Are saturated fatty acids and insulin resistance associated with fatty liver in obese children?

Associations of diet quality and food consumption with serum biomarkers for lipid and amino acid metabolism in Finnish children: the PANIC study

PURPOSE

To investigate the associations of overall diet quality and dietary factors with serum biomarkers for lipid and amino acid metabolism in a general population of children.

METHODS

We studied 194 girls and 209 boys aged 6-8 years participating in the Physical Activity and Nutrition in Children study. Food consumption was assessed by 4-day food records and diet quality was quantified by the Finnish Children Healthy Eating Index (FCHEI). Fasting serum fatty acids, amino acids, apolipoproteins, as well as lipoprotein particle sizes were analyzed with high-throughput nuclear magnetic resonance spectroscopy. Data were analyzed using linear regression adjusted for age, sex, and body fat percentage.

RESULTS

FCHEI was directly associated with the ratio of polyunsaturated (PUFA) to saturated fatty acids (SFA) (PUFA/SFA), the ratio of PUFA to monounsaturated fatty acids (MUFA) (PUFA/MUFA), the ratio of PUFA to total fatty acids (FA) (PUFA%), the ratio of omega-3-fatty acids to total FA (omega-3 FA%), and inversely associated with the ratio of MUFA to total FA (MUFA%), alanine, glycine, histidine and very-low density lipoprotein (VLDL) particle size. Consumption of vegetable oils and vegetable-oil-based margarine (≥ 60% fat) was directly associated with PUFA/SFA, PUFA/MUFA, PUFA%, the ratio of omega-6 FA to total FA (omega-6 FA%), and inversely associated with SFA, MUFA, SFA to total FA (SFA%), MUFA%, alanine and VLDL particle size. Consumption of high-fiber grain products directly associated with PUFA/SFA, PUFA/MUFA, omega-3 FA%, omega-6 FA%, PUFA% and inversely associated with SFA and SFA%. Fish consumption directly related to omega-3 FA and omega-3 FA%. Consumption of sugary products was directly associated with histidine and VLDL particle size. Vegetable, fruit, and berry consumption had direct associations with VLDL particle size and the ratio of apolipoprotein B to apolipoprotein A1. Consumption of low fat (< 1%) milk was directly associated with phenylalanine. A higher consumption of high-fat (≥ 1%) milk was associated with lower serum MUFA/SFA and higher SFA%. Sausage consumption was directly related to SFA% and histidine. Red meat consumption was inversely associated with glycine.

CONCLUSIONS

Better diet quality, higher in intake of dietary sources of unsaturated fat and fiber, and lower in sugary product intake were associated with more favorable levels of serum biomarkers for lipid and amino acid metabolism independent of adiposity.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01803776, registered March 3, 2013.

Dietary fat composition shapes bile acid metabolism and severity of liver injury in a pig model of pediatric NAFLD

The objective of this study was to investigate the effect of dietary fatty acid (FA) composition on bile acid (BA) metabolism in a pig model of NAFLD, by using a multiomics approach combined with histology and serum biochemistry. Thirty 20-day-old Iberian pigs pair-housed in pens were randomly assigned to receive 1 of 3 hypercaloric diets for 10 wk: 1) lard-enriched (LAR; n = 5 pens), 2) olive oil-enriched (OLI; n = 5), and 3) coconut oil-enriched (COC; n = 5). Animals were euthanized on week 10 after blood sampling, and liver, colon, and distal ileum (DI) were collected for histology, metabolomics, and transcriptomics. Data were analyzed by multivariate and univariate statistics. Compared with OLI and LAR, COC increased primary and secondary BAs in liver, plasma, and colon. In addition, both COC and OLI reduced circulating fibroblast growth factor 19, increased hepatic necrosis, composite lesion score, and liver enzymes in serum, and upregulated genes involved in hepatocyte proliferation and DNA repair. The severity of liver disease in COC and OLI pigs was associated with increased levels of phosphatidylcholines, medium-chain triacylglycerides, trimethylamine-N-oxide, and long-chain acylcarnitines in the liver, and the expression of profibrotic markers in DI, but not with changes in the composition or size of BA pool. In conclusion, our results indicate a role of dietary FAs in the regulation of BA metabolism and progression of NAFLD. Interventions that aim to modify the composition of dietary FAs, rather than to regulate BA metabolism or signaling, may be more effective in the treatment of NAFLD.NEW & NOTEWORTHY Bile acid homeostasis and signaling is disrupted in NAFLD and may play a central role in the development of the disease. However, there are no studies addressing the impact of diet on bile acid metabolism in patients with NAFLD. In juvenile Iberian pigs, we show that fatty acid composition in high-fat high-fructose diets affects BA levels in liver, plasma, and colon but these changes were not associated with the severity of the disease.

