Consuming fructose-sweetened beverages increases body adiposity in mice

Research on the effects of L-carnitine and trans-chalcone on endoplasmic reticulum stress and oxidative stress in high-fructose corn syrup-fed rats

Purpose

The debate on the metabolic effects of high fructose corn syrup (HFCS) continues. The deterioration of endoplasmic reticulum (ER) homeostasis is called ER stress. Glucose-regulated protein-78 (GRP-78) and X-box binding protein-1 (XBP-1) are key markers of ER stress and the therapeutic targets of diseases. Sterol regulatory element binding protein-1c (SREBP-1c) is the most important transcription factor that regulates the expression of enzymes for fatty acid synthesis. The purpose of this paper is to research the effects of L-carnitine and trans-chalcone on ER stress and oxidative stress parameters, and to explore the therapeutic potential of L-carnitine and trans-chalcone molecules.

Design/methodology/approach

Forty male wistar albino rats randomly selected were divided into five groups. All groups are fed with standard chow (ad libitum). While Group I was fed with drinking water, Group II, III, IV and V were fed with water containing 15% HFCS. L-carnitine was given to Group IV and trans-chalcone to Group V, and both were dissolved with DMSO and given intraperitoneally. Group III was not given anything additional.

Findings

While the amount of water consumption of HFCS-fed rats has increased, the amount of feed consumption has decreased. The weights of rats in Group II and Group III have increased significantly compared to Group I (p = 0.001, p = 0.001 respectively). In Group III, GRP78, XBP-1; malondialdehyde level (p < 0.001, p = 0.001, p = 0.041); total cholesterol, triglyceride, LDL levels (p = 0.001, p < 0.001, p = 0.009, p = 0.001, respectively) have increased significantly.

Originality/value

To the best of the authors’ knowledge, this study is the first report to show that excessive HFCS consumption causes oxidative stress and ER stress. The antioxidant and antiobesity properties of trans chalcone have been demonstrated. Extensive experimental and clinical studies should be conducted.

Impact of dietary propionate on fructose-induced changes in lipid metabolism, gut microbiota and short-chain fatty acids in mice

Propionate has antimicrobial activity and is suggested to influence lipid metabolism. Here, we investigated the effect of propionate on lipid metabolism and the gut microbiome in fructose-fed mice as a model of diet-induced steatosis and gut dysbiosis. Therefore, 48 male wild-type mice were fed isoenergetic diets with either 0% fructose (F-) or 40% fructose (F+) that contained 0% propionate (P-) or 1% propionate (P+) for 7 weeks. Mice that received the F+ diets developed fatty livers, had fewer small intestinal proteobacteria and colonic actinobacteria and were characterised by changes in bacterial genera (e.g., Allobaculum, Lachnospiraceae, and Escherichia). Interestingly, mice fed the F+ diets had higher levels of propionate and butyrate in the circulation than mice fed the F- diets (p < 0.05). Treatment with propionate influenced neither hepatic or plasma lipids nor levels of circulating SCFAs. With the exception of Verrucomicrobia, other bacterial phyla were not affected by propionate.

Expression of placental glucose transporter proteins in pregnancies complicated by fetal growth disorders

During pregnancy fetal growth disorders, including fetal macrosomia and fetal growth restriction (FGR) are associated with numerous maternal-fetal complications, as well as due to the adverse effect of the intrauterine environment lead to an increased morbidity in adult life. Accumulating evidence suggests that occurrence of fetal macrosomia or FGR, may be associated with alterations in the transfer of nutrients across the placenta, in particular of glucose. The placental expression and activity of specific GLUT transporters are the main regulatory factors in the process of maternal-fetal glucose exchange. This review article summarizes the results of previous studies on the expression of GLUT transporters in the placenta, concentrating on human pregnancies complicated by intrauterine fetal growth disorders. Characteristics of each transporter protein found in the placenta is presented, alterations in the location and expression of GLUT isoforms observed in individual placental compartments are described, and the factors regulating the expression of selected GLUT proteins are examined. Based on the above data, the potential function of each GLUT isoform in the maternal-fetal glucose transfer is determined. Further on, a detailed analysis of changes in the expression of glucose transporters in pregnancies complicated by fetal growth disorders is given, and significance of these modifications for the pathogenesis of fetal macrosomia and FGR is discussed. In the final part novel interventional approaches that might reduce the risk associated with abnormalities of intrauterine fetal growth through modifications of placental GLUT-mediated glucose transfer are explored.

Differentiated Hepatic Response to Fructose Intake during Adolescence Reveals the Increased Susceptibility to Non-Alcoholic Fatty Liver Disease of Maternal High-Fat Diet Male Rat Offspring

SCOPE

Non-alcoholic fatty liver disease (NAFLD) among adolescents has been related to fructose intake. Additionally, maternal high-fat diet (mHFD) increases the offspring susceptibility to NAFLD at adulthood. Here, it is hypothesized that mHFD may exacerbate the fructose impact in adolescent male rat offspring, by changing the response of contributing mechanisms to liver injury.

METHODS AND RESULTS

Female Wistar rats receive standard (mSTD: 9% fat) or high-fat diet (mHFD: 29% fat) prior mating throughout pregnancy and lactation. After weaning, offspring receive standard chow and, from the 25th to 45th day, receive water or fructose-drinking water (15%). At 46 days old, fructose groups show increased adiposity, increased serum and hepatic triglycerides, regardless of maternal diet. Fructose aggravates the hepatic imbalance of redox state already exhibited by mHFD offspring. The hepatic activation of cellular repair pathways by fructose, such as unfolded protein response and macroautophagy, is disrupted only in mHFD offspring. Fructose does not change the liver morphology of mSTD offspring. However, it intensifies the liver injury already present in mHFD offspring.

CONCLUSION

Fructose intake during adolescence accelerates the emergence of NAFLD observed previously at the adult life of mHFD offspring, and reveals a differentiated hepatic response to metabolic insult, depending on the maternal diet.

U.S. obesity as delayed effect of excess sugar

In the last century, U.S. diets were transformed, including the addition of sugars to industrially-processed foods. While excess sugar has often been implicated in the dramatic increase in U.S. adult obesity over the past 30 years, an unexplained question is why the increase in obesity took place many years after the increases in U.S. sugar consumption. To address this, here we explain adult obesity increase as the cumulative effect of increased sugar calories consumed over time. In our model, which uses annual data on U.S. sugar consumption as the input variable, each age cohort inherits the obesity rate in the previous year plus a simple function of the mean excess sugar consumed in the current year. This simple model replicates three aspects of the data: (a) the delayed timing and magnitude of the increase in average U.S. adult obesity (from about 15% in 1970 to almost 40% by 2015); (b) the increase of obesity rates by age group (reaching 47% obesity by age 50) for the year 2015 in a well-documented U.S. state; and (c) the pre-adult increase of obesity rates by several percent from 1988 to the mid-2000s, and subsequent modest decline in obesity rates among younger children since the mid-2000s. Under this model, the sharp rise in adult obesity after 1990 reflects the delayed effects of added sugar calories consumed among children of the 1970s and 1980s.

