Acute and repeated impact of sweeteners and sweetness enhancers in solid and semi-solid foods on appetite: protocol for a multicentre, cross-over, RCT in people with overweight/obesity - the SWEET Project.

INTRODUCTION: Intake of free sugars in European countries is high and attempts to reduce sugar intake have been mostly ineffective. Non-nutritive sweeteners and sweetness enhancers (S&SEs) can maintain sweet taste in the absence of energy, but little is known about the impact of acute and repeated consumption of S&SE in foods on appetite. This study aims to evaluate the effect of acute and repeated consumption of two individual S&SEs and two S&SE blends in semisolid and solid foods on appetite and related behavioural, metabolic and health outcomes. METHODS AND ANALYSIS: A work package of the SWEET Project; this study consists of five double-blind randomised cross-over trials which will be carried out at five sites across four European countries, aiming to have n=213. Five food matrices will be tested across three formulations (sucrose-sweetened control vs two reformulated products with S&SE blends and no added sugar). Participants (body mass index 25-35 kg/m2; aged 18-60 years) will consume each formulation for 14 days. The primary endpoint is composite appetite score (hunger, inverse of fullness, desire to eat and prospective food consumption) over a 3-hour postprandial incremental area under the curve during clinical investigation days on days 1 and 14. ETHICS AND DISSEMINATION: The trial has been approved by national ethical committees and will be conducted in accordance with the Declaration of Helsinki. Results will be published in international peer-reviewed open-access scientific journals. Research data from the trial will be deposited in an open-access online research data archive. TRIAL REGISTRATION NUMBER: NCT04633681.

Impact of COVID-19 Lockdown on Food Consumption and Behavior in France (COVISTRESS Study).

The COVID-19 pandemic and subsequent lockdowns modified work environments, lifestyles, and food consumption. Eating habits and mood changes in a French population during the first lockdown were examined using an online self-reported questionnaire with REDCap software through the COVISTRESS.ORG website. In 671 French participants, the main changes during lockdown were increased stress levels (64 [23; 86] vs. 3 [0; 18]) and sedentary behavior (7 [4; 9] vs. 5 [3; 8] hours per day), a deterioration in sleep quality (50 [27; 83] vs. 70 [48; 94]) and mood (50 [30; 76] vs. 78 [50; 92]), and less physical activity (2.0 [0.5; 5.0] vs. 3.5 [2.0; 6.0]). Mood was modified, with more anger (56 [39; 76] vs. 31 [16; 50]), more sadness (50 [34; 72] vs. 28 [16; 50]), more agitation (50 [25; 66] vs. 43 [20; 50]), and more boredom (32 [7; 60] vs. 14 [3; 29]). A total of 25% of the participants increased their consumption of alcoholic beverages, 29% their consumption of sugary foods, and 26% their consumption of cocktail snacks. A multiple-correspondence analysis highlights four different profiles according to changes in eating habits, food consumption, lifestyle, and mood. In conclusion, eating habits and lifestyle changes during lockdown periods should be carefully monitored to promote healthy behaviors.

Five-Year Changes in Weight and Diabetes Status After Bariatric Surgery for Craniopharyngioma-Related Hypothalamic Obesity: a Case-Control Study.

PURPOSE: Craniopharyngiomas are tumors located in the hypothalamic region which leads to obesity in about 50% of cases. Long-term efficacy and safety of bariatric surgery are lacking in this peculiar population. The aim of this study is to determine the 5-year weight loss and resolution of type 2 diabetes (T2D) after bariatric surgery in patients operated on craniopharyngioma who had developed hypothalamic obesity. MATERIALS AND METHODS: This is a multicenter french retrospective case-control study. Subjects with craniopharyngioma (n = 23) who underwent sleeve gastrectomy (SG) (n = 9) or Roux-en-Y gastric bypass (RYGB) (n = 14) (median age 35 years [25;43] and BMI 44.2 kg/m2 [40.7; 51.0]; 8/23 with T2D) were individually matched to 2 subjects with common obesity for age, gender, preoperative body mass index, T2D, and type of surgery. RESULTS: TWL% after 1 and 5 years was lower in the craniopharyngioma group than in the control group: 23.1 [15.4; 31.1] (23/23) vs 31.4 [23.9; 35.3] at 1 year (p = 0.008) (46/46) and 17.8 [7.1; 21.9] (23/23) vs 26.2 [18.9; 33.9] at 5 years (p = 0.003) (46/46). After RYGB, TWL% was lower in the craniopharyngioma group compared to the control group (p < 0.001) and comparable after SG both at 1 and 5 years. No difference between the two groups was observed in T2D remission rate and in early and late adverse events. No hormonal deficiency-related acute disease was reported. CONCLUSIONS: Bariatric surgery induced a significant weight loss in the craniopharyngioma group at 1 and 5 years, but less than in common obesity. SG may be more effective than RYGB but this remains to be demonstrated in a larger cohort.