Associations of Nutrient Intake Changes During Childhood with Adolescent Hepatic Fat: The Exploring Perinatal Outcomes Among CHildren Study

OBJECTIVE

To examine associations of dietary changes from childhood to adolescence with adolescent hepatic fat and whether the PNPLA3 rs738409 risk allele, a strong genetic risk factor for hepatic fat, modifies associations.

STUDY DESIGN

Data were from 358 participants in the Exploring Perinatal Outcomes among CHildren (EPOCH) study, a longitudinal cohort in Colorado. Diet was assessed by food frequency questionnaire in childhood (approximately 10 years of age) and adolescence (approximately 16 years of age) and converted to nutrient densities. Hepatic fat was assessed in adolescence by magnetic resonance imaging. Linear regression was used to test associations of dietary changes from childhood to adolescence with adolescent hepatic fat.

RESULTS

Increases in fiber, vegetable protein, and polyunsaturated fat intake from childhood to adolescence were associated with lower adolescent hepatic fat, and increases in animal protein were associated with higher hepatic fat (β per 5-unit increase on log-hepatic fat: -0.12 [95% CI, -0.21 to -0.02] for ▵fiber; -0.26 [95% CI, -0.45 to -0.07] for ▵vegetable protein; -0.18 [95% CI, -0.35 to -0.02] for ▵polyunsaturated fat; 0.13 [95% CI, 0.04-0.22] for ▵animal protein). There was evidence of effect modification by PNPLA3 variant, whereby inverse associations of ▵fiber and ▵vegetable protein and positive associations of ▵saturated fat with adolescent hepatic fat were stronger in risk allele carriers. Most conclusions were similar after adjusting for obesity in adolescence, but associations of ▵saturated fat with hepatic fat were attenuated toward the null.

CONCLUSIONS

Our results suggest that nutrient intake changes between childhood and adolescence, particularly decreases in fiber and vegetable protein and increases in saturated fat intake, interact with the PNPLA3 variant to predict higher hepatic fat in adolescence, and may be targets for reducing hepatic fat in high-risk youth.

The relation of saturated fatty acids with low-grade inflammation and cardiovascular disease

The mantra that dietary (saturated) fat must be minimized to reduce cardiovascular disease (CVD) risk has dominated nutritional guidelines for decades. Parallel to decreasing intakes of fat and saturated fatty acids (SFA), there have been increases in carbohydrate and sugar intakes, overweight, obesity and type 2 diabetes mellitus. The "lipid hypothesis" coined the concept that fat, especially SFA, raises blood low-density lipoprotein-cholesterol and thereby CVD risk. In view of current controversies regarding their adequate intakes and effects, this review aims to summarize research regarding this heterogenic group of fatty acids and the mechanisms relating them to (chronic) systemic low-grade inflammation, insulin resistance, metabolic syndrome and notably CVD. The intimate relationship between inflammation and metabolism, including glucose, fat and cholesterol metabolism, revealed that the dyslipidemia in Western societies, notably increased triglycerides, "small dense" low-density lipoprotein and "dysfunctional" high-density lipoprotein, is influenced by many unfavorable lifestyle factors. Dietary SFA is only one of these, not necessarily the most important, in healthy, insulin-sensitive people. The environment provides us not only with many other proinflammatory stimuli than SFA but also with many antiinflammatory counterparts. Resolution of the conflict between our self-designed environment and ancient genome may rather rely on returning to the proinflammatory/antiinflammatory balance of the Paleolithic era in consonance with the 21st century culture. Accordingly, dietary guidelines might reconsider recommendations for SFA replacement and investigate diet in a broader context, together with nondietary lifestyle factors. This should be a clear priority, opposed to the reductionist approach of studying the effects of single nutrients, such as SFA.

