The effect of a low fructose and low glycemic index/load (FRAGILE) dietary intervention on indices of liver function, cardiometabolic risk factors, and body composition in children and adolescents with nonalcoholic fatty liver disease (NAFLD)

Insulinotropic Effect of S-Allyl Cysteine in Rat Pups

S-Allyl cysteine (SAC) is found in garlic and has been reported to exert antidiabetic and antiobesity properties in drug-induced adult experimental models of metabolic dysfunction, but its potential beneficial effects in high-fructose diet neonatal rat models have not been determined. This study investigated the potential prophylactic effects of SAC in high-fructose diet fed suckling rat pups modelling human neonates fed a high-fructose diet. Four-day-old male (n=32) and female (n=32) Wistar rat pups, were randomly assigned to and administered the following treatment regimens daily for 15 days: group I, distilled water; group II, 20% fructose solution (FS); group III, SAC; group IV, SAC+FS. The pups' blood glucose, triglyceride, cholesterol, plasma leptin and insulin concentration, liver lipid content, and liver histology were determined at termination. In female rat pups, orally administered SAC prevented FS-induced hypoinsulinemia but significantly increased (P≤0.05) liver lipid content. Oral administration of SAC significantly increased (P≤0.05) plasma insulin concentration and homeostasis model assessment for insulin resistance in the male pups. The potential sexually dimorphic effects of SAC (insulinotropic effects in male pups and protection of female pups against fructose-induced hypoinsulinemia) suggest that SAC could be potentially exploited as an antidiabetic and insulinotropic agent. Caution should, however, be exercised in the use of SAC during suckling as it could result in excessive liver lipid accumulation and insulin resistance.

An Overview of Dietary Interventions and Strategies to Optimize the Management of Non-Alcoholic Fatty Liver Disease

Aim: To investigate the efficacy of lifestyle adjustment strategies as a preventive measure and/or treatment of obesity-related non-alcoholic fatty liver disease in adults. Method: A systematic review of literature through 1 July 2017 on the PubMed Database was performed. A comprehensive search was conducted using key terms, such as non-alcoholic fatty liver disease (NAFLD), combined with lifestyle intervention, diet, and exercise. All of the articles and studies obtained from the search were reviewed. Redundant literature was excluded. Results: Several types of dietary compositions and exercise techniques were identified. Most studies concluded and recommended reduction in the intake of saturated and trans fatty acids, carbohydrates, and animal-based protein, and increased intake of polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs), plant-based proteins, antioxidants, and other nutrients was recommended. The Mediterranean and Paleo diet both seem to be promising schemes for NAFLD patients to follow. Exercise was also encouraged, but the type of exercise did not affect its efficacy as a NAFLD treatment when the duration is consistent. Conclusions: Although these different dietary strategies and exercise regimens can be adopted to treat NAFLD, current literature on the topic is limited in scope. Further research should be conducted to truly elucidate which lifestyle adjustments individually, and in combination, may facilitate patients with obesity-related NAFLD.

Divergent effects of glucose and fructose on hepatic lipogenesis and insulin signaling

Overconsumption of high-fat diet (HFD) and sugar-sweetened beverages are risk factors for developing obesity, insulin resistance, and fatty liver disease. Here we have dissected mechanisms underlying this association using mice fed either chow or HFD with or without fructose- or glucose-supplemented water. In chow-fed mice, there was no major physiological difference between fructose and glucose supplementation. On the other hand, mice on HFD supplemented with fructose developed more pronounced obesity, glucose intolerance, and hepatomegaly as compared to glucose-supplemented HFD mice, despite similar caloric intake. Fructose and glucose supplementation also had distinct effects on expression of the lipogenic transcription factors ChREBP and SREBP1c. While both sugars increased ChREBP-β, fructose supplementation uniquely increased SREBP1c and downstream fatty acid synthesis genes, resulting in reduced liver insulin signaling. In contrast, glucose enhanced total ChREBP expression and triglyceride synthesis but was associated with improved hepatic insulin signaling. Metabolomic and RNA sequence analysis confirmed dichotomous effects of fructose and glucose supplementation on liver metabolism in spite of inducing similar hepatic lipid accumulation. Ketohexokinase, the first enzyme of fructose metabolism, was increased in fructose-fed mice and in obese humans with steatohepatitis. Knockdown of ketohexokinase in liver improved hepatic steatosis and glucose tolerance in fructose-supplemented mice. Thus, fructose is a component of dietary sugar that is distinctively associated with poor metabolic outcomes, whereas increased glucose intake may be protective.