Fat and Sugar-A Dangerous Duet. A Comparative Review on Metabolic Remodeling in Rodent Models of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a common disease in Western society and ranges from steatosis to steatohepatitis to end-stage liver disease such as cirrhosis and hepatocellular carcinoma. The molecular mechanisms that are involved in the progression of steatosis to more severe liver damage in patients are not fully understood. A deeper investigation of NAFLD pathogenesis is possible due to the many different animal models developed recently. In this review, we present a comparative overview of the most common dietary NAFLD rodent models with respect to their metabolic phenotype and morphological manifestation. Moreover, we describe similarities and controversies concerning the effect of NAFLD-inducing diets on mitochondria as well as mitochondria-derived oxidative stress in the progression of NAFLD.

Diet-Induced Rabbit Models for the Study of Metabolic Syndrome

Obesity and metabolic syndrome (MetS) have become a growing problem for public health and clinical practice, given their increased prevalence due to the rise of sedentary lifestyles and excessive caloric intake from processed food rich in fat and sugar. There are several definitions of MetS, but most of them describe it as a cluster of cardiovascular and metabolic alterations such as abdominal obesity, reduced high-density lipoprotein (HDL) and elevated low-density lipoprotein (LDL) cholesterol, elevated triglycerides, glucose intolerance, and hypertension. Diagnosis requires three out of these five criteria to be present. Despite the increasing prevalence of MetS, the understanding of its pathophysiology and relationship with disease is still limited. Indeed, the pathological consequences of MetS components have been reported individually, but investigations that have studied the effect of the combination of MeS components on organ pathological remodeling are almost nonexistent. On the other hand, animal models are a powerful tool in understanding the mechanisms that underlie pathological processes such as MetS. In the first part of the review, we will briefly overview the advantages, disadvantages and pathological manifestations of MetS in porcine, canine, rodent, and rabbit diet-induced experimental models. Then, we will focus on the different dietary regimes that have been used in rabbits to induce MetS by means of high-fat, cholesterol, sucrose or fructose-enriched diets and their effects on physiological systems and organ remodeling. Finally, we will discuss the use of dietary regimes in different transgenic strains and special rabbit breeds.

Worsening of Oxidative Stress, DNA Damage, and Atherosclerotic Lesions in Aged LDLr-/- Mice after Consumption of Guarana Soft Drinks

BACKGROUND

Excessive consumption of soft drinks (SD) has become a health problem worldwide due to its association with related cardiovascular diseases. We investigated the possible impacts associated with the consumption of Brazilian guarana (normal and zero) SD in dyslipidemic mice, thus mitigating potential clinical confounders such as poor-quality diet, lifestyle, body composition, and/or comorbidities.

METHODS

Sixteen-month-old LDLr-/- mice were divided into the following groups: (1) control; (2) GSD: normal guarana SD; and (3) Z-GSD: zero guarana SD. All were fed ad libitum, and blood pressure was measured noninvasively. After 8 weeks, aorta, blood, liver, and stomach samples were collected for histological and biochemical analyses.

RESULTS

Guarana soft drinks increased atherosclerosis (~60%) and were associated with hypercholesterolemia, hypertension, oxidative stress, DNA fragmentation, and apoptosis (~2-fold) of blood cells, besides presenting an increase in liver and gastric damage even in normoglycemia. Interestingly, Z-GSD did not cause the aforementioned changes, except in hemodynamic and renal parameters.

CONCLUSIONS

Chronic administration of GSD is prooxidative, compromising the cardiovascular, gastric, and hepatic systems; the effects are due at least in part to free sugar consumption but not to guarana extract per se.

Repercussions of low fructose-drinking water in male rats

Fructose consumption has increased worldwide, and it has been associated with the development of metabolic diseases such as insulin resistance (IR) and steatosis. The aim was to evaluate if lower fructose concentrations may cause pancreatic structural abnormalities, leading to a glucose intolerance without steatosis in male rats. Young male rats orally received 7% fructose solution for 12 weeks. Body weight, food, water, and energy intake were measured. An oral glucose tolerance test (OGTT) was performed. After final experimental period, all rats were anaesthetized and killed. Blood samples were collected for biochemical analyses and organs (liver and pancreas) were processed for morphological analyses. Fructose consumption was not associated with lipid accumulation in liver. However, fructose administration was associated with an increased area under curve from OGTT and an increased percentage of insulin-positive cells, high beta cell mass and reduced pancreatic islet area. Fructose supplementation (7%) did not cause steatosis, but it led to abnormal morphology and function of pancreatic islet cells, contributing for glucose intolerance development. Our findings demonstrate that even low fructose concentrations may cause deleterious effects in animals.

The protective effect of neonatal oral administration of oleanolic acid against the subsequent development of fructose-induced metabolic dysfunction in male and female rats

BACKGROUND

Consumption of fructose-rich diets has been implicated in the increasing global prevalence of metabolic syndrome (MetS). Interventions during periods of early ontogenic developmental plasticity can cause epigenetic changes which program metabolism for positive or negative health benefits later in life. The phytochemical oleanolic acid (OA) possesses anti-diabetic and anti-obesity effects. We investigated the potential protective effects of neonatal administration of OA on the subsequent development of high fructose diet-induced metabolic dysfunction in rats.

METHOD

Male and female (N = 112) suckling rats were randomly assigned to four groups and administered orally: distilled water (DW), oleanolic acid (OA; 60 mg/kg), high-fructose solution (HF; 20% w/v) or OA + HF for 7 days. The rats were weaned onto normal commercial rat chow up to day 55. From day 56, half of the rats in each treatment group were continued on plain water and the rest on a high fructose solution as drinking fluid for 8 weeks. On day 110, the rats were subjected to an oral glucose tolerance test and then euthanased on day 112. Tissue and blood samples were collected to determine the effects of the treatments on visceral fat pad mass, fasting plasma levels of cholesterol, insulin, glucose, triglycerides, insulin resistance (HOMA-IR) and glucose tolerance.

RESULTS

Rats which consumed fructose as neonates and then later as adults (HF + F) and those which consumed fructose only in adulthood (DW + F) had significant increases in terminal body mass (females only), visceral fat mass (males and females), serum triglycerides (females only), epididymal fat (males only), fasting plasma glucose (males and females), impaired glucose metabolism (females only), β-cell dysfunction and insulin resistance (males and females) compared to the other treatment groups (P < 0.05). There were no differences in fasting serum cholesterol levels across all treatment groups in both male and female rats (P > 0.05).

CONCLUSION

We conclude that neonatal oral administration of OA during the critical window of developmental plasticity protected against the development of health outcomes associated with fructose-induced metabolic disorders in the rats.

