Concentrations of Plasma Free Palmitoleic and Dihomo-Gamma Linoleic Fatty Acids Are Higher in Children with Abdominal Obesity

Protocol for a randomized placebo-controlled clinical trial using pure palmitoleic acid to ameliorate insulin resistance and lipogenesis in overweight and obese subjects with prediabetes

Palmitoleic acid (POA), a nonessential, monounsaturated omega-7 fatty acid (C16:1n7), is a lipid hormone secreted from adipose tissue and has beneficial effects on distant organs, such as the liver and muscle. Interestingly, POA decreases lipogenesis in toxic storage sites such as the liver and muscle, and paradoxically increases lipogenesis in safe storage sites, such as adipose tissue. Furthermore, higher POA levels in humans are correlated with better insulin sensitivity, an improved lipid profile, and a lower incidence of type-2 diabetes and cardiovascular pathologies, such as myocardial infarction. In preclinical animal models, POA improves glucose intolerance, dyslipidemia, and steatosis of the muscle and liver, while improving insulin sensitivity and secretion. This double-blind placebo-controlled clinical trial tests the hypothesis that POA increases insulin sensitivity and decreases hepatic lipogenesis in overweight and obese adult subjects with pre-diabetes. Important to note, that this is the first study ever to use pure (>90%) POA with < 0.3% palmitic acid (PA), which masks the beneficial effects of POA. The possible positive findings may offer a therapeutic and/or preventative pathway against diabetes and related immunometabolic diseases.

Impaired Reverse Cholesterol Transport is Associated with Changes in Fatty Acid Profile in Children and Adolescents with Abdominal Obesity

BACKGROUND

Abdominal obesity is an important cardiovascular disease risk factor. Plasma fatty acids display a complex network of both pro and antiatherogenic effects. High density lipoproteins (HDL) carry out the antiatherogenic pathway called reverse cholesterol transport (RCT), which involves cellular cholesterol efflux (CCE), and lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) activities.

OBJECTIVES

Our aim was to characterize RCT and its relation to fatty acids present in plasma in pediatric abdominal obesity.

METHODS

Seventeen children and adolescents with abdominal obesity and 17 healthy controls were studied. Anthropometric parameters were registered. Glucose, insulin, lipid levels, CCE employing THP-1 cells, LCAT and CETP activities, plus fatty acids in apo B-depleted plasma were measured.

RESULTS

The obese group showed a more atherogenic lipid profile, plus lower CCE (Mean±Standard Deviation) (6 ± 2 vs. 7 ± 2%; P < 0.05) and LCAT activity (11 ± 3 vs. 15 ±5 umol/dL.h; P < 0.05). With respect to fatty acids, the obese group showed higher myristic (1.1 ± 0.3 vs. 0.7 ± 0.3; P < 0.01) and palmitic acids (21.5 ± 2.8 vs. 19.6 ± 1.9; P < 0.05) in addition to lower linoleic acid (26.4 ± 3.3 vs. 29.9 ± 2.6; P < 0.01). Arachidonic acid correlated with CCE (r = 0.37; P < 0.05), myristic acid with LCAT (r = -0.37; P < 0.05), palmitioleic acid with CCE (r = -0.35; P < 0.05), linoleic acid with CCE (r = 0.37; P < 0.05), lauric acid with LCAT (r = 0.49; P < 0.05), myristic acid with LCAT (r = -0.37; P < 0.05) ecoisatrienoic acid with CCE (r = 0.40; P < 0.05) and lignoseric acid with LCAT (r = -0.5; P < 0.01).

CONCLUSIONS

Children and adolescents with abdominal obesity presented impaired RCT, which was associated with modifications in proinflammatory fatty acids, such as palmitoleic and myristic, thus contributing to increased cardiovascular disease risk.

Correlation of body mass index and waist to height ratio with cardiovascular risk factors in Colombian preschool and school children

Objective

To analyze the agreement between body mass index (BMI) and waist-to-height Ratio (WHtR) to identify preschool and school children with cardiovascular risk factors (CRFs).