Vitamin D Status, Cardiometabolic, Liver, and Mental Health Status in Obese Youth Attending a Pediatric Weight Management Center

BACKGROUND

Vitamin D (VitD) deficiency and obesity are reaching epidemic proportions in North America, particularly in those with comorbid conditions such as diabetes or liver disease. The study objective was to determine the prevalence of suboptimal vitD status and interrelationships with anthropometric, cardiometabolic, liver, mental health, and lifestyle (sleep/screen time) parameters in an ambulatory population of children with obesity.

METHODS

Children (2-18 years) attending a pediatric weight management clinic (n = 217) were retrospectively reviewed. Variables studied included anthropometric (weight, height, body mass index, waist circumference), vitD (serum 25-hydroxyvitamin D), cardiometabolic (systolic blood pressure, diastolic blood pressure, glucose, insulin, homeostasis model assessment for insulin resistance, triglyceride, high-density lipoprotein, low-density lipoprotein, total cholesterol), liver enzymes (alanine aminotransferase, gamma-glutamyl transferase), and mental health (number, diagnosis) parameters.

RESULTS

Suboptimal vitD status (25-hydroxyvitamin D <75 nmol/L was present in 76% of children with obesity (12.0 ± 2.9 years). Blood pressure categorized as prehypertension, stage I hypertension, and stage II hypertension was present in 14%, 25%, and 7% of children, respectively. Mental health diagnoses including anxiety, attention-deficit hyperactivity disorder, mood disorders, and learning disabilities/developmental delays occurred in 18%, 17%, 10%, and 15%, of children, respectively. Waist circumferences >100 cm were associated with lower vitD levels (58 ± 18 vs 65 ± 17 nmol/L; P = 0.01). VitD status ≥50 nmol/L was associated with lower insulin (15.8 [11.7-23.1] mU/L vs 21.1 [14.3-34.2] mU/L; P < 0.01) and homeostasis model assessment for insulin resistance (3.5 [2.5-4.9] vs 4.8 [3.1-6.9]; P < 0.01) values and systolic blood pressure percentiles (73.0 ± 25.8 vs 80.6 ± 17.0; P = 0.04).

CONCLUSIONS

Children with obesity had a high prevalence of vitD deficiency, particularly those at risk for hypertension, reduced insulin sensitivity, and central obesity.

Effects of Dietary Fructose Restriction on Liver Fat, De Novo Lipogenesis, and Insulin Kinetics in Children With Obesity

BACKGROUND & AIMS

Consumption of sugar is associated with obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease, and cardiovascular disease. The conversion of fructose to fat in liver (de novo lipogenesis [DNL]) may be a modifiable pathogenetic pathway. We determined the effect of 9 days of isocaloric fructose restriction on DNL, liver fat, visceral fat (VAT), subcutaneous fat, and insulin kinetics in obese Latino and African American children with habitual high sugar consumption (fructose intake >50 g/d).

METHODS

Children (9-18 years old; n = 41) had all meals provided for 9 days with the same energy and macronutrient composition as their standard diet, but with starch substituted for sugar, yielding a final fructose content of 4% of total kilocalories. Metabolic assessments were performed before and after fructose restriction. Liver fat, VAT, and subcutaneous fat were determined by magnetic resonance spectroscopy and imaging. The fractional DNL area under the curve value was measured using stable isotope tracers and gas chromatography/mass spectrometry. Insulin kinetics were calculated from oral glucose tolerance tests. Paired analyses compared change from day 0 to day 10 within each child.

RESULTS

Compared with baseline, on day 10, liver fat decreased from a median of 7.2% (interquartile range [IQR], 2.5%-14.8%) to 3.8% (IQR, 1.7%-15.5%) (P < .001) and VAT decreased from 123 cm³ (IQR, 85-145 cm³) to 110 cm³ (IQR, 84-134 cm³) (P < .001). The DNL area under the curve decreased from 68% (IQR, 46%-83%) to 26% (IQR, 16%-37%) (P < .001). Insulin kinetics improved (P < .001). These changes occurred irrespective of baseline liver fat.

CONCLUSIONS

Short-term (9 days) isocaloric fructose restriction decreased liver fat, VAT, and DNL, and improved insulin kinetics in children with obesity. These findings support efforts to reduce sugar consumption. ClinicalTrials.gov Number: NCT01200043.