Involvement of glucocorticoid prereceptor metabolism and signaling in rat visceral adipose tissue lipid metabolism after chronic stress combined with high-fructose diet

Both fructose overconsumption and increased glucocorticoids secondary to chronic stress may contribute to overall dyslipidemia. In this study we specifically assessed the effects and interactions of dietary fructose and chronic stress on lipid metabolism in the visceral adipose tissue (VAT) of male Wistar rats. We analyzed the effects of 9-week 20% high fructose diet and 4-week chronic unpredictable stress, separately and in combination, on VAT histology, glucocorticoid prereceptor metabolism, glucocorticoid receptor subcellular redistribution and expression of major metabolic genes. Blood triglycerides and fatty acid composition were also measured to assess hepatic Δ9 desaturase activity. The results showed that fructose diet increased blood triglycerides and Δ9 desaturase activity. On the other hand, stress led to corticosterone elevation, glucocorticoid receptor activation and decrease in adipocyte size, while phosphoenolpyruvate carboxykinase, adipose tissue triglyceride lipase, FAT/CD36 and sterol regulatory element binding protein-1c (SREBP-1c) were increased, pointing to VAT lipolysis and glyceroneogenesis. The combination of stress and fructose diet was associated with marked stimulation of fatty acid synthase and acetyl-CoA carboxylase mRNA level and with increased 11β-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase protein levels, suggesting a coordinated increase in hexose monophosphate shunt and de novo lipogenesis. It however did not influence the level of peroxisome proliferator-activated receptor-gamma, SREBP-1c and carbohydrate responsive element-binding protein. In conclusion, our results showed that only combination of dietary fructose and stress increase glucocorticoid prereceptor metabolism and stimulates lipogenic enzyme expression suggesting that interaction between stress and fructose may be instrumental in promoting VAT expansion and dysfunction.

High-fructose corn syrup consumption in adolescent rats causes bipolar-like behavioural phenotype with hyperexcitability in hippocampal CA3-CA1 synapses

BACKGROUND AND PURPOSE

Children and adolescents are the top consumers of high-fructose corn syrup (HFCS) sweetened beverages. Even though the cardiometabolic consequences of HFCS consumption in adolescents are well known, the neuropsychiatric consequences have yet to be determined.

EXPERIMENTAL APPROACH

Adolescent rats were fed for a month with 11% weight/volume carbohydrate containing HFCS solution, which is similar to the sugar-sweetened beverages of human consumption. The metabolic, behavioural and electrophysiological characteristics of HFCS-fed rats were determined. Furthermore, the effects of TDZD-8, a highly specific GSK-3B inhibitor, on the HFCS-induced alterations were further explored.

KEY RESULTS

HFCS-fed adolescent rats displayed bipolar-like behavioural phenotype with hyperexcitability in hippocampal CA3-CA1 synapses. This hyperexcitability was associated with increased presynaptic release probability and increased readily available pool of AMPA receptors to be incorporated into the postsynaptic membrane, due to decreased expression of the neuron-specific α3-subunit of Na⁺ /K⁺ -ATPase and an increased ser⁸⁴⁵ -phosphorylation of GluA1 subunits (AMPA receptor subunit) respectively. TDZD-8 treatment was found to restore behavioural and electrophysiological disturbances associated with HFCS consumption by inhibition of GSK-3B, the most probable mechanism of action of lithium for its mood-stabilizing effects.

CONCLUSION AND IMPLICATIONS

This study shows that HFCS consumption in adolescent rats led to a bipolar-like behavioural phenotype with neuronal hyperexcitability, which is known to be one of the earliest endophenotypic manifestations of bipolar disorder. Inhibition of GSK-3B with TDZD-8 attenuated hyperexcitability and restored HFCS-induced behavioural alterations.

Metabolic Effects of Oral Phenelzine Treatment on High-Sucrose-Drinking Mice

Phenelzine has been suggested to have an antiobesity effect by inhibiting de novo lipogenesis, which led us to investigate the metabolic effects of oral chronic phenelzine treatment in high-sucrose-drinking mice. Sucrose-drinking mice presented higher body weight gain and adiposity versus controls. Phenelzine addition did not decrease such parameters, even though fat pad lipid content and weights were not different from controls. In visceral adipocytes, phenelzine did not impair insulin-stimulated de novo lipogenesis and had no effect on lipolysis. However, phenelzine reduced the mRNA levels of glucose transporters 1 and 4 and phosphoenolpyruvate carboxykinase in inguinal white adipose tissue (iWAT), and altered circulating levels of free fatty acids (FFA) and glycerol. Interestingly, glycemia was restored in phenelzine-treated mice, which also had higher insulinaemia. Phenelzine-treated mice presented higher rectal temperature, which was associated to reduced mRNA levels of uncoupling protein 1 in brown adipose tissue. Furthermore, unlike sucrose-drinking mice, hepatic malondialdehyde levels were not altered. In conclusion, although de novo lipogenesis was not inhibited by phenelzine, the data suggest that the ability to re-esterify FFA is impaired in iWAT. Moreover, the effects on glucose homeostasis and oxidative stress suggest that phenelzine could alleviate obesity-related alterations and deserves further investigation in obesity models.

A Review on the Protective Effects of Honey against Metabolic Syndrome

Metabolic syndrome (MetS) is a cluster of diseases comprising of obesity, diabetes mellitus, dyslipidemia, and hypertension. There are numerous pre-clinical as well as human studies reporting the protective effects of honey against MetS. Honey is a nutritional food low in glycemic index. Honey intake reduces blood sugar levels and prevents excessive weight gain. It also improves lipid metabolism by reducing total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) and increasing high-density lipoprotein (HDL), which leads to decreased risk of atherogenesis. In addition, honey enhances insulin sensitivity that further stabilizes blood glucose levels and protects the pancreas from overstimulation brought on by insulin resistance. Furthermore, antioxidative properties of honey help in reducing oxidative stress, which is one of the central mechanisms in MetS. Lastly, honey protects the vasculature from endothelial dysfunction and remodelling. Therefore, there is a strong potential for honey supplementation to be integrated into the management of MetS, both as preventive as well as adjunct therapeutic agents.

Potential effect of maternal dietary sucrose or fructose syrup on CD36, leptin, and ghrelin-mediated fetal programming of obesity

The influence of HFCS (high fructose corn syrup - free fructose) and sucrose (bound fructose) on fetal appetite signals is unknown. This study aimed to determine the effects of HFCS or sucrose on the peptide-mediated appetite regulation in fetal programming of obesity. Sprague Dawley female rats were administered feed and plain water (control) or water containing maltodextrin (vehicle), sucrose, fructose, or HFCS (20%, w/v) for 12 weeks before mating and throughout pregnancy and lactation (n_dams = 31; n_pups = 207). Maternal chow-feed consumption in the HFCS and sucrose groups and sugar-added drink consumption in the HFCS group were higher compared to the vehicle and control groups (P < 0.05). The total body fat accumulated in sucrose, fructose, and HFCS groups in dams and pups was higher than those in the vehicle and control groups (P < 0.05). The HFCS groups showed lower plasma leptin levels and higher ghrelin levels. Soluble CD36 levels in plasma and tongue samples were high in HFCS groups of dams and pups (P < 0.05). Rather than bound fructose, the free fructose from the maternal diet contributes to the programming of obesity through the disruption of leptin, ghrelin, and CD36 expression involved in appetite regulation.

