Long-chain polyunsaturated fatty acids in plasma lipids of obese children

Bioactive compounds in childhood obesity and associated metabolic complications: Current evidence, controversies and perspectives

Obesity represents the most frequent chronic disease among children worldwide, with a significant global burden on society. Metabolically unhealthy obesity (MUO) can affect children since their first years of life, and novel therapeutic strategies to tackle metabolic complications are under investigation. This review focuses on bioactive compounds and their possible beneficial effects on obesity, particularly omega-3, docosahexaenoic acid, vitamin D, biotics, polysaccharide macromolecules, polyphenols, inositols, alpha lipoic acid, and bromelaine. Our aim is to summarize current evidence about bioactive compounds in the treatment of obesity, highlighting recent findings on their use in children and adolescents. Most studied molecules are omega-3 and vitamin D, despite the heterogeneity between the studies. Moreover, given the emerging interest in the gut-brain axis in the link between metabolic health and microbiota, various studies on prebiotics, probiotics, synbiotics, postbiotics and polysaccharide macromolecules have been considered. Some preclinical studies seem to highlight a possible role of the polyphenols, even if their clinical evidence is still discussed. Lastly, we describe possible effects of inositols and alpha-lipoic acid. Despite some dietary supplements seem to be promising in overweight subjects, only in a few of them a dose/response efficacy has been found in the pediatric age. Innovative, well-designed and targeted clinical trials are then needed to prove the beneficial effects of these compounds that could support the standard behavioral therapy for obesity.

Metabolome-Wide Associations of Gestational Weight Gain in Pregnant Women with Overweight and Obesity

Excessive gestational weight gain (GWG) is associated with adverse pregnancy outcomes. This metabolome-wide association study aimed to identify metabolomic markers for GWG. This longitudinal study included 39 Black and White pregnant women with a prepregnancy body mass index (BMI) of ≥ 25 kg/m2. Untargeted metabolomic profiling was performed using fasting plasma samples collected at baseline (mean: 12.1 weeks) and 32 weeks of gestation. The associations of metabolites at each time point and changes between the two time points with GWG were examined by linear and least absolute shrinkage and selection operator (LASSO) regression analyses. Pearson correlations between the identified metabolites and cardiometabolic biomarkers were examined. Of the 769 annotated metabolites, 88 metabolites at 32 weeks were individually associated with GWG, with four (phosphatidylcholine (PC) 34:4, triacylglycerol (TAG) 52:6, arachidonic acid, isoleucine) jointly associated with GWG (area under the receiver operating characteristic curve (AUC) for excessive GWG: 0.80, 95% CI: 0.67, 0.93). No correlations were observed between the 88 metabolites and insulin, C-peptide, and high-sensitivity C-reactive protein at 32 weeks. Twelve metabolites at baseline (AUC for excessive GWG: 0.80, 95% CI: 0.62, 0.99) and three metabolite changes (AUC for excessive GWG: 0.73, 95% CI: 0.44, 1.00) were jointly associated with GWG. We identified novel metabolites in the first and third trimesters associated with GWG, which may shed light on the pathophysiology of GWG.

Effect of General Adiposity and Central Body Fat Distribution on the Circulating Metabolome: A Multicohort Nontargeted Metabolomics Observational and Mendelian Randomization Study

Obesity is associated with adverse health outcomes, but the metabolic effects have not yet been fully elucidated. We aimed to investigate the association between adiposity and circulating metabolites and to address causality with Mendelian randomization (MR). Metabolomics data were generated with nontargeted ultraperformance liquid chromatography coupled to time-of-flight mass spectrometry in plasma and serum from three population-based Swedish cohorts: ULSAM (N = 1,135), PIVUS (N = 970), and TwinGene (N = 2,059). We assessed associations of general adiposity measured as BMI and central body fat distribution measured as waist-to-hip ratio adjusted for BMI (WHRadjBMI) with 210 annotated metabolites. We used MR analysis to assess causal effects. Lastly, we attempted to replicate the MR findings in the KORA and TwinsUK cohorts (N = 7,373), the CHARGE Consortium (N = 8,631), the Framingham Heart Study (N = 2,076), and the DIRECT Consortium (N = 3,029). BMI was associated with 77 metabolites, while WHRadjBMI was associated with 11 and 3 metabolites in women and men, respectively. The MR analyses in the Swedish cohorts suggested a causal association (P value <0.05) of increased general adiposity and reduced levels of arachidonic acid, dodecanedioic acid, and lysophosphatidylcholine (P-16:0) as well as with increased creatine levels. The results of the replication effort provided support for a causal association of adiposity with reduced levels of arachidonic acid (P value = 0.03). Adiposity is associated with variation of large parts of the circulating metabolome; however, further investigation of causality is required in well-powered cohorts.

Enhanced Muscle Strength in Dyslipidemic Mice and Its Relation to Increased Capacity for Fatty Acid Oxidation

Dyslipidemia is commonly linked to skeletal muscle dysfunction, accumulation of intramyocellular lipids, and insulin resistance. However, our previous research indicated that dyslipidemia in apolipoprotein E and low-density lipoprotein receptor double knock-out mice (ApoE/LDLR -/-) leads to improvement of exercise capacity. This study aimed to investigate in detail skeletal muscle function and metabolism in these dyslipidemic mice. We found that ApoE/LDLR -/- mice showed an increased grip strength as well as increased troponins, and Mhc2 levels in skeletal muscle. It was accompanied by the increased skeletal muscle mitochondria numbers (judged by increased citrate synthase activity) and elevated total adenine nucleotides pool. We noted increased triglycerides contents in skeletal muscles and increased serum free fatty acids (FFA) levels in ApoE/LDLR -/- mice. Importantly, Ranolazine mediated inhibition of FFA oxidation in ApoE/LDLR -/- mice led to the reduction of exercise capacity and total adenine nucleotides pool. Thus, this study demonstrated that increased capacity for fatty acid oxidation, an adaptive response to dyslipidemia leads to improved cellular energetics that translates to increased skeletal muscle strength and contributes to increased exercise capacity in ApoE/LDLR -/- mice.

Increased adiposity in children with obesity is associated with low red blood cell omega-3 fatty acid status and inadequate polyunsaturated fatty acid dietary intake

The association between total dietary fat intake and measures of body fatness in children with obesity remains inconsistent. This study aimed to determine whether dietary long-chain polyunsaturated fatty acids (LCPUFA) and LCPUFA status relate to body composition in children with obesity. Children (n = 63, 9.0 ± 0.2 year, BMI Z-score 3.1 ± 0.2) were divided into tertiles of percentage body fat assessed by dual-energy X-ray absorptiometry. Diet was assessed 3-days food diaries. Fatty acid proportions in red blood cells (RBC) were measured by gas chromatography. Data stratified by sex and Tanner stages were compared with a MIXED model ANOVA. Associations between RBC fatty acid status and dietary intakes were examined with Spearman correlation. Moderate correlations were observed between RBC eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) proportions, dietary EPA and DHA (r = 0.39, P < .05) as well as fish servings (r = 0.33, P < .05). Dietary LCPUFA did not differ among tertiles. Children in tertile 3 had lower RBC α-linolenic acid (-40%) and EPA + DHA (-15%) proportions adjusted for age, Tanner stages and race compared with tertile 1. The lower omega-3 LCPUFA status in children with greater adiposity is consistent with suboptimal intakes of omega-3 LCPUFA and fish in the diet.