Diet quality of children post-liver transplantation does not differ from healthy children

Little has been studied regarding the diets of children following LTX. The study aim was to assess and compare dietary intake and DQ of healthy children and children post-LTX. Children and adolescents (2-18 years) post-LTX (n=27) and healthy children (n=28) were studied. Anthropometric and demographic data and two 24-hour recalls (one weekend; one weekday) were collected. Intake of added sugar, HFCS, fructose, GI, and GL was calculated. DQ was measured using three validated DQ indices: the HEI-C, the DGI-CA, and the DQI-I. Although no differences in weight-for-age z-scores were observed between groups, children post-LTX had lower height-for-age z-scores than healthy children (P<.01). With the exception of vitamin B12, no significant differences in energy and macronutrient (protein, carbohydrate, and fat), added sugar, HFCS, fructose, GI, GL, and micronutrient intakes and DQ indices (HEI-C, DGI-CA, and DQI-I) between groups were observed (P>.05). The majority of children in both groups (>40%) had low DQ scores. No significant interrelationships between dietary intake, anthropometric, and demographic were found (P>.05). Both healthy and children post-LTX consume diets with poor DQ. This has implications for risk of obesity and metabolic dysregulation, particularly in transplant populations on immunosuppressive therapies.

Role of Dietary Fructose and Hepatic De Novo Lipogenesis in Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a liver manifestation of metabolic syndrome. Overconsumption of high-fat diet (HFD) and increased intake of sugar-sweetened beverages are major risk factors for development of NAFLD. Today the most commonly consumed sugar is high fructose corn syrup. Hepatic lipids may be derived from dietary intake, esterification of plasma free fatty acids (FFA) or hepatic de novo lipogenesis (DNL). A central abnormality in NAFLD is enhanced DNL. Hepatic DNL is increased in individuals with NAFLD, while the contribution of dietary fat and plasma FFA to hepatic lipids is not significantly altered. The importance of DNL in NAFLD is further established in mouse studies with knockout of genes involved in this process. Dietary fructose increases levels of enzymes involved in DNL even more strongly than HFD. Several properties of fructose metabolism make it particularly lipogenic. Fructose is absorbed via portal vein and delivered to the liver in much higher concentrations as compared to other tissues. Fructose increases protein levels of all DNL enzymes during its conversion into triglycerides. Additionally, fructose supports lipogenesis in the setting of insulin resistance as fructose does not require insulin for its metabolism, and it directly stimulates SREBP1c, a major transcriptional regulator of DNL. Fructose also leads to ATP depletion and suppression of mitochondrial fatty acid oxidation, resulting in increased production of reactive oxygen species. Furthermore, fructose promotes ER stress and uric acid formation, additional insulin independent pathways leading to DNL. In summary, fructose metabolism supports DNL more strongly than HFD and hepatic DNL is a central abnormality in NAFLD. Disrupting fructose metabolism in the liver may provide a new therapeutic option for the treatment of NAFLD.

Sugar- and artificially sweetened beverages and intrahepatic fat: A randomized controlled trial

OBJECTIVE

To test the hypothesis that substituting artificially sweetened beverages (ASB) for sugar-sweetened beverages (SSB) decreases intrahepatocellular lipid concentrations (IHCL) in overweight subjects with high SSB consumption.

METHODS

About 31 healthy subjects with BMI greater than 25 kg/m(2) and a daily consumption of at least 660 ml SSB were randomized to a 12-week intervention in which they replaced SSBs with ASBs. Their IHCL (magnetic resonance spectroscopy), visceral adipose tissue volume (VAT; magnetic resonance imaging), food intake (2-day food records), and fasting blood concentrations of metabolic markers were measured after a 4-week run-in period and after a 12-week period with ASB or control (CTRL).

RESULTS

About 27 subjects completed the study. IHCL was reduced to 74% of the initial values with ASB (N = 14; P < 0.05) but did not change with CTRL. The decrease in IHCL attained with ASB was more important in subjects with IHCL greater than 60 mmol/l than in subjects with low IHCL. ALT decreased significantly with SSB only in subjects with IHCL greater than 60 mmol/l. There was otherwise no significant effect of ASB on body weight, VAT, or metabolic markers.

CONCLUSIONS

In subjects with overweight or obesity and a high SSB intake, replacing SSB with ASB decreased intrahepatic fat over a 12-week period.

Fructose and liver function--is this behind nonalcoholic liver disease?

PURPOSE OF REVIEW

The purpose was to summarize recent advances in the understanding of nonalcoholic fatty liver disease (NAFLD) pathophysiology and the role of fructose in NAFLD.

RECENT FINDINGS

Epidemiological studies continue to point to a strong association between high fructose intake and NAFLD and its severity. New studies of NAFLD reveal the importance of upregulated de novo lipogenesis as a key feature in its pathophysiology along with increased visceral adiposity and alteration of gut microbiome. Studies of fructose in NAFLD show how this nutrient may uniquely exacerbate the phenotype of NAFLD. The timing of exposure to fructose may be important with early (in utero) exposure being particularly harmful.