Conversion of Sugar to Fat: Is Hepatic de Novo Lipogenesis Leading to Metabolic Syndrome and Associated Chronic Diseases?

Epidemiologic studies suggest a link between excess sugar consumption and obesity, fatty liver disease, metabolic syndrome, and type 2 diabetes mellitus. One important pathway that may link these metabolic diseases to sugar consumption is hepatic conversion of sugar to fat, a process known as de novo lipogenesis (DNL). Mechanistic studies have shown that diets high in simple sugars increase both DNL and liver fat. Importantly, removal of sugar from diets of children with obesity for only 9 days consistently reduced DNL and liver fat and improved glucose and lipid metabolism. Although the sugar and beverage industries continue to question the scientific evidence linking high-sugar diets to metabolic diseases, major health organizations now make evidence-based recommendations to limit consumption of simple sugars to no more than 5% to 10% of daily intake. Clear recommendation about moderating sugar intake to patients may be an important nonpharmacologic tool to include in clinical practice.

Oral administration of fructose exacerbates liver fibrosis and hepatocarcinogenesis via increased intestinal permeability in a rat steatohepatitis model

Recent reports have revealed the impact of a western diet containing large amounts of fructose on the pathogenesis of non-alcoholic steatohepatitis (NASH). Fructose exacerbates hepatic inflammation in NASH by inducing increasing intestinal permeability. However, it is not clear whether fructose contributes to the progression of liver fibrosis and hepatocarcinogenesis in NASH. The aim of this study was to investigate the effect of fructose intake on NASH in a rat model. A choline-deficient/L-amino acid diet was fed to F344 rats to induce NASH. Fructose was administrated to one group in the drinking water. The development of liver fibrosis and hepatocarcinogenesis were evaluated histologically. Oral fructose administration exacerbated liver fibrosis and increased the number of preneoplastic lesions positive for glutathione S-transferase placental form. Fructose-treated rats had significantly higher expression of hepatic genes related to toll-like receptor-signaling, suggesting that fructose consumption increased signaling in this pathway, leading to the progression of NASH. We confirmed that intestinal permeability was significantly higher in fructose-treated rats, as evidenced by a loss of intestinal tight junction proteins. Fructose exacerbated both liver fibrosis and hepatocarcinogenesis by increasing intestinal permeability. This observation strongly supports the role of endotoxin in the progression of NASH.

Animal models of obesity and diabetes mellitus

More than one-third of the worldwide population is overweight or obese and therefore at risk of developing type 2 diabetes mellitus. In order to mitigate this pandemic, safer and more potent therapeutics are urgently required. This necessitates the continued use of animal models to discover, validate and optimize novel therapeutics for their safe use in humans. In order to improve the transition from bench to bedside, researchers must not only carefully select the appropriate model but also draw the right conclusions. In this Review, we consolidate the key information on the currently available animal models of obesity and diabetes and highlight the advantages, limitations and important caveats of each of these models.

High fructose diet-induced metabolic syndrome: Pathophysiological mechanism and treatment by traditional Chinese medicine

Fructose is a natural monosaccharide broadly used in modern society. Over the past few decades, epidemiological studies have demonstrated that high fructose intake is an etiological factor of metabolic syndrome (MetS). This review highlights research advances on fructose-induced MetS, especially the underlying pathophysiological mechanism as well as pharmacotherapy by traditional Chinese medicine (TCM), using the PubMed, Web of science, China National Knowledge Infrastructure, China Science and Technology Journal and Wanfang Data. This review focuses on de novo lipogenesis (DNL) and uric acid (UA) production, two unique features of fructolysis different from glucose glycolysis. High level of DNL and UA production can result in insulin resistance, the key pathological event in developing MetS, mostly through oxidative stress and inflammation. Some other pathologies like the disturbance in brain and gut microbiota in the development of fructose-induced MetS in the past years, are also discussed. In management of MetS, TCM is an excellent representative in alternative and complementary medicine with a complete theory system and substantial herbal remedies. TCMs against MetS or MetS components, including Chinese patent medicines, TCM compound formulas, single TCM herbs and active compounds of TCM herbs, are reviewed on their effects and molecular mechanisms. TCMs with hypouricemic activity, which specially target fructose-induced MetS, are highlighted. And new technologies and strategies (such as high-throughput assay and systems biology) in this field are further discussed. In summary, fructose-induced MetS is a multifactorial disorder with the underlying complex mechanisms. Current clinical and pre-clinical evidence supports the potential of TCMs in management of MetS. Additionally, TCMs may show some advantages against complex MetS as their holistic feature through multiple target actions. However, further work is needed to confirm the effectivity and safety of TCMs by high-standard clinical trials, clarify the molecular mechanisms, and develop new anti-MetS drugs by development and application of optimized and feasible strategies and methods.

Obesity, Metabolism, and Aging: A Multiscalar Approach

Obesity contributes to the aging process through the alteration of metabolic pathways evidenced biochemically in the relationship between caloric restriction and longevity. Humans have entered into an era of metabolism and aging entirely unprecedented in their evolution, with a diet that, for many, contains a majority of calories as sugar and yields an expected lifespan of over 80years in industrialized nations. Deeply embedded in the complex issue of obesity are questions of behavior, causality versus correlation, and appropriate models. For example, are primates a better reference than mice for studying metabolic connections between obesity and aging? We consider those issues from the standpoint of life-history theory, especially implications of the interplay of refined sugar and socioeconomic disparities for the future of human health.

Magnetic resonance spectroscopy detects differential lipid composition in mammary glands on low fat, high animal fat versus high fructose diets

The effects of consumption of different diets on the fatty acid composition in the mammary glands of SV40 T-antigen (Tag) transgenic mice, a well-established model of human triple-negative breast cancer, were investigated with magnetic resonance spectroscopy and spectroscopic imaging. Female C3(1) SV40 Tag transgenic mice (n = 12) were divided into three groups at 4 weeks of age: low fat diet (LFD), high animal fat diet (HAFD), and high fructose diet (HFruD). MRI scans of mammary glands were acquired with a 9.4 T scanner after 8 weeks on the diet. 1H spectra were acquired using point resolved spectroscopy (PRESS) from two 1 mm3 boxes on each side of inguinal mammary gland with no cancers, lymph nodes, or lymph ducts. High spectral and spatial resolution (HiSS) images were also acquired from nine 1-mm slices. A combination of Gaussian and Lorentzian functions was used to fit the spectra. The percentages of poly-unsaturated fatty acids (PUFA), mono-unsaturated fatty acids (MUFA), and saturated fatty acids (SFA) were calculated from each fitted spectrum. Water and fat peak height images (maps) were generated from HiSS data. The results showed that HAFD mice had significantly lower PUFA than both LFD (p < 0.001) and HFruD (p < 0.01) mice. The mammary lipid quantity calculated from 1H spectra was much larger in HAFD mice than in LFD (p = 0.03) but similar to HFruD mice (p = 0.10). The average fat signal intensity over the mammary glands calculated from HiSS fat maps was ~60% higher in HAFD mice than in LFD (p = 0.04) mice. The mean or median of calculated parameters for the HFruD mice were between those for LFD and HAFD mice. Therefore, PRESS spectroscopy and HiSS MRI demonstrated water and fat composition changes in mammary glands due to a Western diet, which was low in potassium, high in sodium, animal fat, and simple carbohydrates. Measurements of PUFA with MRI could be used to evaluate cancer risk, improve cancer detection and diagnosis, and guide preventative therapy.

