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PubMed1978

Partitioning of Sugar between Growth and Nitrate Reduction in Cotton Roots.

The level of endogenous sugars was inversely related to nitrate availability in young cotton (Gossypium hirsutum L.) plants, with high nitrate causing a greater decline in sugar content of roots than of shoots. High nitrate (low sugar) plants also displayed relatively more shoot growth and less root growth than low nitrate (high sugar) plants. These data are consistent with the theory that roots are poor competitors for sugar, and that sugar supply is a major factor limiting root growth in vivo.The effects of endogenous sugar level on root growth and on nitrate reductase activity in the root were different. When root sugar level was experimentally controlled by varying nitrate concentration in the nutrient solution, root growth was less sensitive than nitrate reductase activity to sugar deficiency. Also, in sterile root tips cultured on media containing a wide range of sucrose concentrations, growth rate was considerably less sensitive to endogenous sugar deficiency than was nitrate assimilation rate. Similarly, in plants which were detopped or girdled, nitrate reductase activity in the roots declined more rapidly than did root sugars, especially glucose and fructose. These results suggest that when sugar is deficient, cotton roots preferentially use it for growth at the expense of nitrate reduction.

Journal Article↗

PubMed1979

Germination of soybean embryonic axes: nucleotide sugar metabolism and initiation of growth.

UDP-Sugars comprise the dominant class of nucleotide sugars in isolated soybean axes during early germination. While "dry" axes contain 1 nanomole per axis of UDP-sugars, further synthesis is initiated upon imbibition such that the concentration of total UDP-sugars reaches 8 nanomoles per axis or roughly 1 millimolar after 10 hours, when the axes begin to elongate. The GDP-sugars are essentially absent before imbibition, accumulate rapidly for 90 min to 173 picomoles per axis, then decrease somewhat, reattaining the earlier peak level shortly before growth begins. Meanwhile, the level of ADP-sugars is unchanged. These data indicate that the 10-hour lag period preceding axis growth does not result from a diminished ability to synthesize a major category of nucleotide sugars.Relative rates of synthesis of individual UDP- and GDP-sugars were determined by incorporation of [(3)H]uridine or [(3)H]guanosine. The distribution of label in the different classes of UDP-sugars and in the single class of GDP-sugar was quantitatively similar when analyzed before, at the onset, or during early growth. It therefore seems unlikely that synthesis of a key nucleotide sugar controls the initiation of growth.The possible relevance of nucleotide sugars to growth is discussed and new methods for enzymic analysis of picomole levels of nucleotide sugars are described.

Journal Article↗

PubMed1992

Sugar Concentrations in Guard Cells of Vicia faba Illuminated with Red or Blue Light : Analysis by High Performance Liquid Chromatography.

Concentrations of soluble sugars in guard cells in detached, sonicated epidermis from Vicia faba leaves were analyzed quantitatively by high performance liquid chromatography to determine the extent to which sugars could contribute to changes in the osmotic potentials of guard cells during stomatal opening. Stomata were illuminated over a period of 4 hours with saturating levels of red or blue light, or a combination of red and blue light. When stomata were irradiated for 3 hours with red light (50 micromoles per square meter per second) in a solution of 5 millimolar KCl and 0.1 millimolar CaCl(2), stomatal apertures increased a net maximum of 6.7 micrometers and the concentration of total soluble sugar was 289 femtomoles per guard cell (70% sucrose, 30% fructose). In an identical solution, 2.5 hours of irradiation with 25 micromoles per square meter per second of blue light caused a maximum net increase of 7.1 micrometers in stomatal aperture and the total soluble sugar concentration was 550 femtomoles per guard cell (91% sucrose, 9% fructose). Illumination with blue light at 25 micromoles per square meter per second in a solution lacking KCl caused a maximum net increase in stomatal aperture of 3.5 micrometers and the sugar concentration was 382 femtomoles per guard cell (82% sucrose, 18% fructose). In dual beam experiments, stomata irradiated with 50 micromoles per square meter per second of red light opened steadily with a concomitant increase in sugar production. Addition of 25 micromoles per square meter per second of blue light caused a further net gain of 3.7 micrometers in stomatal aperture and, after 2 hours, sugar concentrations had increased by an additional 138 femtomoles per guard cell. Experiments with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were performed with epidermis illuminated with 50 micromoles per square meter per second of red light or with 25 micromoles per square meter per second of blue light in solutions containing or lacking KCl. DCMU completely inhibited sugar production under red light, had no effect on guard cell sugar production under blue light when KCl was present, and inhibited sugar production by about 50% when guard cells were illuminated with blue light in solutions lacking KCl. We conclude that soluble sugars can contribute significantly to the osmoregulation of guard cells in detached leaf epidermis of V. faba. These results are consistent with the operation of two different sugar-producing pathways in guard cells: a photosynthetic carbon reduction pathway and a pathway of blue light-induced starch degradation.