Arachidonic acid status negatively associates with forearm bone outcomes and glucose homeostasis in children with an overweight condition or obesity

Long-chain polyunsaturated fatty acids are implicated in musculoskeletal health in adults. This study examined whether fatty acid status relates to bone health outcomes in children with overweight condition or obesity (body mass index z score, 3.1 ± 0.1; age, 9.0 ± 0.2 years; n = 108). Nondominant forearm bone density (distal one-third), geometry (4% site), and soft tissue composition (66%) were assessed using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Red blood cell (RBC) fatty acid profile and indices of glucose homeostasis were measured. Differences in outcomes among RBC arachidonic acid (AA, C20:4n-6) tertiles were tested using mixed-model ANOVA. Ultra-, mid-, and total-distal forearm bone mineral content, adjusted for sex, age, percentage body fat, race, and forearm length, were 10% to 13% greater in children in the first AA tertile relative to the third. Children in the second tertile had the highest bone cross-sectional area and estimated strength at the 66% radius. Muscle cross-sectional area was 15% lower in the third tertile compared with the first, along with higher fasting insulin concentrations (27%) and homeostasis model of assessment estimate of insulin resistance (31%). Higher RBC AA status aligns with deficits in forearm bone mass, geometry, and muscle mass in children with excess adiposity and early signs of insulin resistance. Novelty Higher arachidonic acid status is associated with lower forearm bone mass in children with overweight condition or obesity. Children with higher arachidonic acid status had increased fasting insulin concentrations and indices of insulin resistance.

Arachidonic acid exacerbates diet-induced obesity and reduces bone mineral content without impacting bone strength in growing male rats

Long-chain polyunsaturated fatty acids modulate bone mass and adipocyte metabolism. Arachidonic acid (AA, C20:4 n-6) is elevated in obesity and postulated to stimulate bone resorption. This study aimed to determine the effect of AA on bone mass, quality, and adiposity in diet-induced obesity during growth. Male Sprague-Dawley rats (n=42, 4-week) were randomized into groups fed a control diet (CTRL, AIN-93G), high-fat diet (HFD, 35% kcal fat) or HFD + AA (1% w/w diet) for 6 weeks. Body composition, bone mineral density and microarchitecture were measured using dual-energy X-ray absorptiometry and micro-computed tomography. Red blood cell fatty acid profile was measured with gas chromatography. Group differences were evaluated using repeated measures two-way analysis of variance with Tukey-Kramer post hoc testing. Total energy intake did not differ among diet groups. At week 6, HFD + AA had significantly greater body fat % (12%), body weight (6%) and serum leptin concentrations (125%) than CTRL, whereas visceral fat (mass and %, assessed with micro-computed tomography) was increased in both HFD and HFD + AA groups. HFD + AA showed reduced whole body bone mineral content and femur mid-diaphyseal cortical bone cross-sectional area than HFD and CTRL, without impairment in bone strength. Contrarily, HFD + AA had greater femur metaphyseal trabecular vBMD (35%) and bone volume fraction (5%) compared to controls. Inclusion of AA elevated leptin concentrations in male rats. The early manifestations of diet-induced obesity on bone mass were accelerated with AA. Studies of longer duration are needed to clarify the effect of AA on peak bone mass following growth cessation.

Effect of weight loss on circulating fatty acid profiles in overweight subjects with high visceral fat area: a 12-week randomized controlled trial

Background

Significant associations between visceral fat and alterations in plasma fatty acids have been identified in overweight individuals. However, there are scant data regarding the relationships of the visceral fat area (VFA) with the plasma fatty acid profiles and desaturase activities following weight loss. We investigated the effect of weight loss with mild calorie restriction on the circulating fatty acid profiles and desaturase activities in nondiabetic overweight subjects with high VFA.

Methods

Eighty overweight subjects with high VFA (L4 VFA ≥100 cm²) were randomized into the 12-week mild-calorie-restriction (300 kcal/day) or control groups.

Results

Comparison of the percent of body weight changes between groups revealed that the weight-loss group had greater reductions in body weight. The VFA decreased by 17.7 cm² from baseline in the weight-loss group (P < 0.001). At follow-up, the weight-loss group showed greater reductions in serum triglycerides, insulin, and HOMA-IR than the control group. Significantly greater reductions in total saturated fatty acids, palmitic acid, stearic acid, total monounsaturated fatty acids, palmitoleic acid, oleic acid, eicosadienoic acid, and dihomo-γ-linolenic acid levels were detected in the weight-loss group compared with the control group after adjusting for baseline values. Following weight loss, C16 Δ9-desaturase activity was significantly decreased and Δ5-desaturase activity was significantly increased, and the changes were greater in the weight-loss group than in the control group.

Conclusions

The results suggest that mild weight loss improves abdominal obesity, overall fatty acid profiles, and desaturase activities; therefore, mild calorie restriction has potential health benefits related to obesity-related diseases in overweight subjects with high VFA.

Trial registration

NCT02992639. Retrospectively registered 11 December 2016.

Linoleic acid and the pathogenesis of obesity

The modern Western diet has been consumed in developed English speaking countries for the last 50 years, and is now gradually being adopted in Eastern and developing countries. These nutrition transitions are typified by an increased intake of high linoleic acid (LA) plant oils, due to their abundance and low price, resulting in an increase in the PUFA n-6:n-3 ratio. This increase in LA above what is estimated to be required is hypothesised to be implicated in the increased rates of obesity and other associated non-communicable diseases which occur following a transition to a modern Westernised diet. LA can be converted to the metabolically active arachidonic acid, which has roles in inducing inflammation and adipogenesis, and endocannabinoid system regulation. This review aims to address the possible implications of excessive LA and its metabolites in the pathogenesis of obesity.

Association of Plasma Lipids Fatty Acid Composition With Metabolic Profile of Czech Adolescents

Obesity in childhood increases the risk of obesity in adulthood and is predictive for the development of metabolic disorders. The fatty acid composition is associated with obesity and obesity-associated disorders. We investigated the relationship between serum fatty acids composition, adiposity, lipids profile, parameters of glucose metabolism and leptin. The study subjects were 380 adolescents aged 15.0-17.9 years. The study's variables included anthropometric measurements, levels of serum lipids and hormonal parameters. Individual fatty acids were determined in plasma by gas-liquid chromatography. Palmitoleic acid (16:1n-7, PA) significantly positively correlated with percentage of body fat. Saturated fatty acids in phospholipids (PL) positively correlated with BMI and percentage of body fat. PA content in all lipids classes positively correlated with total cholesterol (TC), HDL cholesterol, triglycerides (TG) levels. Stearoyl-CoA desaturase (SCD) activity positively correlated with percentage of body fat and positive correlations of SCD and PA level with leptin were found. Plasma PA content and SCD are associated with adiposity and leptin in obese adolescents. No significant correlation between PA level and insulin resistance was found. Palmitoleate positively correlated with TC, HDL cholesterol, TG and LDL cholesterol levels.

Arachidonic acid impairs hypothalamic leptin signaling and hepatic energy homeostasis in mice

Epidemiological evidence suggests that the consumption of a diet high in n-6 polyunsaturated fatty acids (PUFA) is associated with the development of leptin resistance and obesity. We aim to examine the central effect of n-6 PUFA, arachidonic acid (ARA) on leptin sensitivity and leptin-regulated hepatic glucose and lipid metabolism. We found that intracerebroventricular injection of ARA (25 nmol/day) for 2.5 days reversed the effect of central leptin on hypothalamic JAK2, pSTAT3, pAkt, and pFOXO1 protein levels, which was concomitant with a pro-inflammatory response in the hypothalamus. ARA also attenuated the effect of central leptin on hepatic glucose and lipid metabolism by reversing the mRNA expression of the genes involved in gluconeogenesis (G6Pase, PEPCK), glucose transportation (GLUT2), lipogenesis (FAS, SCD1), and cholesterol synthesis (HMG-CoA reductase). These results indicate that an increased exposure to central n-6 PUFA induces central cellular leptin resistance with concomitant defective JAK2-STAT3 and PI3K-Akt signaling.

