uptake by tissues, and the synthesis of glycogen and lipid in liver. Total 13C recovered 24 h post-feeding in the GS group was lower than at 11 h, indicating a proportional increase in glucose oxidation, although the deposition of lipids in white muscle (WM) increased. Prolonged hyperglycaemia was prevented by exercise, since sustained swimming enhances the use of dietary carbohydrates, mainly through conversion to lipids in liver and oxidation in muscles, especially in red muscle (RM). Higher recoveries of total 15N for exercised fish at 24 h, mainly into the protein fraction of both RM and WM, provide evidence that sustained swimming improves protein deposition, resulting in an enhancement of the protein-sparing effect.     

Impairment of glucose tolerance in copper-deficient rats: dependency on the type of dietary carbohydrate

Copper deficiency was induced in weanling rats in order to study the possible interaction between the types of dietary carbohydrate and copper deficiency on glucose tolerance. Weanling male rats were fed copper-deficient or copper-supplemented diets containing either 62% starch, fructose or glucose. During week 5 the fructose portion of the copper-deficient diet was replaced (20 rats) by starch (10 rats) or glucose (10 rats). During the 9th week, an oral glucose tolerance test weas performed. Copper deficiency was associated with impaired glucose tolerance characterized by increased blood glucose and decreased insulin levels only in copper-deficient rats fed the monosaccharides fructose or glucose but not the polysaccharide starch. Changing the dietary carbohydrates in the copper-deficient diet from fructose to starch increased insulin levels and decreased blood glucose in response to the glycemic stress when compared to rats continuously fed fructose. Although both glucose and fructose feeding impaired the glucose tolerance, fructose was more diabetogenic. This could be demonstrated by some improvements in glucose tolerance when the copper-deficient rats were switched from the fructose to the glucose diet. The data indicate that copper deficiency per se does not impair glucose tolerance.     

Lipid metabolism in rats fed a diet rich in various carbohydrates. I. Results after I.P. injection of lipogenic precursors]

Male rats, Wistar CF strain, weighing 120 g at the beginning of the experiment, were fed during 7 months with one of the following diets, containing 72 p. 100 (w/w) carbohydrate: starch, fructose, glucose and sucrose. These diets were about 18% (w/w) in protein content and were conveniently balanced with respect to vitamins and mineral nutrients. After an overnight fast, the animals received by the i.p. way, 30 mn before their killing, one of the following lipogenic precursors: glucose (considered as the control treatment), fructose ethanol or acetate, thus forming 16 experimental groups. In their liver, heart and blood were determined the concentrations of 6 lipid compounds: triglycerides, non-esterified fatty acids, free, esterified and total cholesterol, phospholipide. a. The sucrose diet gave the heaviest animals, with a liver and heart which were the richest in triglyceride content. They had also the highest liver and blood cholesterol, but their blood phospholipid was the lowest. The starch diet also increased, compared to the glucose diet, liver and heart triglycerides and liver cholesterol. As regards the fructose diet, it had the same effects than the sucrose one in elevating liver weight, blood triglycerides and cholesterol; conversely, it lowered liver and chiefly heart triglycerides and increased blood phospholipide. The glucose diet was for almost all parameters the one which displayed the lowest values. b. Relative to the glucose injection, other ones increased liver triglycerides, cholesterol and phospholipids and non-esterified fatty acids of the 3 assayed tissues. We observed that some differences between the effects of two given injections varied according to the previous diet, e.g. the sucrose-fed rats had more liver triglycerides and cholesterol, more heart and blood cholesterol after i.p. fructose than after i.p. glucose, which was not the case for the starch-fed animals. The importance of liver esterification reactions, which are increased with a long-term administration of a fructose-containing diet, is emphasized in the discussion. However dietary fructose could not be able to display its lipogenic effets in the absence of dietary glucose and that is why sucrose is more efficient than glucose in promoting a net lipid synthesis.     

Eucalyptus leaf extract inhibits intestinal fructose absorption, and suppresses adiposity due to dietary sucrose in rats

Sucrose is more lipogenic than starch, and the extreme ingestion of sucrose induces adiposity and obesity. The aim of this study was to examine the effect of the eucalyptus (Eucalyptus globulus) leaf extract (ELE) on adiposity due to dietary sucrose in rats. In addition, in this study, the effect of ELE on intestinal fructose absorption was also examined. Rats were fed a high-sucrose diet (75 % in calorie base) with or without ELE (10 g/kg diet) for 5 weeks. Body weight was lower in the rats receiving ELE than in the controls (342 (sd 37.9) v. 392 (sd 26.0) g (n 7); P<0.05). Furthermore, ELE resulted in decreases in the triacylglycerol concentrations in the plasma (1.44 (sd 0.448) v. 2.79 (sd 0.677) mmol/l (n 7); P<0.05) and liver (19.1 (sd 5.07) v. 44.1 (sd 16.28) micromol/g (n 7); P<0.05). In contrast, ELE did not show any significant effects in the rats fed a starch diet. When rats were orally given ELE 10 min before fructose administration, the intestinal fructose absorption, which was examined by measuring the elevated concentration of fructose in the portal vein at 30 min after the fructose administration, was significantly inhibited in a dose-dependent manner. Furthermore, in rats fed a high-fructose diet, the plasma and hepatic triacylglycerol concentrations were significantly decreased by ELE. These results indicate that ELE, which inhibits the intestinal fructose absorption, can suppress adiposity in rats that ingest large amounts of sucrose or fructose.