Methods

Three-hundred-twenty-one kids were divided into preschool (3-5 years) and school children (6-10 years). BMI was used to classify children as overweight or obese. Abdominal obesity was defined with a WHtR ≥0.50. Fasting blood lipids, glucose and insulin were measured, and the homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. The presence of CRFs and multiple non-waist circumference (non-WC) metabolic syndrome factors (MetS-Factors) [high HOMA-IR, high triglycerides and low high-density lipoprotein cholesterol (HDL-C)] were analyzed.

Results

One-hundred-twelve preschool and 209 school children were evaluated. WHtR ≥0.50 classified abdominal obesity in more than half of the preschool children, exceeding those classified with overweight+obesity by BMI (59.5% vs. 9.8%; p<0.001). There was no agreement between WHtR and BMI to identify preschool kids with CRFs and multiple non-WC MetS-Factors (kappa: 0.0 to 0.23, p>0.05). There were similar proportions of school children classified with abdominal obesity by the WHtR and overweight+obesity by the BMI (18.7% vs. 24.9%; p>0.05). There was substantial agreement between WHtR and BMI to identify school children with high total cholesterol values, low-density lipoprotein cholesterol (LDL-C), triglycerides, non-HDL-C, insulin, HOMA-IR, low HDL-C values, and the presence of multiple non-WC MetS-Factors (kappa: 0.616 to 0.857, p<0.001).

Conclusion

In preschool children WHtR ≥0.5 disagree with BMI results, but in school kids, it has good agreement with the BMI to classify the children´s nutritional status and to identify those with CRFs.

Paediatric obesity: a systematic review and pathway mapping of metabolic alterations underlying early disease processes

BACKGROUND

The alarming trend of paediatric obesity deserves our greatest awareness to hinder the early onset of metabolic complications impacting growth and functionality. Presently, insight into molecular mechanisms of childhood obesity and associated metabolic comorbidities is limited. This systematic review aimed at scrutinising what has been reported on putative metabolites distinctive for metabolic abnormalities manifesting at young age by searching three literature databases (Web of Science, Pubmed and EMBASE) during the last 6 years (January 2015-January 2021). Global metabolomic profiling of paediatric obesity was performed (multiple biological matrices: blood, urine, saliva and adipose tissue) to enable overarching pathway analysis and network mapping. Among 2792 screened Q1 articles, 40 met the eligibility criteria and were included to build a database on metabolite markers involved in the spectrum of childhood obesity. Differential alterations in multiple pathways linked to lipid, carbohydrate and amino acid metabolisms were observed. High levels of lactate, pyruvate, alanine and acetate marked a pronounced shift towards hypoxic conditions in children with obesity, and, together with distinct alterations in lipid metabolism, pointed towards dysbiosis and immunometabolism occurring early in life. Additionally, aberrant levels of several amino acids, most notably belonging to tryptophan metabolism including the kynurenine pathway and its relation to histidine, phenylalanine and purine metabolism were displayed. Moreover, branched-chain amino acids were linked to lipid, carbohydrate, amino acid and microbial metabolism, inferring a key role in obesity-associated insulin resistance.

CONCLUSIONS

This systematic review revealed that the main metabolites at the crossroad of dysregulated metabolic pathways underlying childhood obesity could be tracked down to one central disturbance, i.e. impending insulin resistance for which reference values and standardised measures still are lacking. In essence, glycolytic metabolism was evinced as driving energy source, coupled to impaired Krebs cycle flux and ß-oxidation. Applying metabolomics enabled to retrieve distinct metabolite alterations in childhood obesity(-related insulin resistance) and associated pathways at early age and thus could provide a timely indication of risk by elucidating early-stage biomarkers as hallmarks of future metabolically unhealthy phenotypes.

Palmitoleic and Dihomo-γ-Linolenic Acids Are Positively Associated With Abdominal Obesity and Increased Metabolic Risk in Children