Long-chain polyunsaturated fatty acid status in obesity: a systematic review and meta-analysis

Long-chain polyunsaturated fatty acid (LCPUFA) status has recently been related to the pathogenesis of obesity. Our aims were to systematically review observational studies investigating LCPUFA status from different blood compartments in overweight or obese subjects and to assess the relationship between LCPUFA profile and obesity. The Ovid MEDLINE, Scopus and Cochrane Library CENTRAL databases were searched from inception to January 2014. The meta-analysis showed significant differences in the LCPUFA composition of total plasma lipids, plasma phospholipids and plasma cholesteryl esters between overweight or obese subjects and controls. Dihomo-γ-linolenic acid (DGLA) values were significantly higher in overweight or obese subjects compared with controls in all the investigated biomarkers. In addition, the DGLA/linoleic acid ratio (surrogate parameter for Δ6 desaturase activity) in plasma phospholipids was significantly elevated (mean difference [MD]: 0.05; 95% confidence interval [CI]: 0.02, 0.08; n = 280), while the arachidonic acid/DGLA ratio (surrogate parameter for Δ5 desaturase activity) was significantly decreased (MD: -0.55; 95% CI: -0.71, -0.39; n = 347) in overweight or obese subjects compared with controls. The results of the present meta-analysis confirm that LCPUFA profile is altered in obesity and suggest that the differences observed in desaturase activities may be responsible for the disturbed LCPUFA metabolism in obesity.

Low n-3 long-chain polyunsaturated fatty acids in newly diagnosed celiac disease in children with preexisting type 1 diabetes mellitus

OBJECTIVE

Fat malabsorption can occur in celiac disease (CD) owing to villus atrophy and inflammation of small intestinal mucosa. Abnormal fatty acid (FA) status of intestinal mucosa in children with CD was reported earlier. Previously we found significantly reduced availability of n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) in children and young adults with type 1 diabetes mellitus (DM). The aim of this study was to investigate FAs in plasma lipid classes in children with newly diagnosed CD with or without preexisting DM.

METHODS

FA composition of plasma samples of children with untreated CD only (n = 20) and with preexisting DM (CDDM, n = 8) were compared with those of healthy controls (n = 21). Detailed analysis of phospholipid, triacylglycerol, and sterol ester FAs was performed by high-resolution capillary gas-liquid chromatography.

RESULTS

Significantly decreased docosapentaenoic (C22:5n-3), docosahexaenoic (C22:6n-3), n-3 polyunsaturated fatty acids (n-3 PUFA), and n-3 LCPUFA values were found in CDDM group compared with controls and patients with CD. When compared with healthy controls, no significant difference was found in plasma FAs of children with newly diagnosed CD only.

CONCLUSIONS

Children with CDDM showed marked signs of reduced availability of n-3 PUFA and n-3 LCPUFA in circulating lipids. Although different tissues express membrane FAs differently, our present study suggests that CD on its own does not necessarily lead to detectable disturbances of essential FA metabolism in plasma and supports the concept that DM has significant impact on plasma FA composition in children.

Association of changes in body fatness and fatty acid composition of plasma phospholipids during early puberty in Japanese children

AIMS

Plasma fatty acid composition can change with age, reflecting diet and levels of desaturating enzymes such as stearoyl-CoA desaturase (SCD), delta-6 desaturase (D6D) and delta-5 desaturase (D5D), which contribute to the development of insulin resistance. This study analyzed longitudinal changes in fatty acid composition in Japanese children during early puberty and the association between changes in desaturase indices and changes in body fatness and insulin resistance.

METHODS

The study included 77 children (38 boys and 39 girls) aged 9.6±0.5 years. Relative weight (RW) and waist-to-height ratio (WHtR) were determined. The fatty acid composition of plasma phospholipids was analyzed by gas chromatography, and the desaturase indices were calculated: SCD (16:1n-7/16:0: SCD16 and 18:1n-9/18:0: SCD18), D6D (20:3n-6/18:2n-6) and D5D (20:4n-6/20:3n-6) in 2006 and 2009.

RESULTS

Obese children showed higher dihomo-gamma linolenic acid (DGLA; 20:3n-6), a higher D6D index and lower D5D index than non-obese children. Longitudinal changes in fatty acid com-position were generally similar in both sexes. Increased D6D index and DGLA and decreased D5D index were significantly associated with increased WHtR in boys and girls. In addition, increased D6D index was associated with an increased homeostasis model of assessment ratio (HOMA-R) only in girls.

CONCLUSION

The change in abdominal adiposity is a determinant of longitudinal changes in D6D and D5D indices and DGLA during early puberty.

A comparative validation of a child food frequency questionnaire using red blood cell membrane fatty acids

BACKGROUND/OBJECTIVES

There are limited validated tools available for the assessment of dietary intake in pediatric populations. This report describes a comparative validation study of selected fatty acid intakes in children assessed by food frequency questionnaire (FFQ), compared with erythrocyte membrane fatty acids.

SUBJECTS/METHODS

Overall, 46 overweight and 47 healthy-weight children aged 5-12 years (mean±SD, 9.1±1.3years, body mass index 20.5±4.0) were recruited; dietary fatty acid intakes assessed by parent report using a 135-item semi-quantitative FFQ, were compared with selected child erythrocyte membrane fatty acids assessed from fasting samples using gas chromatography. Spearman's rank correlation coefficients were calculated between fatty acid intake estimates (% of energy) and erythrocyte membrane concentrations (%mol/mol).

RESULTS

Significant correlations were found between dietary and erythrocyte eicosapentanoic acid (EPA) concentration (r=0.24, P<0.05) with a statistical trend for total omega three (∑n-3) fatty acids (r=0.22, P=0.06) and linoleic acid (r=0.32, P=0.07) in the healthy-weight children only.

CONCLUSION

Parental report of selected child fatty acid intakes using an FFQ can be used to provide an estimate of child intake of EPA, but further work is required to quantify this relationship for other fatty acids and in other populations.

Mental state attribution and body configuration in women

Body configuration is a sexually dimorphic trait. In humans, men tend to have high shoulder-to-hip ratios. Women in contrast, often have low waist-to-hip ratios (WHR); i.e., narrow waists and broad hips that approximate an hour-glass configuration. Women with low WHR’s are rated as more attractive, healthier, and more fertile. They also tend to have more attractive voices, lose their virginity sooner, and have more sex partners. WHR has also been linked with general cognitive performance. In the present study we expand upon previous research examining the role of WHR in cognition. We hypothesized that more feminine body types, as indexed by a low WHR, would be associated with cognitive measures of the female “brain type,” such as mental state attribution and empathy because both may depend upon the activational effects of estrogens at puberty. We found that women with low WHRs excel at identifying emotional states of other people and show a cognitive style that favors empathizing over systemizing. We suggest this relationship may be a byproduct of greater gluteofemoral fat stores which are high in the essential fatty acids needed to support brain development and cellular functioning. It is interesting to note that our findings suggest lower WHR females, who are more likely to be targeted for dishonest courtship, may be better at identifying disingenuous claims of commitment.