SUMMARY

Fructose is a potentially modifiable environmental exposure that appears to exacerbate NAFLD through multiple mechanisms. Although larger, longer clinical studies are still needed, it appears that limitation of fructose sources in the diet is beneficial in NAFLD.

Intensive lifestyle treatment for non-alcoholic fatty liver disease in children with severe obesity: inpatient versus ambulatory treatment

BACKGROUND/AIMS

Lifestyle intervention is the only established therapy for non-alcoholic fatty liver disease (NAFLD). The optimal treatment schedule and predictors of response of this treatment have not been established in children. We aimed to evaluate the 2-year efficacy of an inpatient versus ambulatory intensive lifestyle intervention for treating NAFLD in children with severe obesity.

METHODS

A cohort study of 51 severely obese non-diabetic children (mean age 14.7 (±2.4) years; BMI-z-score 3.5 (±0.5)) with liver steatosis were non-randomly allocated to inpatient treatment (2 or 6 months), ambulatory treatment or usual care. Proton Magnetic Resonance Spectroscopy determined liver steatosis and serum alanine aminotransferase (ALT) at 6 months were the primary outcome measures. Baseline variables were evaluated as predictors of treatment response.

RESULTS

Liver steatosis had disappeared in 43, 29 and 22% and serum ALT normalized in 41, 33 and 6% at the end of 6 months in the inpatient, ambulatory or usual care treatment groups, respectively. Only the proportions of ALT normalization in inpatient and ambulatory treatment compared with usual care were significantly higher. Treatment effects of inpatient and ambulatory treatment were sustained at 1.5 years follow-up. No baseline characteristic, including PNPLA3 polymorphism or leptin, was consistently predictive for treatment response.

CONCLUSIONS

A 6-month intensive inpatient and ambulatory lifestyle treatment in children with severe obesity reverses NAFLD in a minority of patients. This study suggests that inpatient compared with ambulatory intensive treatment does not importantly increase treatment success. Further efforts to optimize and individualize lifestyle interventions and additional treatments options are needed particular for children with severe obesity resistant to conventional lifestyle interventions.

Review article: the management of paediatric nonalcoholic fatty liver disease

BACKGROUND

Paediatric nonalcoholic fatty liver disease (NAFLD) is a major public health concern given the recent increase in its prevalence and link to obesity and other metabolic comorbidities. Current treatment strategies involve lifestyle changes. Other surgical and pharmacologic interventions have been proposed; however, limited randomised controlled trials (RCTs) in the paediatric population restrict their use.

AIM

To review the current management of paediatric NAFLD, including lifestyle and pharmacologic interventions, and to formulate recommendations for study design for future studies.

METHODS

A MEDLINE, Pubmed and Cochrane Review database search used a combination of keywords, including NAFLD, nonalcoholic steatohepatitis (NASH), paediatric, treatments, lifestyle changes, bariatric surgery, orlistat, metformin, thiazolidinediones, vitamin E, cysteamine bitartrate, ursodeoxycholic acid (UDCA), probiotics, omega-3 fatty acids, pentoxyfylline, farnesoid X receptor agonist and toll-like receptor modifiers. The articles were selected based on their relevance to the review.

RESULTS

Lifestyle interventions involving diet and exercise remain first-line treatment for paediatric NAFLD. Bariatric surgery, orlistat, insulin sensitisers and UDCA have been evaluated but are not recommended as first or second-line therapy. Medications such as cysteamine bitartrate, probiotics, polyunsaturated fats and pentoxyfilline share beneficial effects in trials, however, there is a paucity of adequately powered RCTs in which liver histology is evaluated. Vitamin E has been shown to be effective and safe in improving NASH histology in children.

CONCLUSIONS

Lifestyle intervention should be first-line treatment for paediatric NAFLD. Vitamin E should be considered for those with biopsy-proven NASH or borderline NASH failing first-line therapy. Other therapeutics show promising results but require larger RCTs with convincing endpoints. Improved screening techniques, objective validated inclusion criteria and outcome measures as well as rigour in study design are necessary for propelling therapeutic discovery.

Characterizing severe obesity in children and youth referred for weight management

Background

Severe obesity (SO) in pediatrics has become increasing prevalent in recent decades.

The objective of our study was to examine differences in demographic, anthropometric, cardiometabolic, and lifestyle variables in children and youth with SO versus their less overweight/obese (OW/OB) peers.