Childhood energy intake is associated with nonalcoholic fatty liver disease in adolescents

BACKGROUND

Greater adiposity is an important risk factor for nonalcoholic fatty liver disease (NAFLD). Thus, it is likely that dietary intake is involved in the development of the disease. Prospective studies assessing the relation between childhood dietary intake and risk of NAFLD are lacking.

OBJECTIVE

This study was designed to explore associations between energy, carbohydrate, sugar, starch, protein, monounsaturated fat, polyunsaturated fat, saturated fat, and total fat intake by youth at ages 3, 7, and 13 y and subsequent (mean age: 17.8 y) ultrasound scan (USS)-measured liver fat and stiffness and serum alanine aminotransferase, aspartate aminotransferase, and γ-glutamyltransferase. We assessed whether observed associations were mediated through fat mass at the time of outcome assessment.

METHODS

Participants were from the Avon Longitudinal Study of Parents and Children. Trajectories of energy and macronutrient intake from ages 3-13 y were obtained with linear-spline multilevel models. Linear and logistic regression models examined whether energy intake and absolute and energy-adjusted macronutrient intake at ages 3, 7, and 13 y were associated with liver outcomes.

RESULTS

Energy intake at all ages was positively associated with liver outcomes; for example, the odds of having a USS-measured liver fat per 100 kcal increase in energy intake at age 3 y were 1.79 (95% CI: 1.14, 2.79). Associations between absolute macronutrient intake and liver outcomes were inconsistent and attenuated to the null after adjustment for total energy intake. The majority of associations attenuated to the null after adjustment for fat mass at the time liver outcomes were assessed.

CONCLUSION

Higher childhood and early adolescent energy intake is associated with greater NAFLD risk, and the macronutrients from which energy intake is derived are less important. These associations appear to be mediated, at least in part, by fat mass at the time of outcome assessment.

Paediatric non-alcoholic fatty liver disease: an overview

Non-alcoholic fatty liver disease (NAFLD) is a progressive disease that encompasses a spectrum of liver diseases, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Data related to survival in children are scarce, but these data firmly associate NAFLD with higher risks of hepatic and non-hepatic morbidities and mortalities compared with the general population. More recently, the association between NAFLD and cardiovascular disease among children has increasingly been recognized. Given that obesity is a major risk factor for the disease, paediatric NAFLD is becoming a global issue, paralleling the dramatic rise in obesity worldwide. NASH, which is more common in obese children, has the potential to advance to liver fibrosis and failure. It is unclear why certain patients undergo such transformation but this susceptibility is likely related to an interaction between a genetically susceptible host and the surrounding environment. Currently, treatment is largely conservative and includes lifestyle modification, attainable through healthy weight reduction via diet and exercise. In this review, current knowledge about NAFLD in children is summarized. This review aims to increase the awareness of the medical community about a hidden public health issue and to identify current gaps in the literature while providing directions for future research.

Dietary determinants of hepatic steatosis and visceral adiposity in overweight and obese youth at risk of type 2 diabetes

BACKGROUND

Dietary determinants of hepatic steatosis, an important precursor for nonalcoholic fatty liver disease, are undefined.

OBJECTIVE

We explored the roles of sugar and fat intake as determinants of hepatic steatosis and visceral obesity in overweight adolescents at risk of type 2 diabetes.