High fructose corn syrup induces metabolic dysregulation and altered dopamine signaling in the absence of obesity

The contribution of high fructose corn syrup (HFCS) to metabolic disorder and obesity, independent of high fat, energy-rich diets, is controversial. While high-fat diets are widely accepted as a rodent model of diet-induced obesity (DIO) and metabolic disorder, the value of HFCS alone as a rodent model of DIO is unclear. Impaired dopamine function is associated with obesity and high fat diet, but the effect of HFCS on the dopamine system has not been investigated. The objective of this study was to test the effect of HFCS on weight gain, glucose regulation, and evoked dopamine release using fast-scan cyclic voltammetry. Mice (C57BL/6) received either water or 10% HFCS solution in combination with ad libitum chow for 15 weeks. HFCS consumption with chow diet did not induce weight gain compared to water, chow-only controls but did induce glucose dysregulation and reduced evoked dopamine release in the dorsolateral striatum. These data show that HFCS can contribute to metabolic disorder and altered dopamine function independent of weight gain and high-fat diets.

Rare Sugar Syrup Containing d-Allulose but Not High-Fructose Corn Syrup Maintains Glucose Tolerance and Insulin Sensitivity Partly via Hepatic Glucokinase Translocation in Wistar Rats

Ingestion of high-fructose corn syrup (HFCS) is associated with the risk of both diabetes and obesity. Rare sugar syrup (RSS) has been developed by alkaline isomerization of HFCS and has anti-obesity and anti-diabetic effects. However, the influence of RSS on glucose metabolism has not been explored. We investigated whether long-term administration of RSS maintains glucose tolerance and whether the underlying mechanism involves hepatic glucokinase translocation. Wistar rats were administered water, RSS, or HFCS in drinking water for 10 weeks and then evaluated for glucose tolerance, insulin tolerance, liver glycogen content, and subcellular distribution of liver glucokinase. RSS significantly suppressed body weight gain and abdominal fat mass (p < 0.05). The glucose tolerance test revealed significantly higher blood glucose levels in the HFCS group compared to the water group, whereas the RSS group had significantly lower blood glucose levels from 90 to 180 min (p < 0.05). At 30, 60, and 90 min, the levels of insulin in the RSS group were significantly lower than those in the water group (p < 0.05). The amount of hepatic glycogen was more than 3 times higher in the RSS group than that in the other groups. After glucose loading, the nuclear export of glucokinase was significantly increased in the RSS group compared to the water group. These results imply that RSS maintains glucose tolerance and insulin sensitivity, at least partly, by enhancing nuclear export of hepatic glucokinase.

High Dietary Fructose: Direct or Indirect Dangerous Factors Disturbing Tissue and Organ Functions

High dietary fructose is a major contributor to insulin resistance and metabolic syndrome, disturbing tissue and organ functions. Fructose is mainly absorbed into systemic circulation by glucose transporter 2 (GLUT2) and GLUT5, and metabolized in liver to produce glucose, lactate, triglyceride (TG), free fatty acid (FFA), uric acid (UA) and methylglyoxal (MG). Its extrahepatic absorption and metabolism also take place. High levels of these metabolites are the direct dangerous factors. During fructose metabolism, ATP depletion occurs and induces oxidative stress and inflammatory response, disturbing functions of local tissues and organs to overproduce inflammatory cytokine, adiponectin, leptin and endotoxin, which act as indirect dangerous factors. Fructose and its metabolites directly and/or indirectly cause oxidative stress, chronic inflammation, endothelial dysfunction, autophagy and increased intestinal permeability, and then further aggravate the metabolic syndrome with tissue and organ dysfunctions. Therefore, this review addresses fructose-induced metabolic syndrome, and the disturbance effects of direct and/or indirect dangerous factors on the functions of liver, adipose, pancreas islet, skeletal muscle, kidney, heart, brain and small intestine. It is important to find the potential correlations between direct and/or indirect risk factors and healthy problems under excess dietary fructose consumption.

Metabolic effects of intermittent access to caloric or non-caloric sweetened solutions in mice fed a high-caloric diet

Human consumption of obesogenic diets and soft drinks, sweetened with different molecules, is increasing worldwide, and increases the risk of metabolic diseases. We hypothesized that the chronic consumption of caloric (sucrose, high-fructose corn syrup (HFCS), maltodextrin) and non-caloric (sucralose) solutions under 2-hour intermittent access, alongside the consumption of a high-fat high-sucrose diet, would result in differential obesity-associated metabolic abnormalities in mice. Male C57BL/6 mice had ad libitum access to an HFHS diet and to water (water control group). In addition, some mice had access, 2h/day, 5days/week (randomly chosen) for 12weeks, to different solutions: i) a sucrose solution (2.1kJ/ml), ii) an HFCS solution (2.1kJ/ml), iii) a maltodextrin solution (2.1kJ/ml) and a sucralose solution (60mM) (n=15/group). Despite no changes in total caloric intake, 2h-intermittent access to the sucrose, HFCS or maltodextrin solutions led to increased body weight and accumulation of lipids in the liver when compared to the group consuming water only. The HFCS and sucrose solutions induced a higher fat mass in various fat depots, glucose intolerance, increased glucose oxidation at the expense of lipid oxidation, and a lower hypothalamic expression of NPY in the fasted state. HFCS also reduced proopiomelanocortin expression in the hypothalamus. 2h-intermittent access to sucralose did not result in significant changes in body composition, but caused a stronger expression of CART in the hypothalamus. Finally, sucrose intake showed a trend to increase the expression of various receptors in the nucleus accumbens, linked to dopamine, opioid and endocannabinoid signaling. In conclusion, 2h-intermittent access to caloric solutions (especially those sweetened with sucrose and HFCS), but not sucralose, resulted in adverse metabolic consequences in high-fat high-sucrose-fed mice.

Animal models of metabolic syndrome: a review

Metabolic syndrome (MetS) consists of several medical conditions that collectively predict the risk for cardiovascular disease better than the sum of individual conditions. The risk of developing MetS in human depends on synergy of both genetic and environmental factors. Being a multifactorial condition with alarming rate of prevalence nowadays, establishment of appropriate experimental animal models mimicking the disease state in humans is crucial in order to solve the difficulties in evaluating the pathophysiology of MetS in human. This review aims to summarize the underlying mechanisms involved in the pathophysiology of dietary, genetic, and pharmacological models of MetS. Furthermore, we will discuss the usefulness, suitability, pros and cons of these animal models. Even though numerous animal models of MetS have been established, further investigations on the invention of new animal model and clarification of plausible mechanisms are still necessary to confer a better understanding to researchers on the selection of animal models for their studies.

