Efectos metabólicos del consumo excesivo de fructosa añadida / Metabolic effects of excessive fructose consumption added

El consumo de fructosa ha aumentado en los últimos 50 años por la incorporación a la dieta de jarabe de maíz alto en fructosa (JMAF), presente en productos industrializados, como las bebidas azucaradas. Se puede asociar la ingesta de fructosa en altas concentraciones con el aumento de la obesidad y trastornos metabólicos. La fructosa, un azúcar natural que se encuentra en muchas frutas, se consume en cantidades significativas en las dietas occidentales. En cantidades iguales, es más dulce que la glucosa o la sacarosa y, por lo tanto, se usa comúnmente como edulcorante. Debido al incremento de obesidad entre la población joven y general y a los efectos negativos que puede tener a corto y largo plazo es importante considerar de donde provienen las calorías que se ingieren diariamente. Esta revisión describirá la relación entre el consumo de fructosa en altas concentraciones y el riesgo de desarrollar obesidad, resistencia a la insulina, lipogenesis de novo e inflamación.

The consumption of fructose has increased in the last 50 years due to the incorporation into the diet of high fructose corn syrup (HFCS), present in industrialized products, such as sugary drinks. The intake of fructose in high concentrations can be associated with the increase of obesity and metabolic disorders. Fructose, a natural sugar found in many fruits, is consumed in significant quantities in Western diets. In equal amounts, it is sweeter than glucose or sucrose and, therefore, is commonly used as a sweetener. Due to the increase of obesity among the young and general population and the negative effects that can have in the short and long term it is important to consider where the calories that are ingested daily come from. This review will describe the relationship between fructose consumption in high concentrations and the risk of developing obesity, insulin resistance, de novo lipogenesis, nonalcoholic fatty liver, inflammation and metabolic syndrome.

Postprandial metabolic effects of fructose and glucose in type 1 diabetes patients: a pilot randomized crossover clinical trial

ABSTRACT Objective To test the influence of oral fructose and glucose dose-response solutions in blood glucose (BG), glucagon, triglycerides, uricaemia, and malondialdehyde in postprandial states in type 1 diabetes mellitus (T1DM) patients. Subjects and methods The study had a simple-blind, randomized, two-way crossover design in which T1DM patients were selected to receive fructose and glucose solutions (75g of sugars dissolved in 200 mL of mineral-water) in two separate study days, with 2-7 weeks washout period. In each day, blood samples were drawn after 8h fasting and at 180 min postprandial to obtain glucose, glucagon, triglycerides, uric acid, lactate, and malondialdehyde levels. Results Sixteen T1DM patients (seven men) were evaluated, with a mean age of 25.19 ± 8.8 years, a mean duration of disease of 14.88 ± 4.73 years, and glycated hemoglobin of 8.13 ± 1.84%. Fructose resulted in lower postprandial BG levels than glucose (4.4 ± 5.5 mmol/L; and 12.9 ± 4.1 mmol/L, respectively; p < 0.01). Uric acid levels increased after fructose (26.1 ± 49.9 µmol/L; p < 0.01) and reduced after glucose (-13.6 ± 9.5 µmol/L; p < 0.01). The malondialdehyde increased after fructose (1.4 ± 1.6 µmol/L; p < 0.01) and did not change after glucose solution (-0.2 ± 1.6 µmol/L; p = 0.40). Other variables did not change. Conclusions Fructose and glucose had similar sweetness, flavor and aftertaste characteristics and did not change triglycerides, lactate or glucagon levels. Although fructose resulted in lower postprandial BG than glucose, it increased uric acid and malondialdehyde levels in T1DM patients. Therefore it should be used with caution. ClinicalTrials.gov registration: NCT01713023.

Growth kinetic models of five species of Lactobacilli and lactose consumption in batch submerged culture

Abstract Kinetic behaviors of five Lactobacillus strains were investigated with Contois and Exponential models. Awareness of kinetic behavior of microorganisms is essential for their industrial process design and scale up. The consistency of experimental data was evaluated using Excel software. L. bulgaricus was introduced as the most efficient strain with the highest biomass and lactic acid yield of 0.119 and 0.602 g g-1 consumed lactose, respectively. The biomass and carbohydrate yield of L. fermentum and L. lactis were slightly less and close to L. bulgaricus. Biomass and lactic acid production yield of 0.117 and 0.358 for L. fermentum and 0.114 and 0.437 g g-1 for L.actobacillus lactis were obtained. L. casei and L. delbrueckii had the less biomass yield, nearly 11.8 and 22.7% less than L. bulgaricus, respectively. L. bulgaricus (R 2 = 0.9500 and 0.9156) and L. casei (R 2 = 0.9552 and 0.8401) showed acceptable consistency with both models. The investigation revealed that the above mentioned models are not suitable to describe the kinetic behavior of L. fermentum (R 2 = 0.9367 and 0.6991), L. delbrueckii (R 2 = 0.9493 and 0.7724) and L. lactis (R 2 = 0.8730 and 0.6451). Contois rate equation is a suitable model to describe the kinetic of Lactobacilli. Specific cell growth rate for L. bulgaricus, L. casei, L. fermentum, L. delbrueckii and L. lactis with Contois model in order 3.2, 3.9, 67.6, 10.4 and 9.8-fold of Exponential model.

