Dolores Parra

A diet rich in long chain omega-3 fatty acids modulates satiety in overweight and obese volunteers during weight loss.

Long chain omega-3 fatty acids (LC n-3 FA) are considered nutritional factors with a potential to modulate food intake. Thus, the aim of the current study was to determine whether appetite could be affected by LC n-3 FA when included in a calorie-restricted diet to treat overweight or obesity. Appetite was explored in volunteers (31+/-5 years; BMI: 28.3+/-1.5 kg/m(2)) during the last 2 weeks of an 8-week energy-restricted balanced diet (weight loss=-5.9+/-3.1%) providing either a low (<260 mg/day; n=112) or a high amount (>1300 mg/day; n=121) of LC n-3 FA. Erythrocyte membrane fatty acids were measured to detect diet-related changes in fatty acids and a validated visual analogue scale (VAS) was used to measure hunger sensations directly after and 2h after a test dinner. The LC n-3 FA content in erythrocyte membrane was lower in the low LC n-3 FA group (10.5+/-2.5% vs. 12.5+/-2.6%; p<0.001) after the intervention. The VAS assessment revealed lower hunger sensations in the high LC n-3 FA group immediately after the test dinner (fullness: p=0.045) and after 120 min (fullness: p=0.008; hunger: p=0.039). Correlation analysis showed a positive relation between n-3 FA/n-6 FA ratio in erythrocyte membrane and fullness 2h postprandial (r=0.139; p=0.032). In conclusion, LC n-3 FA intake modulates postprandial satiety in overweight and obese volunteers during weight loss. Further research is needed to investigate whether LC n-3 FA improve compliance to the nutritional treatment of overweight and obesity as well as weight loss maintenance.

Differential Expression of Oxidative Stress and Inflammation Related Genes in Peripheral Blood Mononuclear Cells in Response to a Low-Calorie Diet: A Nutrigenomics Study

Nutrigenomics is a new application of omics technologies in nutritional science. Nutrigenomics aims to identify molecular markers of diet-related diseases and mechanisms of interindividual variability in response to food. The aim of this study was to evaluate peripheral blood mononuclear cells (PBMC) as a model system and readily available source of RNA to discern gene expression signatures in relation to personalized therapy of obesity. PBMC were collected from obese men before and after an 8-week low-calorie diet (LCD) to lose weight. Changes in gene expression before and after the LCD were initially screened using a DNA-microarray platform and validated by qRT-PCR. Global gene expression analysis identified 385 differentially expressed transcripts after the LCD. Further analyses showed a decrease in some specific oxidative stress and inflammation genes. Interestingly, expression of these genes was directly related to body weight, while a lower IL8 gene expression was associated with higher fat mass decrease. Collectively, these observations suggest that PBMCs are a suitable RNA source and model system to perform nutrigenomics studies related to obesity and development of personalized dietary treatments. IL8 gene expression warrant further research as a putative novel biomarker of changes in body fat percentage in response to an LCD.

Energy-restricted diets based on a distinct food selection affecting the glycemic index induce different weight loss and oxidative response

BACKGROUND & AIMS Low glycemic index (GI) based diets could influence the accompanying physiological adaptations to energy restriction in the treatment of obesity. It was aimed to investigate the effects of two energy-restricted diets with different food distribution and GI values on weight loss and energy metabolism in the nutritional treatment of obesity. SUBJECTS AND METHODS Participants (n=32; BMI: 32.5+/-4.3 kg/m(2)) were randomly assigned to follow two energy-restricted diets with higher-GI or lower-GI for 8 weeks. The energy restriction was -30% in relation to energy expenditure. Anthropometry, energy expenditure and mitochondrial oxidation were assessed at baseline and at the endpoint of the intervention. Body weight was also measured one year after the treatment. The work was approved by the ethical committees of the University of Navarra (54/2006). RESULTS Volunteers consuming the lower-GI diet showed a significantly higher weight loss than their counterparts (-5.3+/-2.6% vs -7.5+/-2.9%; p=0.032), although the decrease in resting energy expenditure (REE) was similar between groups (p=0.783). Mitochondrial oxidation was significantly affected by the type of diet (p=0.001), being activated after the lower-GI treatment (p=0.022). Interestingly, one year after the nutritional intervention weight regain was only statistically significant in the higher-GI group (p=0.033). CONCLUSIONS Lower-GI energy-restricted diets achieved through a specific differential food selection can improve the energy adaptations during obesity treatment, favouring weight loss and probably weight maintenance compared with higher-GI hypocaloric diets.