High-fructose corn syrup-55 consumption alters hepatic lipid metabolism and promotes triglyceride accumulation

High-fructose corn syrup-55 (HFCS-55) has been suggested to be more lipogenic than sucrose, which increases the risk for nonalcoholic fatty liver disease (NAFLD) and dyslipidemia. The study objectives were to determine the effects of drinking different sugar-sweetened solutions on hepatic gene expression in relation to liver fatty acid composition and risk of NAFLD. Female rats were randomly assigned (n=7 rats/group) to drink water or water sweetened with 13% (w/v) HFCS-55, sucrose or fructose for 8 weeks. Rats drinking HFCS-55 solution had the highest (P=.03) hepatic total lipid and triglyceride content and histological evidence of fat infiltration. Rats drinking HFCS-55 solution had the highest hepatic de novo lipogenesis indicated by the up-regulation of stearoyl-CoA desaturase-1 and the highest (P<.001) oleic acid (18:1n-9) content. This was accompanied by reduced β-oxidation indicated by down-regulation of hepatic peroxisome proliferator-activated receptor α. Disposal of excess lipids by export of triglyceride-rich lipoprotein from the liver was increased as shown by up-regulation of gene expression of microsomal triglyceride transfer protein in rats drinking sucrose, but not HFCS-55 solution. The observed lipogenic effects were attributed to the slightly higher fructose content of HFCS-55 solution in the absence of differences in macronutrient and total caloric intake between rats drinking HFCS-55 and sucrose solution. Results from gene expression and fatty acid composition analysis showed that, in a hypercaloric state, some types of sugars are more detrimental to the liver. Based on these preclinical study results, excess consumption of caloric sweetened beverage, particularly HFCS-sweetened beverages, should be limited.

Fructose Beverage Consumption Induces a Metabolic Syndrome Phenotype in the Rat: A Systematic Review and Meta-Analysis

A high intake of refined carbohydrates, particularly the monosaccharide fructose, has been attributed to the growing epidemics of obesity and type-2 diabetes. Animal studies have helped elucidate the metabolic effects of dietary fructose, however, variations in study design make it difficult to draw conclusions. The aim of this study was to review the effects of fructose beverage consumption on body weight, systolic blood pressure and blood glucose, insulin and triglyceride concentrations in validated rat models. We searched Ovid Embase Classic + EmbaseMedline and Ovid Medline databases and included studies that used adolescent/adult male rats, with fructose beverage consumption for >3 weeks. Data from 26 studies were pooled by an inverse variance weighting method using random effects models, expressed as standardized mean differences (SMD) with 95% confidence intervals (CI). Overall, 10%–21% w/v fructose beverage consumption was associated with increased rodent body weight (SMD, 0.62 (95% CI: 0.18, 1.06)), systolic blood pressure (SMD, 2.94 (95% CI: 2.10, 3.77)) and blood glucose (SMD, 0.77 (95% CI: 0.36, 1.19)), insulin (SMD, 2.32 (95% CI: 1.57, 3.07)) and triglyceride (SMD, 1.87 (95% CI: 1.39, 2.34)) concentrations. Therefore, the consumption of a low concentration fructose beverage is sufficient to cause early signs of the metabolic syndrome in adult rats.

High-fructose diet in pregnancy leads to fetal programming of hypertension, insulin resistance, and obesity in adult offspring

BACKGROUND

Consumption of fructose-rich diets in the United States is on the rise and thought to be associated with obesity and cardiometabolic diseases.

OBJECTIVE

We sought to determine the effects of antenatal exposure to high-fructose diet on offspring's development of metabolic syndrome-like phenotype and other cardiovascular disease risk factors later in life.

STUDY DESIGN

Pregnant C57BL/6J dams were randomly allocated to fructose solution (10% wt/vol, n = 10) or water (n = 10) as the only drinking fluid from day 1 of pregnancy until delivery. After weaning, pups were started on regular chow, and evaluated at 1 year of life. We measured percent visceral adipose tissue and liver fat infiltrates using computed tomography, and blood pressure using CODA nonivasive monitor. Intraperitoneal glucose tolerance testing with corresponding insulin concentrations were obtained. Serum concentrations of glucose, insulin, triglycerides, total cholesterol, leptin, and adiponectin were measured in duplicate using standardized assays. Fasting homeostatic model assessment was also calculated to assess insulin resistance. P values <.05 were considered statistically significant.

RESULTS

Maternal weight, pup number, and average weight at birth were similar between the 2 groups. Male and female fructose group offspring had higher peak glucose and area under the intraperitoneal glucose tolerance testing curve compared with control, and higher mean arterial pressure compared to control. Female fructose group offspring were heavier and had higher percent visceral adipose tissue, liver fat infiltrates, homeostatic model assessment of insulin resistance scores, insulin area under the intraperitoneal glucose tolerance testing curve, and serum concentrations of leptin, and lower concentrations of adiponectin compared to female control offspring. No significant differences in these parameters were noted in male offspring. Serum concentrations of triglycerides or total cholesterol were not different between the 2 groups for either gender.

CONCLUSION

Maternal intake of high fructose leads to fetal programming of adult obesity, hypertension, and metabolic dysfunction, all risk factors for cardiovascular disease. This fetal programming is more pronounced in female offspring. Limiting intake of high fructose-enriched diets in pregnancy may have significant impact on long-term health.

Dietary Fructose and GLUT5 Transporter Activity Contribute to Antipsychotic-Induced Weight Gain

Receptors for antipsychotics in the hypothalamus contribute to antipsychotics-induced weight gain; however, many of these receptors are also expressed in the intestine. The role of these intestinally-expressed receptors, and their potential modulation of nutrient absorption, have not been investigated in the context of antipsychotics-induced weight gain. Here we tested the effect of dietary fructose and intestinal fructose uptake on clozapine-induced weight gain in mice. Weight gain was determined in wild type mice and mice lacking the GLUT5 fructose transporter that were "orally-administered" 20mg/kg clozapine for 28 days. To assess the role of dietary fructose, clozapine-treated mice were fed controlled diets with different levels of fructose. Effect of clozapine treatment on intestinal fructose transport activity and expression levels of various receptors that bind clozapine, as well as several genes involved in gluconeogenesis and lipogenesis were measured using real-time RT-PCR and western blotting. Oral administration of clozapine significantly increased body weight in wild type C57BL/6 mice but not in GLUT5 null mice. The clozapine-induced weight gain was proportional to the percentage of fructose in the diet. Clozapine-treated mice increased intestinal fructose uptake without changing the intestinal expression level of GLUT5. Clozapine-treated mice expressed significantly higher levels of intestinal H1 histamine receptor in the wild type but not GLUT5 null mice. Clozapine also increased the intestinal expression of fructokinase and several genes involved in gluconeogenesis and lipogenesis. Our results suggest that increased intestinal absorption and metabolism of fructose contributes to clozapine-induced weight gain. Eliminating dietary fructose might prevent antipsychotics-induced weight gain.