DESIGN

This was a cross-sectional study of dietary patterns and adipose tissue distribution in 74 overweight adolescents (aged: 15.4 ± 1.8 y; body mass index z score: 2.2 ± 0.4). Main outcome measures were hepatic steatosis (≥5.5% fat:water) measured by magnetic resonance spectroscopy and visceral obesity (visceral-to-subcutaneous adipose tissue ratio ≥0.25) measured by magnetic resonance imaging. Main exposure variables were dietary intake and habits assessed by the Harvard Youth Adolescent Food Frequency Questionnaire.

RESULTS

Hepatic steatosis and visceral obesity were evident in 43% and 44% of the sample, respectively. Fried food consumption was more common in adolescents with hepatic steatosis than in adolescents without hepatic steatosis (41% compared with 18%; P = 0.04). Total fat intake (β = 0.51, P = 0.03) and the consumption of >35% of daily energy intake from fat (OR: 11.8; 95% CI: 1.6, 86.6; P = 0.02) were both positively associated with hepatic steatosis. Available carbohydrate (β = 0.54, P = 0.02) and the frequent consumption of soda were positively associated with visceral obesity (OR: 6.4; 95% CI: 1.2, 34.0; P = 0.03). Daily fiber intake was associated with reduced odds of visceral obesity (OR: 0.82; 95% CI: 0.68, 0.98; P = 0.02) but not hepatic steatosis.

CONCLUSION

Hepatic steatosis is associated with a greater intake of fat and fried foods, whereas visceral obesity is associated with increased consumption of sugar and reduced consumption of fiber in overweight and obese adolescents at risk of type 2 diabetes.

Lipotoxicity: effects of dietary saturated and transfatty acids

The ingestion of excessive amounts of saturated fatty acids (SFAs) and transfatty acids (TFAs) is considered to be a risk factor for cardiovascular diseases, insulin resistance, dyslipidemia, and obesity. The focus of this paper was to elucidate the influence of dietary SFA and TFA intake on the promotion of lipotoxicity to the liver and cardiovascular, endothelial, and gut microbiota systems, as well as on insulin resistance and endoplasmic reticulum stress. The saturated and transfatty acids favor a proinflammatory state leading to insulin resistance. These fatty acids can be involved in several inflammatory pathways, contributing to disease progression in chronic inflammation, autoimmunity, allergy, cancer, atherosclerosis, hypertension, and heart hypertrophy as well as other metabolic and degenerative diseases. As a consequence, lipotoxicity may occur in several target organs by direct effects, represented by inflammation pathways, and through indirect effects, including an important alteration in the gut microbiota associated with endotoxemia. Interactions between these pathways may perpetuate a feedback process that exacerbates an inflammatory state. The importance of lifestyle modification, including an improved diet, is recommended as a strategy for treatment of these diseases.

The effects of dietary weight loss with or without exercise training on liver enzymes in obese metabolic syndrome subjects

AIM

Insulin resistance and visceral adiposity are predisposing factors for fatty liver disease. The main objectives of this study were (i) to compare the effects of caloric restriction (CR) alone or together with moderate-intensity aerobic exercise training (CR+EX) on liver enzymes, a surrogate marker of liver injury, in obese metabolic syndrome (MetS) subjects and (ii) to identify anthropometric, metabolic, cardiovascular and dietary predictors of changes in liver enzymes.

METHODS

Sedentary men and women (n = 63), aged 55 ± 6 (s.d.) years with body mass index 32.7 ± 4.1 kg/m(2) and confirmed MetS, were randomized to 12-week CR, CR+EX or no treatment (Control).

RESULTS

Weight loss averaged 7.6% in the CR and 9.1% in the CR+EX group (time effect, p < 0.001; group effect, p = 0.11); insulin sensitivity improved by 49 and 45%, respectively (both p < 0.001). Fitness (maximal oxygen consumption) increased by 19% in the CR+EX group only (p < 0.001). Alanine aminotransferase (ALT) levels decreased by 20% in the CR and 24% in the CR+EX group (time effect, both p < 0.001; group effect, p = 0.68); corresponding values for γ-glutamyltransferase (GGT) were -28 and -33%, respectively (time effect, both p < 0.001; group effect, p = 0.28). Reduction in abdominal fat mass (measured by DXA from L1 to L4) independently predicted ΔALT (r = 0.42, p = 0.005) and ΔGGT (r = 0.55, p < 0.001), whereas change in dietary saturated fat intake was independently associated with ΔALT (r = 0.35, p = 0.03).