A high-fat diet induces bone loss in mice lacking the Alox5 gene

5-Lipoxygenase catalyzes leukotriene generation from arachidonic acid. The gene that encodes 5-lipoxygenase, Alox5, has been identified in genome-wide association and mouse Quantitative Trait Locus studies as a candidate gene for obesity and low bone mass. Thus, we tested the hypothesis that Alox5(-/-) mice would exhibit metabolic and skeletal changes when challenged by a high-fat diet (HFD). On a regular diet, Alox5(-/-) mice did not differ in total body weight, percent fat mass, or bone mineral density compared with wild-type (WT) controls (P < 0.05). However, when placed on a HFD, Alox5(-/-) gained more fat mass and lost greater areal bone mass vs. WT (P < 0.05). Microarchitectural analyses revealed that on a HFD, WT showed increases in cortical area (P < 0.01) and trabecular thickness (P < 0.01), whereas Alox5(-/-) showed no change in cortical parameters but a decrease in trabecular number (P < 0.05) and bone volume fraction compared with WT controls (P < 0.05). By histomorphometry, a HFD did not change bone formation rates of either strain but produced an increase in osteoclast number per bone perimeter in Alox5(-/-) mice (P < 0.03). In vitro, osteoclastogenesis of marrow stromal cells was enhanced in mutant but not WT mice fed a HFD. Gene expression for Rankl, Pparg, and Cox-2 was greater in the femur of Alox5(-/-) than WT mice on a HFD (P < 0.01), but these increases were suppressed in the Alox5(-/-) mice after 8 wk of treatment with celecoxib, a cyclooxygenase-2 inhibitor. In sum, there is a strong gene by environmental interaction for bone mass when mice lacking the Alox5 gene are fed a HFD.

Role of dietary factors and food habits in the development of childhood obesity: a commentary by the ESPGHAN Committee on Nutrition

This Comment by the Committee on Nutrition of the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition aims to provide a summary of the role of nutrition-related factors on obesity prevention in children ages 2 to 18 years. This Comment emphasizes that dietary interventions should be incorporated into a multidisciplinary strategy for obesity prevention. No single nutrient has been unequivocally associated with the development of obesity. Methodological limitations in study design and the complex nature of obesity must be taken into account when interpreting the association with reported dietary factors. Energy intake should be individually determined, taking into account energy expenditure and growth. Preferential intake of slowly absorbed carbohydrates and limiting the ingestion of rapidly absorbed carbohydrates and simple sugars should be promoted. No specific recommendations for macronutrient intakes to prevent obesity can be made. Plant foods can be used as the main food contributors to a well-balanced diet with adequate monitoring of nutrient intake. Plain water should be promoted as the main source of fluids for children instead of sugar-sweetened beverages. Children should eat at least 4 meals, including breakfast, every day. Regular family meals should be encouraged. Regular consumption of fast food with large portion sizes and high energy density should be avoided. Healthy food options should be promoted for snacking. Food portion sizes should be appropriate for age and body size. Nutrition and lifestyle education aimed at the prevention of obesity should be included in the routine care of children by health care professionals.

Inflammatory lipid mediators in adipocyte function and obesity

Survival of multicellular organisms depends on their ability to fight infection, metabolize nutrients, and store energy for times of need. Unsurprisingly, therefore, immunoregulatory and metabolic mechanisms interact in human conditions such as obesity. Both infiltrating immunoinflammatory cells and adipocytes play critical roles in the modulation of metabolic homeostasis, so it is important to understand factors that regulate both adipocyte and immune cell function. A currently favored paradigm for obesity-associated metabolic dysfunction is that chronic macronutrient and/or lipid overload (associated with adiposity) induces cellular stress that initiates and perpetuates an inflammatory cycle and pathophysiological signaling of immunoinflammatory cells and adipocytes. Many lipid mediators exert their biological effects by binding to cognate receptors, such as G-protein-coupled receptors and Toll-like receptors. This process is tightly regulated under normal physiological conditions, and any disruption can initiate disease processes. Observations that cellular lipid loading (associated with adiposity) initiates inflammatory events has encouraged studies on the role of lipid mediators. In this review, we speculate that lipid mediators act on important immune receptors to induce low-grade tissue inflammation, which leads to adipocyte and metabolic dysfunction.

Plasma n-3 Polyunsaturated Fatty Acids are negatively associated with obesity

The objective of the present study was to investigate the relationship between plasma n-3 PUFA composition and weight status. A total of 124 adults, stratified by weight status: healthy weight (n 21), overweight (n 40) and obese (n 63) were recruited. Fasting blood samples, anthropometric measures and body composition were collected. Plasma fatty acid composition was determined by GC. BMI, waist circumference and hip circumference were inversely correlated with n-3 PUFA, EPA and DHA (P < 0.05 for all) in the obese group. Obese individuals had significantly lower plasma concentrations of total n-3 PUFA, compared with healthy-weight individuals (4.53 (SD 1.11) v. 5.25 (SD 1.43) %). When subjects were pooled and stratified into quartiles of total n-3 PUFA, a significant inverse trend was found for BMI (P = 0.002), waist circumference and hip circumference (P = 0.01 and P < 0.001 respectively). Higher plasma levels of total n-3 PUFA are associated with a healthier BMI, waist circumference and hip circumference. Our findings suggest that n-3 PUFA may play an important role in weight status and abdominal adiposity.

Decreased activity of desaturase 5 in association with obesity and insulin resistance aggravates declining long-chainn-3 fatty acid status in Cree undergoing dietary transition

Emerging evidence shows that desaturase 5 (Δ5), the key regulator in the synthesis of highly unsaturated long-chain fatty acids (HUFA), is modulated by factors including adiposity, diet and insulin resistance. We explored the association of these factors in a cross-sectional study within a high-risk Cree population. Anthropometric measures and fasting blood glucose and insulin were analysed. Δ5 was estimated as the 20 : 4n-6:20 : 3n-6 ratio in erythrocyte membranes. The setting of the present study was the Mistissini community in the Cree Territory of Québec, Canada with ninety-eight female and sixty-eight male subjects aged 20–88 years. Obesity (BMI ≥ 30 kg/m2) was prevalent across age groups. Δ5 was inversely associated with BMI (Spearman's correlation coefficient (rs) − 0·175;P = 0·03) and positively associated with age (rs0·593;P < 0·0001), which was driven by age-related increases in dietary intake ofn-3 fatty acids and decreases in 20 : 3n-6. Homeostasis model assessment of insulin resistance (HOMA-IR) was significantly inversely associated with Δ5 in age-adjusted linear regression analyses in normoglycaemic individuals (β − 2·110 (se0·566);P < 0·001), whereas no association was observed among glucose-intolerant individuals (interaction termP = 0·03). In contrast, there were no significant interactions indicating differences in the slope for each of the adiposity measures in their associations with Δ5. The present study indicates that the dietary transition of reduced consumption of fish among younger Cree may compound the effects of obesity and emerging insulin resistance which, in turn, could reduce bioavailability of HUFAn-3 (through reduced Δ5 activity). Also, the study suggests that disease progression is an important consideration when evaluating correlates of Δ5 activity in observational studies.

Fatty acid composition of erythrocyte membrane lipids in healthy subjects from birth to young adulthood

The fatty acid composition of erythrocyte membrane lipids may better reflect the fatty acid status of the organism than the fatty acid composition of plasma lipids. The present study aimed to provide normal values for erythrocyte fatty acid composition in a sizeable group of healthy subjects throughout the paediatric age group. The fatty acid composition of erythrocyte membrane phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipids was determined by high-resolution capillary gas chromatography in 188 apparently healthy subjects from birth to young adulthood (newborns: n=17, infants: n=97, children: n=38, young adults: n=36). The values of linoleic acid (C18:2n-6) increased steadily between birth and young adulthood (newborns: 6.49 [2.45], infants: 14.51 [4.32], children: 18.10 [3.25], young adults: 19.87 [2.03], PC lipids, shown as median [interquartile range, IQR], p<0.001]. In contrast, the values of arachidonic acid (C20:4n-6) were significantly higher in children than in young adults (PC: 9.48 [6.64] versus 8.00 [1.85], PE: 26.38 [3.98] versus 24.46 [2.44], p<0.05). The values of alpha-linolenic acid (C18:3n-3) decreased significantly between children and young adults (0.14 [0.11] versus 0.08 [0.07], PE lipids, p<0.05). The values of docosahexaenoic acid (C22:6n-3) increased significantly from infancy through childhood up to young adulthood (PE: 4.20 [2.41] and 4.55 [0.97] and 6.66 [1.81], p<0.05 and 0.001, respectively). We found significantly higher total trans isomeric fatty acid values in newborns than in infants (PC: 0.60 [0.27] versus 0.43 [0.19], p<0.05; PE: 0.66 [0.76] versus 0.30 [0.26], p<0.001). From the results, we conclude that: (1) the data obtained in the present study may serve as reference values in the evaluation of the fatty acid status from birth to young adulthood; (2) the significantly higher values of trans fatty acids at birth than at later stages of life may be of concern, because previous studies suggested that trans fatty acids may interfere with essential fatty acid metabolism during the perinatal period.