Journal Article↗

PubMed2006

Diel timing and frequency of sugar feeding in the mosquito Anopheles gambiae, depending on sex, gonotrophic state and resource availability.

Little is known about the sugar-feeding behaviour of equatorial Africa's principal vector of malaria, Anopheles gambiae Giles (Diptera: Culicidae). It is suspected to feed on plant sugar infrequently, but possibly the timing depends on environmental circumstances, and males may differ markedly from females. These points of uncertainty were clarified in the laboratory, by monitoring both diel and longterm sugar-feeding activity in both sexes. Males fed on sugar in a nocturnal diel rhythm closely approximating non-specific flight activity. Female diel sugar-feeding patterns resembled published rhythms and cycles of host seeking. Males sugar fed nightly at an average frequency of about twice per night, sustained over 17 days. This was substantially higher than the sugar-feeding frequency of females that were allowed both blood and oviposition sites every night: they averaged about one sugar feed in every 4 nights. These females fed on sugar between gonotrophic cycles, after eggs were mature but before the next bloodmeal. They did not sugar feed during the 2 days after blood feeding, while blood was being digested and the eggs developed. A slight delay in the availability of either the oviposition site or blood led to an increase in female sugar-feeding frequency: they averaged more than once per night until the delayed resource was made available. These observations support the conclusion that sugar feeding is a normal part of the biology of both sexes of An. gambiae.

Animals↗

PubMed1983

Insulin regulation of sugar transport in giant muscle fibres of the barnacle.

1. Sugar transport in the giant muscle cells of Balanus nubilus is accelerated during contractile activity and exposure to porcine insulin. The characteristics of hexose-transfer regulation in the giant muscle cells have been examined by studying the transport of 3-O-methylglucose (a non-metabolized sugar) in both intact giant fibres and fibres subjected to internal solute control by internal dialysis.2. Sugar transport in barnacle muscle is mediated by a saturable process which is inhibited by both phloretin and cytochalasin B. Insulin increases the capacity of the transport system with little effect on its apparent affinity for sugar. Under the same conditions insulin increases 3-O-methylglucose-displaceable cytochalasin B binding. The effects of insulin on transport are half-maximal at 5 muM-insulin and are abolished by both insulin antibody and phloretin. The intact barnacle releases an insulin-like material in response to a rise in blood glucose levels.3. Insulin increases the cyclic GMP (cGMP) content and reduces the cyclic AMP (cAMP) content of barnacle muscle. Experiments with fibres injected with aequorin show that insulin also lowers cytosolic ionized Ca levels. The changes in cyclic nucleotide levels induced by insulin precede the effects on sugar transport and cytosolic ionized Ca. During repetitive contractile activity, cAMP, cGMP and ionized Ca levels are raised.4. Agents which raise the cAMP content of barnacle muscle normally inhibit sugar transport. Dibutyryl cAMP also inhibits transport. Alterations in cytosolic ionized Ca levels in intact fibres are without effect on sugar transport. Nevertheless, stimulation of transport by insulin is blunted when cytosolic ionized Ca is lowered by intracellular injection of the Ca-chelating agent, EGTA.5. Sugar uptake in the internally dialysed fibre is inhibited by intracellular application of cAMP. Internal application of Ca and cGMP stimulate sugar uptake in the dialysed fibre. Cyclic AMP reduces the capacity of the transport system whereas Ca and cGMP increase the capacity of the saturable transfer system. Cyclic AMP and cGMP act at kinetically independent sites. Internal ATP (2 mM) inhibits sugar uptake in the dialysed fibre by some 40%, possibly through the production of cAMP.6. External insulin stimulates sugar uptake in the dialysed fibre even when ionized Ca levels are buffered using EGTA. Stimulation by insulin requires the presence of cytosolic ATP and is potentiated by internal application of 1 mM-GTP. In the dialysed fibre stimulation of transport by insulin is greater than that brought about by Ca and cGMP.7. The stimulation of transport by insulin in the intact fibre and its inhibition by dibutyryl cAMP are abolished by intracellular injection of Gpp(NH)p. Injection of intact fibres with GTPgammaS potentiates the stimulation of transport by insulin and renders insulin-activation of transport irreversible. Injection of intact fibres with ATPgammaS leads to the irreversible inhibition of transport.8. Injection of intact fibres with cAMP phosphodiesterase lowers cAMP levels close to zero and stimulates sugar transport. Application of insulin to diesterase-injected fibres still stimulates transport in the absence of altered cytosolic cAMP.