CONCLUSIONS

Reductions in central adiposity and saturated fat intake are key drivers of improvement in liver enzymes during lifestyle interventions. Exercise training did not confer significant incremental benefits in this study.

Metabolic predictors for early identification of fatty liver using doppler and B-mode ultrasonography in overweight and obese adolescents

(1) to evaluate the frequency of asymptomatic fatty liver disease (FLD) using both Doppler and B-mode ultrasound (US) in overweight and obese adolescents; (2) to compare metabolic findings of fatty liver (FL) assessed by two methods; and (3) to evaluate metabolic predictors of FL shown by these methods. Fifty-nine overweight and obese adolescents aged between 9.0 and 17.0 years and 41 non-obese healthy adolescents were included in this study. B-mode and right hepatic vein Doppler ultrasonography (US) were performed and anthropometric indices, lipid profiles, and adiponectin levels were evaluated in all adolescents. HDL-C levels were significantly lower in patients with FL detected by Doppler US compared to patients without FL (p < 0.05). HDL-C levels were inversely correlated with presence of FL assessed by two methods (r = -0.285, p = 0.004; r = -0.328, p = 0.001, respectively) and adiponectin levels were correlated with presence of FL only detected by B-mode US (r = -0.263, p = 0.008). Adiponectin levels were significantly lower in patients with FL than those without FL assessed by B-Mode US (p = 0.049). Multiple regression analysis revealed that HDL-C levels was the most important predictor of FL assessed by Doppler US (p = 0.027), while body mass index was the determinant of FL assessed by two methods (p < 0.001) in asymptomatic overweight and obese adolescents. It was found that FLD, identified by both B-mode and Doppler US, is seen frequently in asymptomatic overweight and obese adolescents. Elevated BMI is associated with increased risk of FL assessed by two ultrasonographic methods. When using Doppler US, low HDL-C levels can be used as a good predictor for presence of FLD in overweight and obese adolescents.

The role of nutritional profile in the orexigenic neuropeptide secretion in nonalcoholic fatty liver disease obese adolescents

BACKGROUND

Little progress has been made to identify the central neuroendocrine pathway involved in the energy intake control in nonalcoholic fatty liver disease (NAFLD) patients.

OBJECTIVE

To assess the influence of orexigenic neuropeptides in the nutritional aspects of NAFLD obese adolescents submitted to a long-term interdisciplinary approach.

METHODS

Fifty adolescents aged 15-19 years, with body mass index at least 95th percentile, consisting of 25 patients without NAFLD and 25 with NAFLD. The NAFLD diagnosis was determined by ultrasonography. Blood samples were collected to analyze glycemia, hepatic transaminases, and lipid profile. Insulin resistance was estimated by Homeostasis Model Assessment Insulin Resistance Index. Neuropeptide Y (NPY) and agouti related protein concentrations were measured by enzyme-linked immunosorbent assay. Analyses of food intake were made by 3 days recordatory inquiry.

RESULTS

At baseline conditions, the patients with NAFLD had significantly higher values of body mass, body mass index, visceral fat, triglycerides, VLDL-C, and hepatic transaminases. After the long-term intervention, they presented a significant reduction in these parameters. In both the groups, it was observed a significant decrease in energy intake, macronutrients and dietetic cholesterol. Only the patients with NAFLD presented a positive correlation between the saturated fatty acids intake and the orexigenic neuropeptides NPY and agouti related protein, and carbohydrate with NPY. Indeed, it was observed a positive correlation between energy intake, lipid (%) and saturated fatty acids with visceral fat accumulation.

CONCLUSION

Our findings showed an important influence of diet composition in the orexigenic system, being essential consider that the excessive saturated fatty acids intake could be a determinant factor to increase nonalcoholic fatty liver disease.