Long-chain polyunsaturated fatty acids in breast milk and early weight gain in breast-fed infants

The long-chain PUFA (LCPUFA) content of an infant's diet might affect early weight gain. In early trials on supplementation of formula feeding n-3 LCPUFA affected weight gain adversely. n-6 LCPUFA are thought to promote adipose tissue development and might be associated with higher weight gain. We studied the association between the natural n-3 and n-6 LCPUFA content of breast milk of Dutch women and weight and BMI gain of their breast-fed infants in the first year of life. The children in this study were enrolled in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study and were born in 1996-1997 in The Netherlands. Parents reported their child's weight and length in a questionnaire. Of a subgroup of the total population breast-milk samples were collected (n 244). The fatty acid composition of breast milk was determined by GLC and expressed as weight percentages. Linear regression was used for data analysis. Mean gain in weight, length and BMI per week from birth to 1 year of age was 119.5 (SD 16.1) g, 0.48 (SD 0.05) cm and 0.06 (SD 0.03) kg/m2, respectively. The associations between n-6 and n-3 LCPUFA in breast milk, and infant weight, length and BMI gain were weak and inconsistent. The n-3 and n-6 LCPUFA content in breast milk did not affect weight or BMI gain in the first year of life in breast-fed term infants.

Changes in plasma fatty acid composition after intake of a standardised breakfast in prepubertal obese children

Obese patients typically show a pattern of dyslipidaemia and changes in plasma fatty acid composition reflecting abnormalities in lipoprotein metabolism and dietary habits. Animals and obese adults have been widely studied; however, contradictory results have been published in children. The objective was to assess changes in plasma fatty acid composition in total plasma lipids and plasma lipid fractions in obese prepubertal children compared with those of normal weight and to evaluate changes in postprandial plasma fatty acids during a 3 h period after intake of a standardised breakfast. The study was a case-control study with thirty-four obese and twenty normal-weight prepubertal children (Tanner 1). Anthropometric and metabolic variables and fatty acid concentrations were measured in plasma and its fractions. Liquid chromatography was used to separate lipid fractions and GLC to quantify fatty acids. Plasma total fatty acids (TFA), SFA, MUFA and PUFA concentrations were higher in obese than in control children. Except for 18 : 0, 18 : 3n-3, 20 : 4n-6 and n-3 PUFA, all fatty acids in TAG were also elevated in the obese group. Fatty acids 16 : 1n-7, 18 : 0, 18 : 1n-9, 20 : 2n-6, TFA and MUFA significantly decreased between the 2nd and 3rd hour in normal-weight v. obese children. The concentration of 16 : 1n-7 was positively and the proportion of 20 : 4n-6 inversely associated with a significant increase in risk of obesity. Obese prepubertal children show an altered plasma fatty acid profile and concentrations, mainly related to the TAG fatty acid profile, with a lower clearance of fatty acids v. normal-weight prepubertal children.

Association of n-6 long-chain polyunsaturated fatty acids to -866 G/A genotypes of the human uncoupling protein 2 gene in obese children

AIM

To investigate the association of plasma fatty acids with the -866 G/A polymorphism of uncoupling protein 2 (UCP2) in obese children.

METHODS

Fatty acid composition of plasma phospholipids and sterol esters were investigated in 80 obese children.

RESULTS

Values of dihomo-gamma-linolenic acid (C20:3n-6) were significantly lower in children with the -866 A/A (n = 12) than in those with the -866 G/A (n = 34) or -866 G/G (n = 34) genotype in plasma phospholipids (3.01 [0.42] vs. 3.56 [1.02] vs. 3.53 [0.84], % weight/weight, median [interquartile range], p < 0.05), and were significantly lower in children with the -866 A/A genotype than in the other two groups in plasma sterol esters (0.73 [0.22] vs. 0.92 [0.23] vs. 0.94 [0.25], p < 0.05). Phospholipid C20:3n-6 and arachidonic acid (C20:4n-6) values showed only in children with the -866 G/G and -866 G/A genotypes significant positive correlations with plasma insulin concentrations.

CONCLUSIONS

Significantly lower values of C20:3n-6 can be detected in obese children with the homozygous (-866 A/A) mutation of UCP2 than in equally obese children with heterozygous mutation or the normal genotype. High glucose-stimulated insulin response is associated with high plasma C20:3n-6 and C20:4n-6 values only in obese children with the G allele of the -866 G/A polymorphism.

Interleukin1beta genetic polymorphisms interact with polyunsaturated fatty acids to modulate risk of the metabolic syndrome

Chronic inflammation has been identified as an important component of the metabolic syndrome (MetS). Therefore, environmental and genetic factors contributing to the variation of inflammatory responses could affect individuals' susceptibility to MetS. We investigated the association between common IL1beta genetic polymorphisms, inflammation, and the MetS, and the modulation of diet-related variables (i.e., erythrocyte membrane fatty acid composition) in a white U.S. population. IL1beta single nucleotide polymorphisms (SNP) (-1473G > C, -511G > A, -31T > C, 3966C > T, 6054G > A), clinical and biochemical measurements were characterized in a total of 1120 subjects (540 males and 580 females) participating in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) Study. The 6054 G > A SNP was significantly associated with plasma C-reactive protein (P = 0.054), adiponectin (P = 0.021), and the prevalence of MetS (P = 0.004). Moreover, there was a significant interaction between the 6054G > A SNP and erythrocyte membrane (n-3) PUFA (P = 0.019). Among subjects with low (n-3) PUFA content (below the median), the 6054 G allele was associated with increased risk of the MetS (OR = 3.29, 95%CI = 1.49-7.26 for GG and OR = 1.95, 95%CI = 0.85-4.46 for GA, P < 0.001) compared with the AA genotype, but there were no significant genotype associations among subjects with high (n-3) PUFA content (above the median). Further analyses supported a significant haplotype global effect on the MetS (P = 0.017) among subjects with low (n-3) PUFA content. These results suggested that IL1beta genetic variants were associated with measures of chronic inflammation and the MetS risk, and that genetic influences were more evident among subjects with low (n-3) PUFA intake.