3-O-Methylglucose↗

PubMed1994

Coronary heart disease: prevalence and dietary sugars in Scotland.

STUDY OBJECTIVE: The aim was to investigate the effects of dietary intakes of different types of sugars (extrinsic, intrinsic, and lactose) and the dietary fat to sugar ratio on prevalent coronary heart disease (CHD). DESIGN: This was a baseline cross sectional survey of CHD risk factors. SETTING: Twenty two Scottish health districts were surveyed between 1984 and 1986. PARTICIPANTS: A total of 10,359 men and women aged 40-59 years were screened as part of the Scottish Heart Health Study, and a further 1267 men and women aged 25-39 and 60-64 years were screened as part of the Scottish MONICA (monitoring trends and determinants in cardiovascular disease) Study. The response rates were 74% and 64% respectively. METHODS: Subjects completed a questionnaire which included sociodemographic, health, and food frequency information. Medical history, response to the Rose chest pain questionnaire, and results of a 12 lead ECG recording were used to categorize subjects into CHD diagnosed, previously CHD undiagnosed, or no CHD groups. The chi 2 statistic was used to determine whether the CHD groups differed in their sugar consumption, and multiple logistic regression analysis, with adjustment for other potential coronary risk factors, was used to calculate odds ratios for prevalent CHD by intake fifths of dietary sugars. MAIN RESULTS: Men, but not women, differed in their sugar consumption by CHD group. The odds ratios showed a tendency for a U shaped relationship for extrinsic sugar intake with CHD prevalence, but no significant effect of the fat to sugar ratio (possible marker of obesity) on CHD was seen. CONCLUSIONS: The results suggest that neither extrinsic sugar, intrinsic sugar, nor the fat to sugar ratio are significant independent predictors of prevalent CHD in the Scottish population, when the other major risk factors such as cigarette smoking, blood cholesterol concentration, and antioxidant vitamins intake are accounted for. These new data for different sugar types agree with the consensus view that total sugar intake is not a major marker of coronary heart disease.

Adult↗

PubMed2004

Effect of moisture on impact toughness of sugar-coated tablets manufactured by the dusting method.

The purpose of this study was to clarify the effect of moisture on the impact toughness of sugar-coated tablets manufactured by the dusting method. We demonstrated that moisture plays an important role in the impact toughness of sugar-coated tablets. Moisturizing the sugar-coating layer resulted in enhancement of impact toughness of sugar-coated tablets, while reducing moisture in the sugar-coating layer resulted in weakening of the impact toughness. This was due to the characteristics of sucrose, the main ingredient of the sugar-coating layer, which is a soft and non-fragile material at high moisture levels, but hard and fragile at low moisture levels. We also demonstrated that friability as an indicator of impact toughness changed with time, and friability should be measured at 14 d after manufacture. This is due to moisture movement from outer sugar-coating layer into the inner sugar-coated tablets. Incorporating microcrystalline cellulose (MCC) in the subcoating layer resulted in sugar-coating layers with high resistance against impact even though moisture content of sugar-coated tablets was low. We confirmed the high impact toughness of the sugar-coated tablets with MCC whose moisture content was low from the results of both free fall and friability tests. We suggest that the dusting method using dusting powder containing MCC is a useful method for the production of sugar-coated tablets containing moisture sensitive drugs.