Fructose and NAFLD: metabolic implications and models of induction in rats / Frutose e NAFLD: implicações metabólicas e modelos de indução em ratos

PURPOSE: The increase in fructose consumption is paralleled by a higher incidence of obesity worldwide. This monosaccharide is linked to metabolic syndrome, being associated with hypertriglyceridemia, hypertension, insulin resistance and diabetes mellitus. It is metabolized principally in the liver, where it can be converted into fatty acids, which are stored in the form of triglycerides leading to NAFLD. Several models of NAFLD use diets high in simple carbohydrates. Thus, this study aimed to describe the major metabolic changes caused by excessive consumption of fructose in humans and animals and to present liver abnormalities resulting from high intakes of fructose in different periods of consumption and experimental designs in Wistar rats. METHODS: Two groups of rats were fasted for 48 hours and reefed for 24 or 48 hours with a diet containing 63 percent fructose. Another group of rats was fed an diet with 63 percent fructose for 90 days. RESULTS: Refeeding for 24 hours caused accumulation of large amounts of fat, compromising 100 percent of the hepatocytes. The amount of liver fat in animals refed for 48 hours decreased, remaining mostly in zone 2 (medium-zonal). In liver plates of Wistar rats fed 63 percent fructose for 45, 60 and 90 days it's possible to see that there is an increase in hepatocytes with fat accumulation according to the increased time; hepatic steatosis, however, is mild, compromising about 20 percent of the hepatocytes. CONCLUSIONS: Fructose is highly lipogenic, however the induction of chronic models in NAFLD requires long periods of treatment. The acute supply for 24 or 48 hours, fasted rats can cause big changes, liver steatosis with macrovesicular in all lobular zones.

OBJETIVO: O aumento do consumo de frutose é concomitante a maior incidência mundial de obesidade. Este monossacarídeo está relacionado à Síndrome Metabólica, sendo vinculado à hipertrigliceridemia, hipertensão arterial, resistência à insulina e diabetes mellitus. É metabolizada principalmente no fígado, onde pode ser convertida em ácidos graxos, os quais serão estocados na forma de trigligérides ocasionando a esteatose hepática não alcoólica (NAFLD). Vários modelos de NAFLD utilizam dietas ricas em carboidratos simples. Desta forma, este trabalho teve como objetivos descrever as principais alterações metabólicas causadas pelo consumo excessivo de frutose em humanos e em animais e apresentar as alterações hepáticas decorrentes da alta ingestão de frutose em diferentes períodos de consumo e desenhos experimentais em ratos Wistar. MÉTODOS: Dois grupos de ratos Wistar foram mantidos em jejum durante 48 horas e realimentados por 24 ou 48 horas com dieta contendo 63 por cento de frutose. Outro grupo de ratos Wistar foi alimentado com 63 por cento de frutose durante 90 dias. RESULTADOS: A realimentação por 24 horas provocou acúmulo de grande quantidade de gordura. A quantidade de gordura hepática nos animais realimentados por 48 horas diminuiu, mantendo-se principalmente nas zona 2 (medio-zonal). Em fígados de ratos Wistar alimentados com 63 por cento de frutose até 90 dias foi possível observar que há aumento de hepatócitos com acúmulo de gordura consequente ao aumento do tempo, no entanto a esteatose hepática é leve (20 por cento). CONCLUSÕES: A frutose é altamente lipogênica, no entanto a indução de NAFLD em modelos crônicos necessita de longos períodos de tratamento. A oferta aguda, por 24 ou 48 horas, a ratos mantidos em jejum é capaz de ocasionar grandes mudanças hepáticas, com presença de esteatose macrovesicular em todas as zonas lobulares.

S. mutans biofilm model to evaluate antimicrobial substances and enamel demineralization

The aim of this study was to validate a model of S. mutans biofilm formation, which simulated 'feast-famine' episodes of exposure to sucrose that occur in the oral cavity, showed dose-response susceptibility to antimicrobials and allowed the evaluation of substances with anticaries potential. S. mutans UA159 biofilms were grown for 5 days on bovine enamel slabs at 37°C, 10 percent CO2. To validate the model, the biofilms were treated 2x/day with chlorhexidine digluconate (CHX) at 0.012, 0.024 and 0.12 percent (concentration with recognized anti-plaque effect) and 0.05 percent NaF (concentration with recognized anti-caries effect). CHX showed dose-response effect decreasing biomass, bacterial viability and enamel demineralization (p < 0.05). Whereas, 0.05 percent NaF did not show antimicrobial effect but had similar effect to that of 0.12 percent CHX decreasing enamel demineralization (p < 0.05). The model developed has potential to evaluate the effect of substances on biofilm growth and on enamel demineralization.