Dietary supplementation of obese children with 1000 mg alpha-linolenic acid per day: a placebo-controlled double blind study

Az omega-3 zsírsav fogyasztásának növelése kedvező hatású lehet a fokozott cardiovascularis kockázatú személyek, köztük az elhízottak számára. A kedvező hatások létrejöttének feltétele az omega-3 zsírsavaknak a szervezet plazmalipideibe történő beépülése, azonban a gyermekkorban ehhez szükséges szupplementációs dózisra vonatkozóan igen kevés adat áll rendelkezésre. A jelen vizsgálatunk célja napi 1000 mg alfa-linolénsavval kiegészített étrend a plazmalipidek zsírsavösszetételére kifejtett hatásának vizsgálata volt elhízott gyermekekben. Személyek és módszerek: Ebben a placebóval kontrollált, keresztező önkontrollos, 2 × 6 hétig tartó vizsgálatban a részt vevő 9 elhízott gyermek (életkor: 13,1 [±2,5] év, testtömegindex: 31,2 [±6,2] kg/m 2 , medián [IQR]) étrendjébe speciális takarmánnyal etetett tyúkoktól származó napi 1 tojást és 50 g csirkehúst építettünk be, amivel napi 1000 mg alfa-linolénsav bevitelét tudtuk biztosítani. A plazmalipidek zsírsavösszetételét nagy felbontóképességű kapilláris gáz-folyadék kromatográfiával határoztuk meg. Eredmények: Az alfa-linolénsav-értékek emelkedő tendenciája volt megfigyelhető az alfa-linolénsavval történő szupplementációt követően a foszfolipid-, a triacil-glicerin- és a szterol-észter-frakcióban egyaránt, azonban egyik frakcióban sem volt a változás szignifikáns. A nem észterifikált zsírsavfrakcióban az alfa-linolénsav értékei szignifikánsan emelkedtek (0,11 [0,08] szemben 0,14 [0,20], tömeg%, p < 0,05), jelezve az alfa-linolénsav plazmalipidekben történő feldúsulásának a kezdetét. Következtetés: Az elhízott gyermekekben az étrend 6 héten keresztül napi 1000 mg alfa-linolénsavval történő kiegészítése csak a plazma nem észterifikált zsírsavaiban növelte szignifikánsan az omega-3 zsírsavak arányát, az észterifikált frakciókban nem volt szignifikáns hatás. Elhízott gyermekekben az omega-3-zsírsavellátottság befolyásolásához az alfa-linolénsav-szupplementáció dózisának 1 g/nap fölé történő növelése tűnik szükségesnek.

Characteristics of obese children with low content of arachidonic acid in plasma lipids

BACKGROUND

Although there have been many studies on the relationship between obesity and long-chain polyunsaturated fatty acid (LCPUFA), the results and their interpretation are controversial, especially in children. Arachidonic acid (AA), the product of n-6 LCPUFA, is reported to be related to insulin resistance. The purpose of the present paper was to investigate the LCPUFA profile in obese children and mechanisms that contribute to reduced AA content.

METHOD

An age- and sex-matched control study was performed. The study subjects were 59 obese children (mean age, 11.8 years) and 53 healthy non-obese children (mean age, 12.5 years). The study parameters included anthropometric measurements, serum lipids, leptin and fatty acid composition in plasma.

RESULTS

Plasma fatty acids in obese children had lower linoleic acid (P < 0.0001) and higher dihomo-gamma-linolenic acid (P = 0.0004) than those in non-obese children. In all subjects combined, delta-6 desaturase (D6D) index (ratios of [C 18:3n-6+C 20:2n-6]/C 20:4n-6 or C 20:4n-6/C 18: 2n-6) correlated with leptin (P < 0.0001). There was no significant difference in AA content between obese and non-obese. However, the AA content was low (<mean - 1SD in controls) in 27.1% of obese children, in whom D6D index was not elevated in spite of high insulin concentration.

CONCLUSION

Obese children had changes in plasma LCPUFA profile that indicate upregulation of n-6 LCPUFA metabolism, probably caused by activated D6D activity to compensate AA demand. Heterogeneity of AA content in obese children depends on D6D and delta-5-desaturase activity, which may reflect insulin sensitivity.

Adipose tissue arachidonic acid and the metabolic syndrome in Costa Rican adults

BACKGROUND & AIMS

Arachidonic acid, a precursor to a series of inflammatory mediators, may contribute to the development of insulin resistance. We examined the association between adipose tissue arachidonic acid and the metabolic syndrome in Costa Rica, a country in which the metabolic syndrome is highly prevalent.

METHODS

The 484 study participants each provided a fasting blood sample and an adipose tissue biopsy that was analyzed for fatty acid composition. Criteria for the metabolic syndrome were those established in the Third Report of the National Cholesterol Education Program Expert Panel. The data were analyzed by multivariate logistic regression.

RESULTS

Subjects with greater adipose tissue arachidonic acid content had an increasing risk of the metabolic syndrome across quintiles: odds ratio (95% confidence interval), 1.00; 1.51 (0.78-2.91); 2.40 (1.26-4.55); 3.50 (1.84-6.66); and 6.01 (3.11-11.61); test for trend, P<0.0001, after adjustment for age, gender and area of residence. Further adjustment for metabolic risk factors, including adipose fatty acids and body mass index, did not significantly modify the result. Adipose tissue arachidonic acid was also independently associated with abdominal obesity, hypertriglyceridemia, elevated fasting glucose, and high blood pressure.

CONCLUSIONS

This study identifies arachidonic acid as an important independent marker of metabolic dysregulation. A better understanding of the role of this fatty acid in the pathogenesis of the metabolic syndrome is warranted.

Arachidonic acid content in adipose tissue is associated with insulin resistance in healthy children

BACKGROUND

The fatty acid composition of membrane structural lipids, which is partly dependent on dietary intake, is associated with insulin action.

AIM

To examine the association between fatty acid composition of adipose tissue and skeletal muscle phospholipids with insulin resistance markers in a healthy pediatric population.

METHODS

Using a cross-sectional design, we studied 83 healthy children divided into 3 groups, ages 2 to 5, 6 to 10 and more than 10 years.

MEASUREMENTS

Fatty acid composition of adipose tissue triacylglycerols and skeletal muscle phospholipids, plasma lipid profile and fasting plasma levels of glucose and insulin were measured.

RESULTS

There was a linear increase of insulinemia, glycemia and homeostasis adipose tissue model assessment (HOMA) index throughout the pediatric age range. Linoleic acid proportion in skeletal muscle and arachidonic acid proportion in adipose tissue also increased significantly with age. An age-independent positive correlation between insulinemia or HOMA index and arachidonic acid content in adipose tissue triacylglycerols (r = 0.47, P < 0.001) was found. An age-dependent negative correlation was present between insulinemia or HOMA index and oleic acid content in skeletal muscle phospholipids (r = -0.30, P = 0.03 and r = -0.28, P < 0.04, respectively). Trans fatty acids content did not correlate with any marker of insulin resistance.

CONCLUSION

Healthy children present a prepubertal increase of insulin resistance, which is significantly correlated with arachidonic acid content in adipose tissue.

Serum phospholipid fatty acids, adipose tissue, and metabolic markers in obese adolescents

OBJECTIVE

Fatty acid (FA) composition has a role in adipogenesis. The objective was to study serum phospholipid (PL) FAs in adolescents and their relation to abdominal adipose tissue (AT) compartments and metabolic markers.

RESEARCH METHODS AND PROCEDURES

Abdominal AT was measured by magnetic resonance imaging and FA pattern was determined in serum PL of 10 obese adolescents (5 females), median age 12.0 years (range, 10.4 to 16.4) and BMI 30.7 (26.8 to 40.4), and 15 lean control subjects (9 females), median age 12.6 years (range, 11.3 to 15.4), and BMI 19.5 (17.1 to 23.4).

RESULTS

Obese adolescents had relatively higher levels of saturated FA (SFA) and nervonic acid compared with controls. Serum PL concentration of n-3 polyunsaturated fatty acids (PUFA) was lower in the obese vs. lean females (p = 0.01), including docosahexaenoic acid (DHA) (p = 0.01). The ratios of arachidonic acid to DHA and total n-6/n-3 FA were increased in obese children (p = 0.02 and 0.01, respectively). n-3 PUFAs were inversely correlated to all subcutaneous AT compartments except visceral AT. The homeostasis model assessment index of beta-cell function related inversely to DHA concentration (p = 0.03). All changes were more marked in the females.

DISCUSSION

Serum FA pattern in obese adolescents differed significantly from that in age-matched lean controls, reflecting a decrease in n-3 PUFA, especially DHA, and an increase in SFA. The subcutaneous AT, but not visceral AT, correlated to the changes in PUFA and SFA, suggesting an abnormal essential FA metabolism in obese adolescents.