Carbohydrates↗

PubMed2006

Effects of high-sugar ryegrass silage and mixtures with red clover silage on ruminant digestion. 1. In vitro and in vivo studies of nitrogen utilization.

Two experiments were carried out to determine the effects of feeding grass silages differing in their water-soluble carbohydrate content, with or without red clover silage, on the efficiency of nutrient use. High-sugar grass, control grass, and red clover were ensiled in laboratory silos for use in an in vitro experiment (Exp. 1). For an in vivo experiment (Exp. 2), the same forage types were baled and ensiled. All silages were well preserved; within experiments the grass silages had similar composition, except for greater (P < 0.05) water-soluble carbohydrate concentrations in the high-sugar than the control grass silage. In Exp. 1, high-sugar grass, control grass, and red clover silages were fed alone or as mixtures (30:70, 50:50, or 70:30 on a DM basis, respectively) of each grass with the red clover silage to a simulated rumen culture system. There were no significant differences in microbial N flow or efficiency of microbial protein synthesis between individual forages. However, the corresponding values for the 70:30 ratio of high-sugar grass:red clover silage were greater (P < 0.05) than for the red clover silage. The value for the efficiency of N use (g of microbial N/g of feed N) was greater (0.86; P < 0.05) for high-sugar grass silage than the control grass silage. In addition, the high-sugar grass:red clover silage mixtures all gave greater (P < 0.05) values for the efficiency of N use than red clover silage alone; this difference was not achieved with the control grass mixture. Experiment 2 was an incomplete Latin square design conducted with 6 Here-ford x Friesian steers (163 +/- 5.9 kg of BW) with rumen and duodenal cannulas fed the following 5 silage diets: high-sugar grass silage; control grass silage; high-sugar grass and red clover silage (50:50 DM basis); control grass and red clover silage (50:50 DM basis); and red clover silage. Rumen NH3-N concentration was lowest (P < 0.05) with the high-sugar grass silage. Microbial N flows to the duodenum and efficiency of microbial protein synthesis were greater (P < 0.05) for steers fed the high-sugar grass silage than for control grass and red clover silages, and mixing red clover with grass silages increased (P < 0.05) these values compared with red clover silage alone. In both experiments, the efficiency of incorporation of silage N into microbial N was more than 20% greater (P < 0.05) for high-sugar grass than for control grass silage. These data suggest that grass silage with high-sugar content provides a forage-based strategy for balancing N and energy supply and improving the efficiency of use of grass silage N in the rumen.

Ammonia↗

PubMed2001

The use of sugar fortified with iron tris-glycinate chelate in the prevention of iron deficiency anemia in preschool children.