Background: The impact of abdominal obesity (AO) on plasma fatty acid changes and cardiometabolic risk in children who are obese and overweight has rarely been investigated. This study determined whether plasma fatty acid composition differed between children with AO and those without AO and its relationship with metabolic risk, particularly in the obese and overweight groups. Methods: A total of 181 schoolchildren (aged 7-18 years) were included. Anthropometric and biochemical data and plasma fatty acid profiles were analyzed, and the indices of desaturase activity were estimated. Children were categorized based on their body weight and AO status. A continuous metabolic risk score was calculated using the sum of the z-scores of metabolic variables. A one-way analysis of variance test was used to compare the composition ratio of fatty acids between children with and without AO in the obese and overweight groups and normal-weight controls. Pearson analysis was also used to explore significant fatty acid and desaturase indicators associated with metabolic abnormalities. Results: Children who were obese and overweight (N = 126) displayed higher dihomo-γ-linolenic acid (20:3n-6) and γ-linolenic acid (18:3n-6) proportions than normal-weight controls (N = 55), but lower heptadecanoic acid (17:0) proportion, regardless of the AO status of each individual. Obese and overweight children with AO (N = 89), but not their non-AO counterparts (N = 37), exhibited a significantly higher proportion of palmitoleic acid (16:1n-7) than the remaining study groups. Pearson analysis showed that high proportions of palmitoleic acid and dihomo-γ-linolenic acid, as well as increased stearoyl-coenzyme A desaturase-1(16) and delta-6 desaturase and decreased delta-5 desaturase activities, are strongly correlated with weight-height ratio, homeostasis model of assessment values for insulin resistance, hypertriglyceridemia, and continuous metabolic risk scores. Conclusion: Higher palmitoleic acid and dihomo-γ-linolenic acid proportions, as well as increased stearoyl-coenzyme A desaturase-1(16) and delta-6 desaturase and decreased delta-5 desaturase activities are associated with AO and increased metabolic risk in children who are obese and overweight.

Regulation of the cytochrome P450 epoxyeicosanoid pathway is associated with distinct histologic features in pediatric non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a significant health burden in obese children for which there is currently no specific therapy. Preclinical studies indicate that epoxyeicosanoids, a class of bioactive lipid mediators that are generated by cytochrome P450 (CYP) epoxygenases and inactivated by the soluble epoxide hydrolase (sEH), play a protective role in NAFLD. We performed a comprehensive lipidomics analysis using liver tissue and blood samples of 40 children with NAFLD. Proteomics was performed to determine CYP epoxygenase and sEH expressions. Hepatic epoxyeicosanoids significantly increased with higher grades of steatosis, while their precursor PUFAs were unaltered. Concomitantly, total CYP epoxygenase activity increased while protein level and activity of sEH decreased. In contrast, hepatic epoxyeicosanoids showed a strong decreasing trend with higher stages of fibrosis, accompanied by a decrease of CYP epoxygenase activity and protein expression. These findings suggest that the CYP epoxygenase/sEH pathway represents a potential pharmacologic target for the treatment of NAFLD.

Selective and fast methylation of free fatty acids directly in plasma for their individual analysis by gas chromatography- mass spectrometry

An analytical procedure for the rapid and selective derivatization of free fatty acids into methyl esters directly in plasma without transmethylation of lipid-bound fatty acids was developed for their analysis by gas chromatography-mass spectrometry. The methyl esters of free fatty acids were obtained by reaction with methyl iodide in the solution of dipolar aprotic solvents and in the presence of solid bases. The mechanism of the methylation reaction with these reagents was investigated. Optimal conditions for the selective methylation of free fatty acids were established using different dipolar aprotic solvents and different solid bases. The possible transmethylation of covalently bonded fatty acids from plasma lipids has been investigated under different experimental conditions in order to be avoided. Total methylation of free fatty acids was achieved in 1 min at room temperature using methyl iodide and anhydrous potassium carbonate or sodium carbonate in dimethyl sulfoxide. Under these conditions, transmethylation of lipid-bound fatty acids was avoided. The methyl esters can be injected directly from the reaction solvents. A plasma volume of 50 μL was used without special purification. The detection limits were around 0.1 ng/μL. The proposed method avoids the drawbacks of the previous methods used for the one-step analysis of individual free fatty acids in human plasma.

Diet quality, general health and anthropometric outcomes in a Latin American population: evidence from the Colombian National Nutritional Survey (ENSIN) 2010

OBJECTIVE

Colombia is experiencing a nutrition transition, characterised by nutritionally poor diets and an increased prevalence of non-communicable diseases (NCD). We aimed to investigate the association between diet quality and general health outcomes related to the risk of NCD, in a nationally representative sample of Colombian adolescents and adults.