Plasma long-chain fatty acids and the degree of obesity in Italian children

AIM

To examine whether the plasma levels of long-chain polyunsaturated fatty acids (LC-PUFAs) are associated with the degree of obesity in children.

METHODS

Sixty-seven normolipidaemic obese children, aged 8-12 y, and 67 age- and sex-matched normal-weight children were included in the study. Obesity was defined in accordance with the International Obesity Task Force. BMI z-scores were calculated. Fasting blood samples were analysed for insulin, glucose, lipid profile and fatty acid (FA) levels (expressed as % total FA). Insulin resistance was estimated by homeostatic model assessment (HOMA).

RESULTS

Compared with normal-weight children, obese children exhibited lower mean plasma total PUFA (37.8% vs 39.7%), omega-6 PUFAs (35.0% vs 36.8%) and C22:6omega-3-to-C18:3omega-3 ratio (5.52 vs 7.61), and higher total monounsaturated FA (26.6% vs 25.0%), C18:3omega-3 (0.28% vs 0.25%) and C20:5omega-3 (0.45% vs 0.39%). In obese children, the BMI z-score was negatively related to plasma PUFA, omega-3 PUFAs, C22:6omega-3, and the C22:6omega-3-to-C20:6omega-6 and C22:6omega-3-to-C18:3omega-3 ratios, and positively with total saturated FA and C20:3omega-9.

CONCLUSION

In obese children, plasma LC-PUFA profile may be associated with the degree of obesity.

Thr-encoding Allele Homozygosity at Codon 54 of FABP 2 Gene May be Associated with Impaired Delta 6 Desatruase Activity and Reduced Plasma Arachidonic Acid in Obese Children

BACKGROUND

Alanine-for-threonine substitution at codon 54 (A54T polymorphism) in the fatty acid-binding protein 2 gene (FABP2) has been associated with hypertriglyceridemia and insulin resistance. Impairment in the activity of delta 6 and 5 desaturases is also supposed to be a factor predisposing the development of insulin resistance syndrome.

AIM

We investigated the relationship between A54T polymorphism in FABP2 and the impairment of long-chain polyunsaturated fatty acid metabolism in obese children.

METHODS

Thirty-two obese children participated. During the study, the children continued their habitual diet, which was documented in a 3-day food record using household measures. Anthropometry was performed, and serum lipid and fatty acid composition in plasma were analyzed. The polymorphism of codon 54 in the FABP 2 gene was analyzed.

RESULTS

The allele frequency was 0.66 and 0.34 for Ala54 and Thr54, respectively. There were no significant differences in age, body mass index, fasting serum glucose, insulin or serum lipoproteins among the three polymorphism groups. These were also no significant differences in the intake of energy, the percentage of energy nutrients or in the dietary lipid composition. The content of arachidonic acid (AA) in plasma was lowest in Thr/Thr54 (p < 0.05). The indices of delta-6 desaturase (D6D) activity in Thr/Thr54 were significantly lower than in Thr/Ala54 or Ala/Ala54 (p < 0.05, p < 0.01, respectively).

CONCLUSIONS

In obese children, Thr/Thr54 of the FABP 2 gene is associated with impaired activation of D6D and reduced AA content. The results in the LCPUFA profile suggest that Thr/Thr54 may predispose the to development of insulin resistance.

Plasma fatty acid composition is associated with the metabolic syndrome and low-grade inflammation in overweight adolescents

BACKGROUND

Together with adiposity, plasma fatty acid (FA) composition can modulate the development of the metabolic syndrome (MS).

OBJECTIVE

Our aim was to investigate the relations of FA composition in plasma phospholipids and cholesterol esters (CEs) with weight status, MS, and inflammation in adolescents.

DESIGN

Plasma FA composition was measured by gas-liquid chromatography in 120 (60 normal-weight and 60 overweight) 12-y-old adolescents. We also measured the presence of MS, insulin resistance with the homeostasis model assessment, and interleukin 6 and C-reactive protein concentrations in the adolescents.

RESULTS

MS was present in 25% of the overweight adolescents but in none of the normal-weight adolescents. Compared with overweight adolescents, normal-weight adolescents had lower saturated FAs (SFAs) in both phospholipids (P < 0.001) and CEs (P < 0.01) and higher docosahexaenoic acid in phospholipids (P < 0.001). In overweight subjects, FA composition was associated with MS features independent of body fat. The odds ratios of MS for a 0.1 increase in the ratio of polyunsaturated FAs (PUFA) to SFAs (PUFA:SFA) were 0.91 in phospholipids (P = 0.03) and 0.90 in CEs (P = 0.06). In phospholipids, PUFA:SFA and linoleic acid were associated positively with HDL cholesterol (P < 0.01 for both). PUFA:SFA in phospholipids and CEs were associated inversely with interleukin 6 (P < 0.05 for both). Eicosapentaenoic acid in phospholipids (P = 0.06) and CEs (P < 0.05) and linolenic acid in CEs (P < 0.05) were inversely related to C-reactive protein. These relations remained significant after adjustment for the waist-to-hip ratio. No significant relation between FA composition and the homeostasis model assessment was observed.

CONCLUSIONS

Plasma FA composition is associated with weight status in healthy adolescents. High intake of long-chain PUFAs, especially n-3 PUFAs, may protect obese subjects against MS and low-grade inflammation as early as adolescence.

A mathematical model of fatty acid metabolism and VLDL assembly in human liver

The lipid composition of very-low-density lipoprotein (VLDL) in plasma is crucial for human health. A pre-requisite for the alteration of VLDL composition is a co-ordinated understanding of the complex interactions in VLDL assembly. In order to determine the potential effects of changes in substrate availability on VLDL lipid composition, we constructed, parameterized and evaluated a mechanistic mathematical model of the biosynthesis of triglycerides, phospholipids, and cholesterol esters and the assembly of VLDL in human hepatocytes. Using published data on human liver metabolism, the model was also used to provide insight into the complex process of lipid metabolism and to estimate the affinities of different liver enzymes for different fatty acids (FA). For example, we found that Delta6-desaturase is 19 times more selective for C18:3n-3 than C18:2n-6, stearoyl-CoA-desaturase is 2.7 times more selective for C18:0 than C16:0, Delta5-desaturase desaturates C20:4n-3 preferentially over C20:3n-6 and FA elongase preferentially elongates C18:3n-6. The model was also used to predict the plasma free fatty acid (FFA) composition required to generate a prescribed change in plasma lipoprotein FA composition. Furthermore, the model was tested against a published human feeding trial that investigated the effect of changes in dietary FA composition on human plasma lipid FA composition. The model is a useful tool for predicting the effect of changes in plasma FFA composition on plasma lipoprotein lipid FA composition.

Polyunsaturated fatty acids in plasma lipids of diabetic children during and after diabetic ketoacidosis

BACKGROUND AND AIM

Previously we reported significantly higher plasma values of the essential fatty acids but significantly lower values of their longer-chain metabolites in diabetic children than in healthy controls. Here, we report data on the acute effect of diabetic ketoacidosis (DKA) on the fatty acid composition of plasma lipids.

METHODS

Diabetic children (n=9; age: 16.1 [3.3] y; duration of diabetes: 5.0 [5.3.] y; daily insulin dose: 0.87 [0.66] unit/kg body weight/d; glycated haemoglobin: 13.4 [2.8] %; median [IQR]) were investigated at admission for DKA (during DKA) and at the end of the treatment of DKA (after DKA). Fatty acid composition of plasma lipid classes was determined by high-resolution capillary gas-liquid chromatography.