In the present work, the effectiveness of consumption for 6 months of iron fortified sugar in the prevention or control of iron deficiency anemia was evaluated in 93 children (10-48 months old) attending a day care center in São Paulo, Brazil. Each child consumed 20 g of fortified sugar per day for 5 days a week in orange juice during breakfast. Two levels of fortification were tested using iron tris-glycinate chelate as the source of iron. Level one sugar contained 10 mg of iron/kg of sugar, and level 2, 100 mg of iron/kg. The children were assigned to either of the two groups. The first group (n = 42) received level 1 sugar, and those of group two (n = 52) received level 2 sugar. The daily iron intake corresponded to 2 and 20% of the RDA. At the end of the 6 months trial period, significant increases in weight/height ratio was observed in both groups. In the group consuming level 1 fortified sugar the mean change in hemoglobin concentration was 0.4 g/dL (from 11.3 grams to 11.7 g/dL), and in the group consuming level two fortified sugar the mean hemoglobin increase was also 0.4 g/dL (from 11.6 to 12.0 g/dL). Both changes were highly significant (p < 0.001). When only the anemic children were considered (32/93), the increment of hemoglobin was 1.4 g/dL. In anemic children there was a significant increase in the levels of serum ferritin. The increase was more notorious in group 2 children. We verified that the acceptability of the iron-fortified sugar was excellent. There were no detectable changes in the organoleptic characteristics of the fortified sugar as compared with unfortified sugar. No differences in response were observed between the two groups indicating that probably the lower level of iron was absorbed more efficiently that the higher level. The iron tris-glycinate chelate was very well tolerated with no side effects registered. It was concluded that even with low iron levels, the consumption of iron fortified sugar is an effective, low cost intervention for the control and prevention of iron deficiency anemia in preschool children.

Anemia, Iron-Deficiency↗

PubMed1992

Nutrient intakes and body weights of persons consuming high and moderate levels of added sugars.

We classified a nationally representative sample of persons aged 4 years and older as high or moderate consumers of added sugars (ie, sugars added to foods by processors or consumers). Intake of added sugars was determined on the basis of grams consumed per kilogram of body weight (g/kg) and on the basis of percent of dietary energy from added sugars (% kcal). Regardless of the intake measure used, high consumers of added sugars had a significantly lower percentage of dietary energy from fat than did moderate consumers of added sugars. Persons defined by the % kcal measure as high consumers of added sugars took in lower percentages of the Recommended Dietary Allowances (RDAs) for 11 vitamins and minerals; these high consumers had body weights similar to those of their moderate counterparts. Persons defined as high consumers by the g/kg measure consumed greater percentages of the RDAs than did their moderate counterparts; these high consumers more frequently selected foods from categories likely to contain sugar-rich foods but weighed significantly less than did moderate consumers. Thus, different approaches to defining intake of added sugars revealed two patterns of high consumption of added sugars with different levels of nutritional risk. Conditions of overweight were not associated with high intake of added sugars. Educational efforts, therefore, should focus on those consumers who tend to substitute foods rich in added sugars for more nutritionally desirable foods.

Adolescent↗

PubMed1995

Antioxidant vitamin adequacy in relation to consumption of sugars.

OBJECTIVE: To investigate the prevalence of antioxidant vitamin inadequacy and low fibre intakes according to total, intrinsic, extrinsic and milk-sugar consumption groups. DESIGN: Age- and sex-stratified cross-sectional study of coronary risk factors and diet. Based on a personal health and food frequency questionnaire with a clinic attendance for body measurements. SETTING: Ten general practitioners' surgeries from each of 22 Scottish districts (12 Mainland Health Boards) surveyed during 1984-1986. SUBJECTS: 11,626 men and women aged 25-64 years who participated in the baseline Scottish Heart Health (SHHS) and MONICA studies. Overall response rate was 69% after one reminder letter. MAIN OUTCOME MEASURES: Both the mean daily intakes of fibre and vitamins A (retinol and carotenes), C and E, and the percentage of each sex group who fall below the dietary reference values for each nutrient are reported according to fifths of dietary sugars. The percentage of the population variation in vitamin and fibre intake which can be explained by consumption of the different sugars is provided from multiple analysis of variance techniques. RESULTS: Intrinsic sugar intake is positively related to antioxidant vitamin and fibre intake (correlation coefficients, r, between 0.1 and 0.61 apart from retinol, r = -0.06), due to their mutual occurrence in fresh fruits and vegetables, while consumption of milk sugars tends to be weekly inversely related to antioxidant vitamin and fibre intake (apart from vitamin C, r = 0.02-0.06). Both low and high extrinsic sugar intake seems to be associated with poorer antioxidant vitamin and fibre-containing diets compared with a consumption of extrinsic sugar of between 6.5 and 15.6% energy for men and 4.8 and 11.6% energy for women. Intake of different sugar types is related to the antioxidant nutrient adequacy of a diet independent of age, smoking habit, total energy intake, alcohol consumption, weight and height. Fibre intake is below the recommended value at all levels of dietary sugars. CONCLUSIONS: Prevalence of antioxidant vitamin adequacy is significantly related to dietary sugar intake. However, relatively low extrinsic sugar consumption appears equally associated with a poor quality diet as does a relatively high intake. It may be concluded that the dietary reference values for sugars err on the cautions side, with respect to their effect on antioxidant nutrient adequacy.