A hypocaloric diet enriched in legumes specifically mitigates lipid peroxidation in obese subjects

Legume intake could specifically protect against lipid peroxidation in addition to the effects associated to weight loss when included in hypocaloric diets. Thus, 30 obese subjects (age: 36 ± 8 years and BMI: 32.0 ± 5.3 kg/m2) were nutritionally treated by a 8-week energy restriction ( − 30% energy expenditure) with a legume enriched diet (4 days/week servings, ) or without legumes (control diet (CD), ). Body weight, circulating cholesterol, oxidized LDL (ox-LDL), malondialdehyde (MDA) and urinary 8-isoprostane F2α (8-iso-PGF2α) were measured at baseline and at endpoint. After the nutritional intervention, all obese subjects lost weight, specially those individuals who followed the legumes-enriched diet as compared to the CD ( − 7.7 ± 3 vs. − 5.3 ± 2.7%; p = 0.023), which was accompanied by marked decreases in total cholesterol levels (p < 0.001) and statistically significant diet-related reductions on plasma ox-LDL, plasma MDA and urinary 8-iso-PGF2α output. Therefore, a balanced diet with moderate caloric restriction including 4 day/week legume servings empowered the oxidative stress improvement related to weight loss through a reduction in lipid peroxidation as compared to a control hypocaloric diet.

Sirtuin gene expression in human mononuclear cells is modulated by caloric restriction

Background  Sirtuins may provide novel targets for treating some diseases associated with oxidative stress, such as obesity and its comorbidities. However, there are a few in vivo studies in humans about the potential role of sirtuins as therapeutic targets among obese patients undergoing caloric restriction. Therefore, the aim of this study was to assess if the gene expression of sirtuins is modulated in peripheral blood mononuclear cells (PBMC) by a hypocaloric diet devised to lose weight in humans.

Legume-, Fish-, or High-Protein-Based Hypocaloric Diets: Effects on Weight Loss and Mitochondrial Oxidation in Obese Men

The nutritional composition of dietary intake could produce specific effects on metabolic variables such as mitochondrial oxidation, whose understanding could contribute to apply more individualized weight-lowering strategies. This study assessed the effects of four hypocaloric diets with high protein content or different food distribution on metabolic changes and mitochondrial oxidation accompanying weight loss. Thirty-five obese men (body mass index of 31.8 +/- 3.0 kg/m(2) and 38 +/- 7 years old) were randomly assigned to one of the four treatments (8 weeks): control diet (C-diet); legume diet (L-diet); fatty fish diet (FF-diet); or high-protein diet (HP-diet). Body composition, blood pressure, resting energy expenditure, mitochondrial oxidation, blood biomarkers, and dietary intake were assessed. The HP-diet and L-diet achieved the greater body weight reduction (-8.4 +/- 1.2% and -8.3 +/- 2.9%, respectively), as compared to the C-diet (-5.5 +/- 2.5%; P = .042). The high-density lipoprotein cholesterol concentrations were reduced in all dietary groups except for the FF-diet. Total and low-density lipoprotein cholesterol levels were significantly improved by the L-diet (P < .05), while the homeostatic model assessment index of insulin resistance value was significantly reduced in those men following the HP-diet. Mitochondrial oxidation was specifically activated by the HP-diet and L-diet at the end of the study. Interestingly, a lineal regression model explained about 25% (P = .029) of the mitochondrial oxidation variability as influenced by the diet changes once adjusted by resting energy expenditure. The specific consumption of legumes or high protein content within a hypocaloric diet could activate mitochondrial oxidation, which could involve additional benefits to those associated with the weight reduction.

Specific insulin sensitivity and leptin responses to a nutritional treatment of obesity via a combination of energy restriction and fatty fish intake

BACKGROUND Nutritional strategies to treat obesity often influence neuroendocrine factors related to body weight control. The present study aimed to investigate whether the inclusion of three fatty fish servings per week within a hypocaloric diet may have specific healthy effects on insulin and leptin functions. METHODS Thirty-two subjects (body mass index = 31.6 +/- 3.5 kg m(-2)) aged 36 +/- 7 years, were assigned to a control or fish-based energy-restricted diet over an 8-week period. Anthropometry, body composition, lipid profile, leptin and insulin values were measured at the start and at the end of the dietary intervention. RESULTS Both experimental diets resulted in a similar mean weight loss (control = 5.3 +/- 2.6% versus fish-based = 5.5 +/- 2.5%; P = 0.783). A significant reduction in insulin resistance, as determined by the homeostatic model assessment index (HOMA-IR = insulin x glucose/22.5), was observed after the fish-based intervention. The change in circulating leptin was higher in the fish-based diet compared to the control group. Sixteen percent of the variability in the change of adjusted-leptin could be explained (P = 0.034) by the HOMA index change and the type of diet. CONCLUSIONS Three servings a week of fatty fish included in an energy-restricted diet appears to be a valid strategy for specifically improving insulin sensitivity and leptin levels in obese subjects, which could involve a better body weight regulation after a nutritional intervention period.