RESULTS

Blood glucose (27.0 [8.5] vs 6.5 [1.6] mmol/l), pH (7.28 [0.35] vs 7.36 [0.06]) and base excess (-8.9 [15.1] vs -2.2 [6.3] mmol/l) were grossly abnormal during but not after DKA. Values of linoleic acid were significantly lower after than during DKA (non-esterifed fatty acids (NEFA): 15.55 [1.47] vs 12.27 [5.74] % wt/wt; triacylglycerols (TG): 20.84 [9.23] vs 17.40 [5.78]; p<0.05). In contrast, values of gamma-linolenic acid (NEFA: 0.87 [0.54] vs 2.34 [1.85]; p<0.05) and arachidonic acid (TG: 1.37 [0.71] vs 1.74 [0.57]; p<0.05) were significantly lower during than after DKA. The product/substrate ratios for delta-6 desaturation were significantly lower during than after DKA.

CONCLUSION

Successful treatment of diabetic ketoacidosis is associated with a significant increase of long-chain polyunsaturated fatty acid values in blood plasma in diabetic children. This observation suggests that disturbances of essential fatty acid metabolism in diabetic children are related not only to diet but to hypoinsulinaemia as well.

Obese type 2 diabetics and obese patients have comparable plasma phospholipid fatty acid compositions deviating from that of healthy individuals

There exist controversial reports regarding the differences in phospholipid fatty acids in type 2 diabetic and obese patients as compared to controls. The study was aimed at assessing the combined effect of type 2 diabetes and obesity on the fatty acid composition of plasma phospholipids. The experimental group consisted of 23 Belgian obese type 2 diabetics on Metformin. Two control groups were used: healthy lean and obese individuals in the same BMI range as the diabetics. Plasma phospholipids were isolated and their fatty acids and vinyl ether moieties were determined. Significance was set at P < 0.01. Plasma phospholipid fatty acids and plasmalogen-derived dimethyl acetals in diabetics deviated in many respects from these of lean controls but were not significantly different from those of obese non-diabetic patients. Therefore, the deviations of the fatty acid pattern of plasma phospholipids in type 2 diabetes may be attributed to obesity rather than to diabetes itself.

Dietary habits and plasma fatty acids levels in a population of Italian children: is there any relationship?

The relationships between dietary habits and the blood fatty acid (FA) profile have been poorly explored, particularly in children. Aim of the present investigation was to look at the associations between dietary habits and the plasma pattern of FA in a school-age population. In 105 healthy 8-years old children, the nutritional habits have been evaluated by means of a Food Frequency Questionnaire and a 24-h recall. FA analyses (expressed as FA%) were performed by means of capillary gas chromatography.

STATISTICS

non-parametric tests. The children with high pasta and low red meat consumption (n = 9), compared to those with either medium or low pasta and either high or medium red meat consumption (n = 96), showed lower levels of total saturated (29% vs. 35%, P = 0.001) and higher levels of total monounsaturated (30% vs. 24%, P = 0.04) FA in plasma. They also showed lower levels of LDL cholesterol (90 vs. 109 mg/dl, P = 0.08) and fasting insulin (4.0 vs. 6.3 microU/ml, P = 0.04) in blood. A high consumption of pasta coupled with a low intake of red meat may be marker of a food behaviour and/or lifestyle associated with a more favourable pattern of circulating FA and hematochemical metabolic markers.

Association of adipose tissue arachidonic acid content with BMI and overweight status in children from Cyprus and Crete

The relationships between n-3 and n-6 fatty acids in subcutaneous fat, BMI and overweight status were investigated in eighty-eight children from Crete and Cyprus. Overweight status, BMI and serum lipid levels were similar in children at both locations, but Cretan children had higher levels of total MUFA than Cypriot children (62.2 (sd 2.8) v. 52.2 (sd 2.8) % area, respectively, P<0.001) and consequently Cypriot children had higher levels of total saturated, polyunsaturated, trans, n-3 and n-6 fatty acids. Cypriot children had also higher levels of individual n-3 and n-6 fatty acids, specifically linoleic, alpha-linolenic and dihomo-gamma-linolenic acids. The variance of BMI was better explained (38.2 %) by adipose tissue arachidonic acid content than any other n-3 and n-6 fatty acids. Mean levels of arachidonic acid, dihomo-gamma-linolenic acid and docosahexaenoic acid were higher in overweight and obese subjects. All obese subjects fell in the 4th quartile of arachidonic acid levels, whereas 88.9 % of overweight subjects fell in the 3rd and 4th quartile of arachidonic acid. These results indicate positive associations between adipose tissue arachidonic acid and BMI and overweight status. Further research could clarify whether this association is causal.

Short term effects of dietary medium-chain fatty acids and n-3 long-chain polyunsaturated fatty acids on the fat metabolism of healthy volunteers

BACKGROUND

The amount and quality of dietary fatty acids can modulate the fat metabolism.

OBJECTIVE

This dietary intervention is based on the different metabolic pathways of long-chain saturated fatty acids (LCFA), which are mostly stored in adipocytic triacylglycerols, medium-chain fatty acids (MCFA) which are preferentially available for hepatic mitochondrial beta-oxidation and n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) suggested to modulate fat oxidation and storage by stimulating the peroxisomal beta-oxidation. Combined dietary MCFA and n-3 LCPUFA without LCFA may synergistically stimulate fatty acid oxidation resulting in blood lipid clearance and LCFA release from adipocytes.

DESIGN

In a short term, parallel, randomized, double-blind trial effects on the fatty acid metabolism of 10 healthy volunteers (Body Mass Index 25-30) of a formula containing 72% MCFA and 22% n-3 LCPUFA without LCFA (intake: 1.500 kcal/day; fat: 55.5% of energy) were measured in comparison to an isoenergetic formula with equal fat amount and LCFA dominated lipid profile.

RESULTS

The plasma triacylglycerol (p < 0.1) and cholesterol (p < 0.05) content decreased in the test group. The n-3/n-6 LCPUFA (> or = C 20) ratio increased (p < 0.0001) after 4 days treatment. The LCFA content was similar in both groups despite missing LCFA in the test formula indicating LCFA release from adipocytes into the plasma. Both groups significantly reduced body weight considerably 4 kg (p < 0.01) and fat mass up to 50% of weight loss (p < 0.05).

CONCLUSION

Combined dietary 72% MCFA and 22% n-3 LCPUFA without LCFA stimulate the fatty acid oxidation and release from adipocytes without affecting any safety parameters measured.

Insulin resistance syndrome in children : pathophysiology and potential management strategies

The simultaneous presence of various cardiovascular risk factors in the same individual is not rare, even in the pediatric age group. The clustering of risk factors can be termed insulin resistance syndrome (IRS) because of the putative central role of tissue insulin insensitivity in the background of the inter-related metabolic disturbances. Fasting hyperinsulinemia, impaired glucose tolerance, dyslipidemia, and hypertension are considered to represent the basic abnormalities of IRS. The most prevalent related disturbances are increased plasma levels of plasminogen activator inhibitor-1, fibrinogen, uric acid, homocysteine, and C-reactive protein, as well as visceral adiposity, microalbuminuria, disturbed essential fatty acid metabolism, low availability of lipid-soluble antioxidant vitamins, and enhanced expression of tumor necrosis factor-alpha in adipose tissues. Certain genetic abnormalities have been associated with IRS, but explain only a small part of the variability in insulin resistance. The exact prevalence of IRS in children remains to be defined; it was found to be 9% in one survey among children with obesity seeking medical attention. Modification of lifestyle, i.e. reduction of energy intake and enhancement of physical activity, are unquestionable prerequisites for long-term success in the management of IRS. In at least two randomized controlled studies, metformin proved to be clinically effective in increasing insulin sensitivity in hyperinsulinemic, nondiabetic adolescents. Thiazolidinediones have been successfully tested for the treatment of insulin resistance in adults, but not in children as yet. Prevention of the development of IRS in children is obviously of great significance for the health status of the community. However, the efficacy of various preventive approaches should be investigated further in carefully designed controlled trials.