Chitin-glucan supplementation improved postprandial metabolism and altered gut microbiota in subjects at cardiometabolic risk in a randomized trial.

Chitin-glucan (CG), an insoluble dietary fiber, has been shown to improve cardiometabolic disorders associated with obesity in mice. Its effects in healthy subjects has recently been studied, revealing its interaction with the gut microbiota. In this double-blind, randomized, cross-over, twice 3-week exploratory study, we investigated the impacts of CG on the cardiometabolic profile and gut microbiota composition and functions in 15 subjects at cardiometabolic risk. They consumed as a supplement 4.5 g of CG daily or maltodextrin as control. Before and after interventions, fasting and postprandial metabolic parameters and exhaled gases (hydrogen [H2] and methane [CH4]) were evaluated. Gut microbiota composition (16S rRNA gene sequencing analysis), fecal concentrations of bile acids, long- and short-chain fatty acids (LCFA, SCFA), zonulin, calprotectin and lipopolysaccharide binding protein (LBP) were analyzed. Compared to control, CG supplementation increased exhaled H2 following an enriched-fiber breakfast ingestion and decreased postprandial glycemia and triglyceridemia response to a standardized test meal challenge served at lunch. Of note, the decrease in postprandial glycemia was only observed in subjects with higher exhaled H2, assessed upon lactulose breath test performed at inclusion. CG decreased a family belonging to Actinobacteria phylum and increased 3 bacterial taxa: Erysipelotrichaceae UCG.003, Ruminococcaceae UCG.005 and Eubacterium ventriosum group. Fecal metabolites, inflammatory and intestinal permeability markers did not differ between groups. In conclusion, we showed that CG supplementation modified the gut microbiota composition and improved postprandial glycemic response, an early determinant of cardiometabolic risk. Our results also suggest breath H2 production as a non-invasive parameter of interest for predicting the effectiveness of dietary fiber intervention.

Guidelines on Standard and Therapeutic Diets for Adults in Hospitals by the French Association of Nutritionist Dieticians (AFDN) and the French Speaking Society of Clinical Nutrition and Metabolism (SFNCM).

AIM: Hospital food provision is subject to multiple constraints (meal production, organization, health safety, environmental respect) which influence the meal tray offered to the patient. Multiple diets can add complexity and contribute to non-consumption of the meal. To avoid undernutrition, it appeared necessary to propose guidelines for foods and diets in hospitals. METHODS: These guidelines were developed using the Delphi method, as recommended by the HAS (French Health Authority), based on a formal consensus of experts and led by a group of practitioners and dieticians from the AFDN (French Association of Nutritionist Dieticians) and SFNCM (French Society of Clinical Nutrition and Metabolism). RESULTS: Twenty-three recommendations were deemed appropriate and validated by a panel of 50 national experts, following three rounds of consultations, modifications and final strong agreement. These recommendations aim to define in adults: 1-harmonized vocabulary related to food and diets in hospitals; 2-quantitative and qualitative food propositions; 3-nutritional prescriptions; 4-diet patterns and patient adaptations; 5-streamlining of restrictions to reduce unnecessary diets and without scientific evidence; 6-emphasizing the place of an enriched and adapted diet for at-risk and malnourished patients. CONCLUSION: These guidelines will enable catering services and health-care teams to rationalize hospital food and therapeutic food prescriptions in order to focus on individual needs and tasty foods. All efforts should be made to create meals that follow these recommendations while promoting the taste quality of the dishes and their presentation such that the patient rediscovers the pleasure of eating in the hospital.

Development of a Repertoire and a Food Frequency Questionnaire for Estimating Dietary Fiber Intake Considering Prebiotics: Input from the FiberTAG Project.

Most official food composition tables and food questionnaires do not provide enough data to assess fermentable dietary fibers (DF) that can exert a health effect through their interaction with the gut microbiota. The aim of this study was to develop a database and a food frequency questionnaire (FFQ) allowing detailed DF intake estimation including prebiotic (oligo)saccharides. A repertoire of DF detailing total, soluble DF, insoluble DF and prebiotic (oligo)saccharides (inulin-type fructans, fructo-oligosaccharides and galacto-oligosaccharides) in food products consumed in Europe has been established. A 12 month FFQ was developed and submitted to 15 healthy volunteers from the FiberTAG study. Our data report a total DF intake of 38 g/day in the tested population. Fructan and fructo-oligosaccharides intake, linked notably to condiments (garlic and onions) ingestion, reached 5 and 2 g/day, respectively, galacto-oligosaccharides intake level being lower (1 g/day). We conclude that the FiberTAG repertoire and FFQ are major tools for the evaluation of the total amount of DF including prebiotics. Their use can be helpful in intervention or observational studies devoted to analyze microbiota-nutrient interactions in different pathological contexts, as well as to revisit DF intake recommendations as part of healthy lifestyles considering specific DF.