Methods

A retrospective medical record review of 6-19 year old participants enrolled in an outpatient pediatric weight management clinic was conducted. SO (body mass index [BMI] ≥99^th percentile) and OW/OB (BMI ≥85^th and <99^th percentile) groups were created according to Centers for Disease Control and Prevention definitions. Demographic, anthropometric, cardiometabolic and lifestyle data reported at baseline (pre-intervention) were retrieved.

Results

Of the 345 participants, most were girls (56.2%), Caucasian (78.7%), and had family incomes > $50,000/year (65.7%). The SO group (n = 161) had lower HDL-cholesterol and higher liver enzymes, insulin resistance and blood pressure than the OW/OB group (n = 184; all p < 0.01). They also reported higher total energy intakes, fewer steps/day, less moderate-to-vigorous physical activity, and more leisure time screen time (all p < 0.02) than their leaner peers. Compared to the OW/OB group, a higher proportion of individuals in the SO group possessed cardiometabolic risk factors, including high triglycerides (45.8% vs 58.5%), alanine aminotransferase (55.4% vs 81.4%), insulin resistance (55.6% vs 82.1%), systolic blood pressure (11.5% vs 27.3%), diastolic blood pressure (17.8% vs 30.0%), and low HDL-cholesterol (44.6% vs 64.6%; all p < 0.02). Aside from the ~75% of participants (groups combined) who met the daily recommended intakes of grain and meat products, <50% of boys and girls met any of the remaining nutrition and physical activity-related recommendations. Compared to the OW/OB group, greater proportions of children and youth in the SO group failed to meet moderate-to-vigorous physical activity (48.4% vs 31.9%) and leisure-time-screen-time recommendations (43.4% vs 28.3%; both p < 0.05).

Conclusion

Children and youth with SO have a worse cardiometabolic profile and less favorable lifestyle habits than their OW/OB peers. These differences emphasize the heightened obesity-related health risks associated with SO in the pediatric years.

Parental perceptions regarding lifestyle interventions for obese children and adolescents with nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) affects 30% of obese children globally. The main treatment for NAFLD is to promote gradual weight loss through lifestyle modification. Very little is known regarding parental perspectives about the barriers and facilitators that influence the ability to promote healthy lifestyle behaviours in children with NAFLD.

OBJECTIVES

To explore and describe parental perspectives regarding barriers to and facilitators of implementing lifestyle modification in children with NAFLD.

METHODS

A mixed-methods approach, including qualitative methodology (focus groups) and validated questionnaires (Lifestyle Behaviour Checklist), was used to assess parental perceptions regarding barriers to and facilitators of lifestyle change in parents of children with healthy body weights (control parents) and in parents of children with NAFLD (NAFLD parents).

RESULTS

NAFLD parents identified more problem behaviours related to food portion size and time spent in nonsedentary physical activity, and lower parental self-efficacy than parents of controls (P<0.05). Major barriers to lifestyle change cited by NAFLD parents were lack of time, self-motivation and role modelling of healthy lifestyle behaviours. In contrast, control parents used a variety of strategies to elicit healthy lifestyle behaviours in their children including positive role modelling, and inclusion of the child in food preparation and meal purchasing decisions, and perceived few barriers to promoting healthy lifestyles. Internet sources were the main form of nutrition information used by parents.

CONCLUSIONS

Lifestyle modification strategies focused on promoting increased parental self-efficacy and parental motivation to promote healthy lifestyle behaviour are important components in the treatment of obese children with NAFLD.

Nutrition, nonalcoholic fatty liver disease and the microbiome: recent progress in the field

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and it has overlapping pathogenesis with diabetes and cardiovascular disease. Reviewed here are recent advances in understanding the contribution of diet and selected nutrients to NAFLD.

RECENT FINDINGS

To understand the effect of diet, the microbiome must be considered because it is the interface of diet and the liver. Early studies suggest that the characteristic of the microbiota is altered in NAFLD. Fructose is a lipogenic carbohydrate that contributes to insulin resistance, hypertriglyceridemia and appears to be associated with the severity of NAFLD. Fructose absorption and malabsorption may alter the microbiota and could be mediating effects on the liver. Lipids also have potent microbiome interactions and could contribute to the benefit of diets emphasizing lipid changes. Several new studies demonstrate that the Mediterranean diet and 'lifestyle change' are effective in modestly improving NAFLD. A new study of 'lifestyle' in children showed simultaneous improvement in cardiovascular disease risk measurements and hepatic steatosis.

SUMMARY

Current data supports limiting sugar in the diet and 'lifestyle change' as a first-line treatment for NAFLD; however, the benefits from these appear to be modest. The effects of diet on the liver are mediated through the microbiome and expansion of research in this area is needed.