DESIGN

Cross-sectional analysis. The Alternative Healthy-Eating Index (AHEI) was derived to calculate diet quality. Adjusted regressions were used to examine the association between AHEI, self-perceived general health status (GHS) and anthropometric variables (i.e. age-specific z-scores for height, and BMI for adolescents; waist circumference and BMI for adults).

SETTING

Nationally representative data from the Colombian National Nutrition Survey (ENSIN) 2010.

PARTICIPANTS

Adolescents aged 10-17 years (n 6566) and adults aged ≥18 years (n 6750).

RESULTS

AHEI scores were similar between adolescents (mean 29·3 ± 7·2) and adults (mean 30·5 ± 7·2). In the whole sample, a better diet quality (higher AHEI score) was associated with worse self-perceived GHS (adjusted (a) β-coefficient: -0·004; P < 0·001) and with a smaller waist circumference ((a) β-coefficient: -0·06; P < 0·01). In adults, a higher AHEI score was negatively associated with BMI ((a) β-coefficient: -0·02; P < 0·05), whilst in adolescents it was associated with a reduced height-for-age z-score ((a) β-coefficient: -0·009; P < 0·001).

CONCLUSIONS

A better diet quality was associated with reduced prevalence of predictors of NCD and with some indicators of general health in the Colombian population. In light of the high prevalence of overweight, our findings support the need for public health interventions focused on sustainable positive changes in dietary habits in the general population.

Monosodium L-glutamate and fats change free fatty acid concentrations in intestinal contents and affect free fatty acid receptors express profile in growing pigs

BACKGROUND

Obesity and its related metabolic syndrome continue to be major public health problems. Monosodium L-glutamate (MSG) may cause metabolic diseases such as obesity. Meanwhile, the Chinese population has undergone rapid transition to a high-fat diet. There is little information available on the effect of MSG and fat alone, or in combination, on free fatty acids (FFAs), lipid metabolism and FFA receptors.

OBJECTIVE

The aim of this study was to evaluate the effects of MSG and fat alone, or in combination, on intestinal luminal FFAs and expression of gastrointestinal FFA receptors. The aim was also to test whether dietary fat and/or MSG could affect expression of genes related to fatty acid metabolism.

DESIGN

A total of 32 growing pigs were used and fed with four iso-nitrogenous and iso-caloric diets. Pigs in the four treatments received diets with one of two fat concentrations levels (4.4 and 9.4%) and one of two MSG dose levels (0 and 3%), in which most of the fat were brought by soybean oil. The concentration of short chain fatty acids (SCFAs) in cecum and colon, long chain fatty acids (LCFAs) in ileum, cecum and colon, and FFAs receptors expression in hypothalamus and gastrointestinal tract were determined.

RESULTS

MSG and/or fat changed intestinal luminal SCFAs, levels of LCFAs, and showed an antagonistic effect on most of LCFAs. Simultaneously, MSG and/or fat decreased the expression of FFA receptors in hypothalamus and gastrointestinal tract. MSG and/or fat promoted fat deposition through different ways in back fat.

CONCLUSION

Our results support that MSG and/or fat can alter intestinal luminal FFAs composition and concentration, especially LCFAs, in addition, the expression of FFA receptors in ileum and hypothalamus could be decreased. Moreover, MSG and/or fat can promote protein deposition in back fat, and affect the distribution and metabolism of fatty acids in the body tissues and the body's ability to perceive fatty acids; these results provide a reference for the occurrence of fat deposition and obesity caused by high-fat and monosodium glutamate diet.

Dietary calories and lipids synergistically shape adipose tissue cellularity during postnatal growth

Objective

The susceptibility to abdominal obesity and the metabolic syndrome is determined to a substantial extent during childhood and adolescence, when key adipose tissue characteristics are established. Although the general impact of postnatal nutrition is well known, it is not clear how specific dietary components drive adipose tissue growth and how this relates to the risk of metabolic dysfunction in adulthood.

Methods

Adipose tissue growth including cell proliferation was analyzed in juvenile mice upon dietary manipulation with in vivo nucleotide labeling. The proliferative response of progenitors to specific fatty acids was assayed in primary cultures. Long-term metabolic consequences were assessed through transient dietary manipulation post-weaning with a second obesogenic challenge in adulthood.