A Nutrigenomic Inflammation-Related PBMC-Based Approach to Predict the Weight-Loss Regain in Obese Subjects

Background: Long-term maintenance of a dietary-induced weight loss continues to be a major health problem and warrants research on innovative approaches to understand weight stability. We investigated the role of the proinflammatory status on weight changes in obese subjects receiving a low-calorie diet (LCD) and during the subsequent 6-month weight maintenance period. Methods: Eighty-four subjects (age: 34.2 ± 0.53 years; body mass index, BMI: 30.4 ± 1.8 kg/m2) followed an 8-week LCD intervention and were contacted again 6 months later. Body composition, circulating proinflammatory markers [tumor necrosis factor (TNF)α, interleukin-6, C-reactive protein and leptin] and mRNA levels of inflammation-related genes [TNFα and nuclear factor (NF) κBtranscription subunits] in peripheral blood mononuclear cells (PBMC) were evaluated. Results: The 6-month weight regain was predicted by high concentrations of TNFα at LCD completion (OR = 4.21, p = 0.036) along with the baseline amount of fat mass (OR = 7.23, p = 0.029). In addition, baseline leptin concentrations (p = 0.028) as well as mRNA levels of TNFα and NFκB subunits were higher at the end of the dietary intervention (p < 0.05) in PBMC of subjects who regained ≥10% of the dietary-induced weight loss. Conclusions: These findings demonstrate a role for the proinflammatory state and body adiposity in the prediction of weight-loss regain. This relationship could contribute to the design of more personalized nutritional treatments in obese patients and favor the weight maintenance process.

Effects of two energy-restricted diets differing in the carbohydrate/protein ratio on weight loss and oxidative changes of obese men

Introduction Low-carbohydrate, high-protein diets are a current challenge in the nutritional treatment of obesity. Objective To compare the effect of a low-carbohydrate high-protein diet with a traditional hypocaloric diet on weight loss and mitochondrial oxidative metabolism. Subjects and methods Nineteen obese men (age 36±6 years; body mass index 34±2 kg/m2) were randomized to follow one of the two diets—control diet (15% protein; 30% lipids; 55% carbohydrates) or high-protein diet (30% protein; 30% lipids; 40% carbohydrates)—over an 8-week period. Anthropometry, biochemical variables, resting energy expenditure and mitochondrial oxidation were measured at the start and at the end of the intervention. Results The high-protein diet produced a greater weight loss (−8.3±1.2% versus −5.5±2.5%, P = 0.012) than the control diet. Interestingly, an activation in the mitochondrial oxidation was found in the high-protein-fed group. This stimulation was positively correlated with the final resting energy expenditure and negatively associated with the final fat mass content. Conclusion Low-carbohydrate high-protein diets could involve specific changes in mitochondrial oxidation that could be related to a higher weight loss.

Influence of n-3 polyunsaturated fatty acids on soluble cellular adhesion molecules as biomarkers of cardiovascular risk in young healthy subjects

BACKGROUND AND AIM Serum levels of soluble cellular adhesion molecules (CAMs) and blood lipid parameters have been used as markers of inflammatory processes associated with cardiovascular disease (CVD) events. The present study evaluated the effects of the intake of n-3 polyunsaturated fatty acids (PUFAs) in fish and fish oil within energy-restricted diets, on soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular adhesion molecule-1 (sVCAM-1). METHODS AND RESULTS Two hundred and seventy-five healthy European subjects aged between 20 and 40 years, were randomized to one of four hypocaloric dietary groups: control (sunflower oil capsules, no seafood), lean fish (3 x 150 g portions of cod/week), fatty fish (3 x 150 g portions of salmon/week), fish oil ((docosahexaenoic acid (DHA)+eicosapentaenoic acid (EPA) capsules, no seafood)). Diets rich in lean fish significantly decreased ICAM-1 levels, around 5% from baseline to endpoint (p<0.05), and had no effect on VCAM-1 levels. No significant differences were observed in sICAM-1 levels after the intervention with fatty fish or fish oils. On the other hand, these two seafood based diets were responsible for a significant increase of VCAM-1 levels [fatty fish; 16.1% and fish oil; 21.9%] respectively (p<0.05). CONCLUSIONS CAMs as inflammatory biomarkers in young and healthy subjects are not conclusive for the evaluation of CVD risk. Hypocaloric fish diets had a different effect on CAMs, being lean fish responsible for the highest decrease in ICAM-1. On the other hand, VCAM-1 results allow speculation that a low dose of n-3 PUFA may be anti-inflammatory contrarily to a high dose which can have a pro-inflammatory effect. CAMs mechanism is complex and affected by multiple factors such as lifestyle, gender, and n-3 dose and source.