Adult↗

PubMed1976

[Sugar substitutes in the diabetic diet].

The decreased glucsoe utilization in diabetes mellitus justifies the use of sugar substitutes ("diabetic sugar") if two conditions are fulfilled: 1)The sugar substitute should be a carbohydrate which does not lead, or only to a slight degree, to hyperglycaemia and thus, in this respect, differs distinctly from sugars such as glucose and saccharose. 2) The sugar substitute must not cause undesired side-effects. The absorption, utilization and side-effects of the sugar substitutes fructose, sorbitol and xylitol were investigated. They were found to be more slowly absorbed than glucose and thus to offer the advantage of better utilization under conditions of limited insulin production. However, the particularly slow passive absorption of sorbitol and xylitol can sometimes be a disadvantage, since osmotic diarrhoea may occur after administration of high oral doses. The sugar substitutes enter the metabolism enzymatically and are utilized mainly in the liver. The peripheral state was investigated after intravenous, intraduodenal and oral administration of glucose and fructose to healthy subjects. Liver metabolism was examined (Dietze) by comparing hepatic venous and arterial concentrations after intravenous administration of the sugars. Also, diabetic patients received glucose and fructose orally. As previously demonstrated, the investigations using several techniques showed a smaller influence on blood glucose and serum insulin concentrations after administration of fructose, sorbitol and xylitol than after glucose. If no metabolic changes occur after intravenous administration of high doses, no such changes need be expected after oral administration of small doses. Nor did measurements in hepatic venous blood (Dietze) show any marked effect of fructose on the blood glucose level. The healthy subjects showed no significant changes in blood glucose or serum insulin concentration after either intraduodenal or oral administration of fructose, whereas they showed a considerable increase after glucose administration. Investigations in adult-type diabetics revealed a better utilization of fructose than glucose. With correct dosage, sugar substitutes are able to increase the carbohydrate tolerance and, under certain conditions, to achieve a relative stabilization of the metabolism of unstable diabetics. The antiketogenic activity of sugar substitutes is particularly pronounced. Side-effects such as high blood levels of urea, lactate, triglycerides and bilirubin or a decrease in hepatic adenin nucleotides do not occur after oral administration, nor are they of importance after intravenous administration with correct dosage. The osmotic diarrhoea occurring after intake of sorbitol or xylitol is caused by their slow absorption and limits the consumption of these sugar substitutes. In the often obese adult-type diabetics, the calorie intake inherent in the consumption of diabetic sugars may have an unfavourable influence on their weight...

Adult↗

PubMed2002

Sugar exudation by roots of kallar grass [Leptochloa fusca (L.) Kunth] is strongly affected by the nitrogen source.