Novelty in hypertension in children and adolescents: focus on hypertension during the first year of life, use and interpretation of ambulatory blood pressure monitoring, role of physical activity in prevention and treatment, simple carbohydrates and uric acid as risk factors

The present article intends to provide an update of the article "Focus on prevention, diagnosis and treatment of hypertension in children and adolescents" published in 2013 (Spagnolo et al., Ital J Pediatr 39:20, 2013) in this journal. This revision is justified by the fact that during the last years there have been several new scientific contributions to the problem of hypertension in pediatric age and during adolescence. Nevertheless, for what regards some aspects of the previous article, the newly acquired information did not require substantial changes to what was already published, both from a cultural and from a clinical point of view. We felt, however, the necessity to rewrite and/or to extend other parts in the light of the most recent scientific publications. More specifically, we updated and extended the chapters on the diagnosis and management of hypertension in newborns and unweaned babies, on the use and interpretation of ambulatory blood pressure monitoring, and on the usefulness of and indications for physical activity. Furthermore, we added an entirely new section on the role that simple carbohydrates (fructose in particular) and uric acid may play in the pathogenesis of hypertension in pediatric age.

Effects of Excess Energy Intake on Glucose and Lipid Metabolism in C57BL/6 Mice

Excess energy intake correlates with the development of metabolic disorders. However, different energy-dense foods have different effects on metabolism. To compare the effects of a high-fat diet, a high-fructose diet and a combination high-fat/high-fructose diet on glucose and lipid metabolism, male C57BL/6 mice were fed with one of four different diets for 3 months: standard chow; standard diet and access to fructose water; a high fat diet; and a high fat diet with fructose water. After 3 months of feeding, the high-fat and the combined high-fat/high-fructose groups showed significantly increased body weights, accompanied by hyperglycemia and insulin resistance; however, the high-fructose group was not different from the control group. All three energy-dense groups showed significantly higher visceral fat weights, total cholesterol concentrations, and low-density lipoprotein cholesterol concentrations compared with the control group. Assays of basal metabolism showed that the respiratory quotient of the high-fat, the high-fructose, and the high-fat/high-fructose groups decreased compared with the control group. The present study confirmed the deleterious effect of high energy diets on body weight and metabolism, but suggested that the energy efficiency of the high-fructose diet was much lower than that of the high-fat diet. In addition, fructose supplementation did not worsen the detrimental effects of high-fat feeding alone on metabolism in C57BL/6 mice.

Differential Responses of Plasma Adropin Concentrations To Dietary Glucose or Fructose Consumption In Humans

Adropin is a peptide hormone encoded by the Energy Homeostasis Associated (ENHO) gene whose physiological role in humans remains incompletely defined. Here we investigated the impact of dietary interventions that affect systemic glucose and lipid metabolism on plasma adropin concentrations in humans. Consumption of glucose or fructose as 25% of daily energy requirements (E) differentially affected plasma adropin concentrations (P < 0.005) irrespective of duration, sex or age. Glucose consumption reduced plasma adropin from 3.55 ± 0.26 to 3.28 ± 0.23 ng/ml (N = 42). Fructose consumption increased plasma adropin from 3.63 ± 0.29 to 3.93 ± 0.34 ng/ml (N = 45). Consumption of high fructose corn syrup (HFCS) as 25% E had no effect (3.43 ± 0.32 versus 3.39 ± 0.24 ng/ml, N = 26). Overall, the effect of glucose, HFCS and fructose on circulating adropin concentrations were similar to those observed on postprandial plasma triglyceride concentrations. Furthermore, increases in plasma adropin levels with fructose intake were most robust in individuals exhibiting hypertriglyceridemia. Individuals with low plasma adropin concentrations also exhibited rapid increases in plasma levels following consumption of breakfasts supplemented with lipids. These are the first results linking plasma adropin levels with dietary sugar intake in humans, with the impact of fructose consumption linked to systemic triglyceride metabolism. In addition, dietary fat intake may also increase circulating adropin concentrations.

Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies

By reducing energy density, low-energy sweeteners (LES) might be expected to reduce energy intake (EI) and body weight (BW). To assess the totality of the evidence testing the null hypothesis that LES exposure (versus sugars or unsweetened alternatives) has no effect on EI or BW, we conducted a systematic review of relevant studies in animals and humans consuming LES with ad libitum access to food energy. In 62 of 90 animal studies exposure to LES did not affect or decreased BW. Of 28 reporting increased BW, 19 compared LES with glucose exposure using a specific ‘learning' paradigm. Twelve prospective cohort studies in humans reported inconsistent associations between LES use and body mass index (−0.002 kg m⁻² per year, 95% confidence interval (CI) −0.009 to 0.005). Meta-analysis of short-term randomized controlled trials (129 comparisons) showed reduced total EI for LES versus sugar-sweetened food or beverage consumption before an ad libitum meal (−94 kcal, 95% CI −122 to −66), with no difference versus water (−2 kcal, 95% CI −30 to 26). This was consistent with EI results from sustained intervention randomized controlled trials (10 comparisons). Meta-analysis of sustained intervention randomized controlled trials (4 weeks to 40 months) showed that consumption of LES versus sugar led to relatively reduced BW (nine comparisons; −1.35 kg, 95% CI –2.28 to −0.42), and a similar relative reduction in BW versus water (three comparisons; −1.24 kg, 95% CI –2.22 to −0.26). Most animal studies did not mimic LES consumption by humans, and reverse causation may influence the results of prospective cohort studies. The preponderance of evidence from all human randomized controlled trials indicates that LES do not increase EI or BW, whether compared with caloric or non-caloric (for example, water) control conditions. Overall, the balance of evidence indicates that use of LES in place of sugar, in children and adults, leads to reduced EI and BW, and possibly also when compared with water.

Sugar-Sweetened Beverage Consumption Is Associated with Metabolic Syndrome in Iranian Adults: Tehran Lipid and Glucose Study

BACKGROUND

Metabolic syndrome (MetS), a cluster of multiple metabolic abnormalities, is one of the major public health challenges worldwide. The current study was conducted to evaluate the association between sugar-sweetened beverage (SSB) consumption and MetS and its components in Iranian adults.

METHODS

This cross-sectional study was conducted among 5,852 men and women, aged 19 to 70 years, who participated in the fourth phase (2009 to 2011) of the Tehran Lipid and Glucose Study. Demographics, anthropometrics, biochemical measurements, and blood pressure (BP) were assessed and MetS was defined by National Cholesterol Education Program Adult Treatment Panel III definition. Frequency and quantity of SSB intakes including carbonated drinks and synthetic fruit juices were collected using a validated semiquantitative food frequency questionnaire.

RESULTS

Mean age of participants (43%, men) was 40.6±12.9 years. Significant positive associations between SSBs and waist circumference, triglyceride level, systolic and diastolic BP in the third and fourth quartile of SSBs were observed, after adjustment for all potential confounding variables. The odds of MetS in the third and fourth quartiles compared to the first quartile category of SSBs was 1.21 (95% confidence interval [CI], 1.01 to 1.45) and 1.30 (95% CI, 1.06 to 1.58), respectively (P for trend=0.03). The odds of MetS, abdominal obesity, low high density lipoprotein cholesterol and elevated BP had increasing trends across increasing of SSB consumption (P for trend <0.05).