Fructose and cardiometabolic disorders: the controversy will, and must, continue: [review]

The present review updates the current knowledge on the question of whether high fructose consumption is harmful or not and details new findings which further pushes this old debate. Due to large differences in its metabolic handling when compared to glucose, fructose was indeed suggested to be beneficial for the diet of diabetic patients. However its growing industrial use as a sweetener, especially in soft drinks, has focused attention on its potential harmfulness, possibly leading to dyslipidemia, obesity, insulin resistance/metabolic syndrome and even diabetes. Many new data have been generated over the last years, confirming the lipogenic effect of fructose as well as risks of vascular dysfunction and hypertension. Fructose exerts various direct effects in the liver, affecting both hepatocytes and Kupffer cells and resulting in non-alcoholic steatotic hepatitis, a well known precursor of the metabolic syndrome. Hepatic metabolic abnormalities underlie indirect peripheral metabolic and vascular disturbances, for which uric acid is possibly the culprit. Nevertheless major caveats exist (species, gender, source of fructose, study protocols) which are detailed in this review and presently prevent any firm conclusion. New studies taking into account these confounding factors should be undertaken in order to ascertain whether or not high fructose diet is harmful.

Características da dieta nas diferentes fases da evolução do diabetes melito tipo 1 / Diet composition along the evolution of type 1 diabetes mellitus

A importância da terapia nutricional no tratamento do diabetes melito tem sido enfatizada desde os primórdios de seu conhecimento, quando era a única intervenção efetiva. No diabetes tipo 1, a dieta adequada é fundamental em conseqüência de sua conjugação com a utilização da insulina exógena. A ingestão energética adequada, para obtenção de peso normal mantém o anabolismo, assegurando crescimento e desenvolvimento, assim como diminui a resistência à insulina. O uso correto dos micro e macronutrientes é de fundamental importância. O conhecimento do metabolismo dos carboidratos e sua relação com a elevação glicêmica, em seus aspectos qualitativos e quantitativos é enfatizada por possibilitar um bom controle, principalmente no período pós-prandial. É comentada também a correta utilização de proteínas para prevenir ou tratar nefropatia e gorduras para evitar a dislipidemia, obesidade e doença cardiovascular. Sacarose e edulcorantes artificiais devem ser utilizados com critérios. A aderência ao tratamento, entretanto, é fundamental para obtenção das metas desejadas.

The importance of nutrition therapy in treating diabetes mellitus has been emphasized since it was first identified, being the only effective intervention then. In Type 1 diabetes, its importance is even more pronounced due to its association with the use of exogenous insulin. Appropriate caloric ingestion in order to attain normal body weight maintains anabolism, warranting growth and development and decreases insulin resistance. The correct use of micronutrients and macronutrients is vitally important. The knowledge of carbohydrate metabolism and its association with glycemic elevation, in qualitative and quantitative aspects, is emphasized since it enables good control, especially during the postprandial period. The correct use of proteins to prevent or treat nephropathies and lipids or to avoid dyslipidemia, obesity, and cardiovascular disease are also addressed. Sucrose and artificial sweeteners should be used with care. Compliance with treatment, however, is the key to reach the desired goals.

Lack of mutagenicity of stevioside and steviol in Salmonella typhimurium TA 98 and TA 100.

Stevioside, a sweet-tasting diterpene glycoside derived from Stevia rebaudiana, and steviol, a product from enzymatic hydrolysis of stevioside, were tested for mutagenic activity by the in vitro Ames test, a preincubation method, using Salmonella typhimurium TA 98 and TA 100 as the tester strains, either in the presence or absence of metabolic activating system derived from the sodium phenobarbital and 5,6-benzoflavone pretreated liver S9 fractions from various animal species including rat, mouse, hamster and guinea pig. Stevioside and steviol at the concentrations up to 50 mg and 2 mg per plate, respectively showed no mutagenic effect on both tester strains either in the presence or absence of metabolic activating system. However, at the high concentration both stevioside and steviol showed some toxic effects on both tester strains. The toxic effect was decreased in the presence of the metabolic activating system.

O açúcar e os substitutos alternativos do açúcar / Sugar and its alternative substitutes

Açúcar e os substitutos alternativos do açúcar é uma matéria complexa dentro dos procedimentos médicos dietéticos. A intençäo da sociedade moderna consumidora, obesidade e doenças coronarianas, säo atributos para investigaçöes médicas. Analisa-se o metabolismo e os chamados açúcares alternativos e os efeitos na saúde humana, do ponto de vista epidemiológico e farmacológico