Exudation of sugars (glucose, fructose and sucrose) and that of cations and anions from intact roots of kallar grass [Leptochloa fusca (L.) Kunth] grown hydroponically with ammonium or nitrate (3 mM) as N source was investigated. In different experiments, plants grown on ammonium had slightly higher sugar contents than nitrate-grown plants, but their total sugar exudation during a 2-h period was up to 79-fold higher than under nitrate nutrition. Relative root exudation of inorganic anions and cations and that of amino acids (as a percentage of the internal contents exuded per time) was either similar or slightly higher from ammonium-grown than from nitrate-grown plants. Analysis of root architectural parameters revealed that ammonium-grown plants had a higher number of root tips/side roots per gram root fresh weight than nitrate-grown plants, whereas other root parameters, viz. length, diameter, volume and surface area were similar under the two N sources. A majority of the fine roots having diameter up to 0.4 mm represented up to 86% of the total root length, 64% of the total root surface area, and 35% of the total root volume; the root length and surface area per root system of that major root population were similar in ammonium- and nitrate-grown plants. Apparently, root architecture was not responsible for the different exudation rates. Within 12-24 h after shifting ammonium-grown plants to nitrate nutrition, root sugar levels and visible root architecture remained unchanged, yet the sugar exudation rate was reduced 30-fold. Short-term uptake of [14C]glucose (10 microM) from the rooting medium was similar for ammonium- and nitrate-grown plants. Thus, the very different sugar exudation rates were neither related to internal root sugar concentration, nor to the different root architecture, nor to differential resorption of sugars by ammonium- versus nitrate-grown plants. Increased external Ca2+ did not alter sugar exudation, and decreased external pH (4.5) only slightly increased sugar exudation from roots of nitrate-grown plants kept at pH 6.5. It is suggested that the much higher sugar exudation in response to ammonium may facilitate the ecologically and economically important association of diazotrophs with kallar grass roots.

Amino Acids↗

PubMed1990

Hyperphagia in rats produced by a mixture of fat and sugar.

The hyperphagic and weight-promoting effects of feeding rats a sugar-fat mixture were compared to those of presenting only one of the two nutrients. Experimental groups were fed sugar (sucrose), fat (corn oil), or a sugar-fat mixture as an option to chow; options were in the form of water solutions or emulsions. The control group was fed only chow. The sugar-fat group displayed a robust hyperphagia (greater than 36%), relative to the control group; the hyperphagic response was greater than that observed in the fat group but not in the sugar group. The sugar-fat group selected more calories from the option than the other two experimental groups. Body weight gains were also greater in the sugar-fat group than in the fat and sugar groups. Addition of saccharin to the fat emulsion increased fat and total intakes to levels close to those of the sugar-fat mixture. In a second experiment, the relative palatability of the plain and sweet fat emulsions was assessed with two-bottle preference tests. The sugar-fat mixture was preferred to the saccharin-fat mixture, which in turn was preferred to the plain-fat emulsion. These results suggest that the sweetness of the sugar-fat mixture contributed to the pronounced hyperphagia and obesity obtained with this diet option.

Animals↗

PubMed2004

Evolutionary legacy: form of ingestion, not quantity, is the key factor in producing the effects of sugar on human health.

Tens of dietary trials have been conducted to investigate the metabolic effects of sugar (sucrose) and its impact on human health. All of those studies took into account only the quantity of ingested sugar. By contrast, not a single study attempted to assess whether the form in which sugar is consumed plays a role in producing its metabolic effects. The failure of cohorts of researchers to specify how they administered sugar in their dietary trials may well explain why the results of those studies are extremely contradictory. These discrepant findings, understandably, resulted in conflicting opinions about sugar and in divergent guidelines about its recommended consumption. The evolutionary line of reasoning expounded in this article leads to conclude that the form in which sugar is ingested, not its quantity, constitutes the most important factor in producing the metabolic effects of sugar and its impact on human health. As a consequence, for example, the consumption of 100 g of sugar per day can be either detrimental or innocuous, depending on the form in which sugar is ingested. Specifically, the evolutionary hypothesis advanced in this paper implies that sugar can predispose to type 2 diabetes and can cause unhealthy changes in blood lipids if it is consumed in solid forms or in dense solutions containing more than 250 g/L, whereas sugar is harmless if it is consumed in more dilute concentrations. This evolutionary hypothesis, in view of its intuitively far-reaching clinical implications, should be tested by at least one dietary trial.

Administration, Oral↗

PubMed2001

A comparison of nectar- and honeydew sugars with respect to their utilization by the hymenopteran parasitoid Cotesia glomerata.