CONCLUSION

Higher intake of SSBs was associated with the higher odds of MetS in adults. It is suggested that reducing consumption of SSBs could be a practical approach to prevent metabolic abnormalities.

Soybean Oil Is More Obesogenic and Diabetogenic than Coconut Oil and Fructose in Mouse: Potential Role for the Liver

The obesity epidemic in the U.S. has led to extensive research into potential contributing dietary factors, especially fat and fructose. Recently, increased consumption of soybean oil, which is rich in polyunsaturated fatty acids (PUFAs), has been proposed to play a causal role in the epidemic. Here, we designed a series of four isocaloric diets (HFD, SO-HFD, F-HFD, F-SO-HFD) to investigate the effects of saturated versus unsaturated fat, as well as fructose, on obesity and diabetes. C57/BL6 male mice fed a diet moderately high in fat from coconut oil and soybean oil (SO-HFD, 40% kcal total fat) showed statistically significant increases in weight gain, adiposity, diabetes, glucose intolerance and insulin resistance compared to mice on a diet consisting primarily of coconut oil (HFD). They also had fatty livers with hepatocyte ballooning and very large lipid droplets as well as shorter colonic crypt length. While the high fructose diet (F-HFD) did not cause as much obesity or diabetes as SO-HFD, it did cause rectal prolapse and a very fatty liver, but no balloon injury. The coconut oil diet (with or without fructose) increased spleen weight while fructose in the presence of soybean oil increased kidney weight. Metabolomics analysis of the liver showed an increased accumulation of PUFAs and their metabolites as well as γ-tocopherol, but a decrease in cholesterol in SO-HFD. Liver transcriptomics analysis revealed a global dysregulation of cytochrome P450 (Cyp) genes in SO-HFD versus HFD livers, most notably in the Cyp3a and Cyp2c families. Other genes involved in obesity (e.g., Cidec, Cd36), diabetes (Igfbp1), inflammation (Cd63), mitochondrial function (Pdk4) and cancer (H19) were also upregulated by the soybean oil diet. Taken together, our results indicate that in mice a diet high in soybean oil is more detrimental to metabolic health than a diet high in fructose or coconut oil.

Fructose Alters Intermediary Metabolism of Glucose in Human Adipocytes and Diverts Glucose to Serine Oxidation in the One-Carbon Cycle Energy Producing Pathway

Increased consumption of sugar and fructose as sweeteners has resulted in the utilization of fructose as an alternative metabolic fuel that may compete with glucose and alter its metabolism. To explore this, human Simpson-Golabi-Behmel Syndrome (SGBS) preadipocytes were differentiated to adipocytes in the presence of 0, 1, 2.5, 5 or 10 mM of fructose added to a medium containing 5 mM of glucose representing the normal blood glucose concentration. Targeted tracer [1,2-¹³C₂]-d-glucose fate association approach was employed to examine the influence of fructose on the intermediary metabolism of glucose. Increasing concentrations of fructose robustly increased the oxidation of [1,2-¹³C₂]-d-glucose to ¹³CO₂ (p < 0.000001). However, glucose-derived ¹³CO₂ negatively correlated with ¹³C labeled glutamate, ¹³C palmitate, and M₊₁ labeled lactate. These are strong markers of limited tricarboxylic acid (TCA) cycle, fatty acid synthesis, pentose cycle fluxes, substrate turnover and NAD⁺/NADP⁺ or ATP production from glucose via complete oxidation, indicating diminished mitochondrial energy metabolism. Contrarily, a positive correlation was observed between glucose-derived ¹³CO₂ formed and ¹³C oleate and doses of fructose which indicate the elongation and desaturation of palmitate to oleate for storage. Collectively, these results suggest that fructose preferentially drives glucose through serine oxidation glycine cleavage (SOGC pathway) one-carbon cycle for NAD⁺/NADP⁺ production that is utilized in fructose-induced lipogenesis and storage in adipocytes.

Standard short-term diet ameliorates the lipid profile altered by a fructose-rich diet in rats

Markers of metabolic abnormalities are commonly found in rodents fed a fructose-rich diet. The purpose of this study was to determine whether the administration of a short-term standard diet to rats is able to improve the lipid profile altered by a fructose-rich diet. The male pups, immediately after birth, were divided in three groups according to the diet for 90 days. Standard diet: a standard diet for the whole experimental period; fructose (60% fructose-rich diet): fructose-rich diet during the entire experimental period; fructose/standard (FS): fructose-rich diet from the neonatal period up to 60 days of age and standard diet from 60 to 90 days of age. A fructose-rich diet from the neonatal period to 60 days reduced weight gain (P<0.05), as well as the weight of adipose tissues in all the regions analyzed (epididymal, mesenteric, retroperitoneal and posterior subcutaneous), and it altered the lipid profile (elevation of triglycerides, total cholesterol, low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) cholesterol; P<0.05). When a standard diet was administered after the fructose-rich diet, it was able to partially reverse changes to the lipid profile, as total cholesterol levels were significantly different in all the groups (P<0.05), and triglyceride and VLDL cholesterol levels were similar between the control and FS group. In summary, a fructose-rich diet altered the lipid profile, and a standard diet can partially reverse the changed parameters in short term.

Compared to sucrose, previous consumption of fructose and glucose monosaccharides reduces survival and fitness of female mice

BACKGROUND

Intake of added sugar has been shown to correlate with many human metabolic diseases, and rodent models have characterized numerous aspects of the resulting disease phenotypes. However, there is a controversy about whether differential health effects occur because of the consumption of either of the two common types of added sugar-high-fructose corn syrup (fructose and glucose monosaccharides; F/G) or table sugar (sucrose, a fructose and glucose disaccharide).

OBJECTIVES

We tested the equivalence of sucrose- vs. F/G-containing diets on mouse (Mus musculus) longevity, reproductive success, and social dominance.

METHODS

We fed wild-derived mice, outbred mice descended from wild-caught ancestors, a diet in which 25% of the calories came from either an equal ratio of F/G or an isocaloric amount of sucrose (both diets had 63% of total calories as carbohydrates). Exposure lasted 40 wk, starting at weaning (21 d of age), and then mice (104 females and 56 males) were released into organismal performances assays-seminatural enclosures where mice competed for territories, resources, and mates for 32 wk. Within enclosures all mice consumed the F/G diet.

RESULTS

Females initially fed the F/G diet experienced a mortality rate 1.9 times the rate (P = 0.012) and produced 26.4% fewer offspring than females initially fed sucrose (P = 0.001). This reproductive deficiency was present before mortality differences, suggesting the F/G diet was causing physiologic performance deficits prior to mortality. No differential patterns in survival, reproduction, or social dominance were observed in males, indicating a sex-specific outcome of exposure.

CONCLUSION

This study provides experimental evidence that the consumption of human-relevant levels of F/G is more deleterious than an isocaloric amount of sucrose for key organism-level health measures in female mice.