Results

Dietary lipids stimulated adipose tissue progenitor cell proliferation in juvenile mice independently of excess caloric intake and calorie-dependent adipocyte hypertrophy. Excess calories increased mitogenic IGF-1 levels systemically, whereas palmitoleic acid was able to enhance the sensitivity of progenitors to IGF-1, resulting in synergistic stimulation of proliferation. Early transient consumption of excess lipids promoted hyperplastic adipose tissue expansion in response to a second dietary challenge in adulthood and this correlated with abdominal obesity and hyperinsulinemia.

Conclusions

Dietary lipids and calories differentially and synergistically drive adipose tissue proliferative growth and the programming of the metabolic syndrome in childhood.

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Dietary fat accelerates adipose tissue progenitor proliferation in juvenile mice.

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Lipid-mediated proliferation is independent of excess calorie intake.

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Excess calories elevate IGF-1 levels and adipocyte hypertrophy.

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Palmitoleic acid enhances the proliferative response of progenitors to IGF-1.

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Lipids and calories in childhood program features of the adult metabolic syndrome.

Metabolomic Salivary Signature of Pediatric Obesity Related Liver Disease and Metabolic Syndrome

Pediatric obesity-related metabolic syndrome (MetS) and nonalcoholic fatty liver disease (NAFLD) are increasingly frequent conditions with a still-elusive diagnosis and low-efficacy treatment and monitoring options. In this study, we investigated the salivary metabolomic signature, which has been uncharacterized to date. In this pilot-nested case-control study over a transversal design, 41 subjects (23 obese patients and 18 normal weight (NW) healthy controls), characterized based on medical history, clinical, anthropometric, and laboratory data, were recruited. Liver involvement, defined according to ultrasonographic liver brightness, allowed for the allocation of the patients into four groups: obese with hepatic steatosis ([St+], n = 15) and without hepatic steatosis ([St–], n = 8), and with (n = 10) and without (n = 13) MetS. A partial least squares discriminant analysis (PLS-DA) model was devised to classify the patients’ classes based on their salivary metabolomic signature. Pediatric obesity and its related liver disease and metabolic syndrome appear to have distinct salivary metabolomic signatures. The difference is notable in metabolites involved in energy, amino and organic acid metabolism, as well as in intestinal bacteria metabolism, possibly reflecting diet, fatty acid synthase pathways, and the strict interaction between microbiota and intestinal mucins. This information expands the current understanding of NAFLD pathogenesis, potentially translating into better targeted monitoring and/or treatment strategies in the future.

Performance of Waist-To-Height Ratio, Waist Circumference, and Body Mass Index in Discriminating Cardio-Metabolic Risk Factors in a Sample of School-Aged Mexican Children

The most common tools used to screen for abdominal obesity are waist circumference (WC) and waist-to-height ratio (WHtR); the latter may represent a more suitable tool for the general non-professional population. The objective of this study was to evaluate the association of WHtR, WC, and body mass index with lipidic and non-lipidic cardio-metabolic risk factors and the prediction capability of each adiposity indicator in a sample of school-aged Mexican children. Overall, 125 children aged 6 to 12 years were analyzed. Anthropometric, biochemical, and dietary parameters were assessed. Receiving operating characteristic (ROC) analysis and univariate and multivariate linear and logistic regression analyses were performed. All the three adiposity indicators showed significant areas under the ROC curve (AURC) greater than 0.68 for high low-density lipoprotein cholesterol (LDL-c), triglycerides, and atherogenic index of plasma, and low high-density lipoprotein cholesterol (HDL-c). A significant increased risk of having LDL-c ≥ 3.4 mmol/L was observed among children with WHtR ≥ 0.5 as compared to those with WHtR < 0.5 (odds ratio, OR: 2.82; 95% confidence interval, CI: 0.75–7.68; p = 0.003). Fasting plasma glucose was not associated with any of the adiposity parameters. WHtR performed similarly to WC and z-BMI in predicting lipidic cardio-metabolic risk factors; however, a WHtR ≥ 0.5 was superior in detecting an increased risk of elevated LDL-c.