Fourteen naturally occurring sugars were individually tested with respect to their effect on Cotesia glomerata longevity. Parasitoids kept with solutions of either sucrose, glucose and fructose lived for >30 days. This constitutes a factor 15 increase in life span in comparison to control individuals kept with water only. Stachyose, mannose, melezitose, melibiose, maltose and erlose increased parasitoid longevity by a factor of 11.2-6.9. Solutions of galactose and trehalose had a marginal, but still significant effect. Lactose and raffinose did not raise parasitoid longevity, while rhamnose actually reduced parasitoid survival. In an additional experiment, the relationship between quantity of sugar consumption and longevity was established for all 14 sugars. To study the effect of an unsuitable sugar in sugar mixtures, a range of glucose:rhamnose mixtures was tested. Even at 20% of the sugar mixture rhamnose suppressed the nutritional benefit of the 80% glucose. The nutritional suitability of the sugars shows a positive correlation with the previously reported gustatory response towards the individual sugars. Patterns of sugar utilization are discussed with respect to hydrolytic enzymes and carbohydrate biochemical characteristics. Our findings for C. glomerata are compared to patterns of sugar utilization reported for other species. The comparison between C. glomerata and its host Pieris brassicae reveals that the parasitoid is capable of utilizing a range of sugars that are unsuitable to its herbivorous host. This specificity opens up opportunities to select food supplements for biological control programs that selectively target the antagonist, without concurrently enhancing herbivore fitness.

Journal Article↗

PubMed2000

The relationships between dietary guidelines, sugar intake and caries in primary teeth in low income Brazilian 3-year-olds: a longitudinal study.

OBJECTIVES: To investigate the effects of dietary guidelines on sugar and sugar intake at day nurseries, and other potential risk factors on dental caries in two groups of low socio-economic nursery schoolchildren. DESIGN: Nursery based, longitudinal study. SETTING: Metropolitan area of Recife, north-eastern Brazil. SAMPLE AND METHODS: The study population comprised 510, 3-year-old low socio-economic nursery schoolchildren. Sugar intake at the nursery was based upon a weighed inventory method during 2 non-consecutive days. Parents answered a questionnaire. RESULTS: Children attending nurseries not adopting guidelines on reduction of sugar intake had a higher caries risk, with an odds ratio of 3.6 compared to those attending nurseries with guidelines. A higher caries increment was related to higher daily frequency and weight of sugar intake at nursery, overall daily frequency of sugar intake (sugar intake at home plus nursery), past caries experience, use of fluoride, and habits related to toothbrushing. Children having more than 32.6 g of sugar daily at nursery were 2.99 times more likely to have high caries increment than those having less than that amount. CONCLUSIONS: Sugar intake at nursery and the adoption of guidelines on sugar were associated with lower caries increment in low income nursery schoolchildren. A number of modifiable factors such as a higher daily frequency and weight of sugar intake at nursery, use of fluoride and habits related to toothbrushing were strongly related to caries increment.

Brazil↗

PubMed2000

Sugars in the gut of the sandfly Phlebotomus orientalis from Dinder National Park, Eastern Sudan.

The sandfly Phlebotomus orientalis Parrot (Diptera: Psychodidae) is the vector of visceral leishmaniasis in eastern and Upper Nile regions of Sudan, where vector infection rates of over 7% have been reported. Sugars are known to be important for development of the parasite and for increasing the survival and oviposition rates of several species of sandflies. In the present study we have analysed the sugars present in the guts of individuals and groups of male and female P. orientalis and compared these with sugars from several potential local plant sources: Acacia seyal, Balanites aegyptiaca and Combretum kordofanum. The distribution of these trees in Sudan is closely correlated with that of P. orientalis. Only 20% of individually analysed female sandflies had significant amounts of sugars present suggesting that P. orientalis either digest their sugar meal quickly or do not require regular sugar meals. Interestingly, the sugars present in the males were significantly different to those found in the females, indicating that they had fed on different sugar sources. There was evidence that fruit sugars from Balanites aegyptiaca, Combretum kordofanum and aphid or coccid honeydew are utilized by male and female P. orientalis. There was evidence to indicate that female P. orientalis feeds directly on honeydew. There was no evidence to indicate that direct feeding on leaves is a typical source for the sugar meal. There was no melizitose and only a very small amount of turanose present in the male, suggesting that honeydew was not an important sugar source for males.

Animals↗