A series of severe neurologic complications after bariatric surgery in France: the NEUROBAR Study.

BACKGROUND: Neurologic complications after bariatric surgery are rare, but can have dramatic consequences. Little data are available on this topic. OBJECTIVES: The aim of the Neurologic complications after BARiatric surgery (NEUROBAR) study was to define, which factors (anthropometric, nutritional, surgical, etc.) were frequently associated with neurologic complications after bariatric surgery. SETTINGS: Data were collected by the French Centers of Obesity Care Management hosted in University Hospitals. METHODS: An online standardized questionnaire was designed and submitted to the 37 French Centers of Obesity Management. This questionnaire included items about patient characteristics, bariatric surgery, neurologic complications, nutritional status, and management. Patients were retrospectively included from January 2010 to November 2018. RESULTS: Thirteen centers included 38 patients (34 females and 4 males) with neurologic complications after bariatric surgery. The 2 main bariatric procedures were gastric bypass and sleeve gastrectomy. More than half of the patients with neurologic complications had a surgical complication after bariatric surgery (53%) and gastrointestinal symptoms, including vomiting (53%). Vitamin B deficiencies were frequent (74%) including at least 47% of cases with deficiency in Vitamin B1. CONCLUSION: Early identification of patients with surgical complications and gastrointestinal symptoms after bariatric surgery could help prevent neurologic complications related to nutritional deficiencies.

Postprandial Endotoxin Transporters LBP and sCD14 Differ in Obese vs. Overweight and Normal Weight Men during Fat-Rich Meal Digestion.

Circulating levels of lipopolysaccharide-binding protein (LBP) and soluble cluster of differentiation 14 (sCD14) are recognized as clinical markers of endotoxemia. In obese men, postprandial endotoxemia is modulated by the amount of fat ingested, being higher compared to normal-weight (NW) subjects. Relative variations of LBP/sCD14 ratio in response to overfeeding are also considered important in the inflammation set-up, as measured through IL-6 concentration. We tested the hypothesis that postprandial LBP and sCD14 circulating concentrations differed in obese vs. overweight and NW men after a fat-rich meal. We thus analyzed the postprandial kinetics of LBP and sCD14 in the context of two clinical trials involving postprandial tests in normal-, over-weight and obese men. In the first clinical trial eight NW and 8 obese men ingested breakfasts containing 10 vs. 40 g of fat. In the second clinical trial, 18 healthy men were overfed during 8 weeks. sCD14, LBP and Il-6 were measured in all subjects during 5 h after test meal. Obese men presented a higher fasting and postprandial LBP concentration in plasma than NW men regardless of fat load, while postprandial sCD14 was similar in both groups. Irrespective of the overfeeding treatment, we observed postprandial increase of sCD14 and decrease of LBP before and after OF. In obese individuals receiving a 10 g fat load, whereas IL-6 increased 5h after meal, LBP and sCD14 did not increase. No direct association between the postprandial kinetics of endotoxemia markers sCD14 and LBP and of inflammation in obese men was observed in this study.

OBEDIS Core Variables Project: European Expert Guidelines on a Minimal Core Set of Variables to Include in Randomized, Controlled Clinical Trials of Obesity Interventions.

Heterogeneity of interindividual and intraindividual responses to interventions is often observed in randomized, controlled trials for obesity. To address the global epidemic of obesity and move toward more personalized treatment regimens, the global research community must come together to identify factors that may drive these heterogeneous responses to interventions. This project, called OBEDIS (OBEsity Diverse Interventions Sharing - focusing on dietary and other interventions), provides a set of European guidelines for a minimal set of variables to include in future clinical trials on obesity, regardless of the specific endpoints. Broad adoption of these guidelines will enable researchers to harmonize and merge data from multiple intervention studies, allowing stratification of patients according to precise phenotyping criteria which are measured using standardized methods. In this way, studies across Europe may be pooled for better prediction of individuals' responses to an intervention for obesity - ultimately leading to better patient care and improved obesity outcomes.

Adipose Tissue Expansion by Overfeeding Healthy Men Alters Iron Gene Expression.

Context: Iron overload has been associated with greater adipose tissue (AT) depots. We retrospectively studied the potential interactions between iron and AT during an experimental overfeeding in participants without obesity. Methods: Twenty-six participants (mean body mass index ± SD, 24.7 ± 3.1 kg/m2) underwent a 56-day overfeeding (+760 kcal/d). Serum iron biomarkers (ELISA), subcutaneous AT (SAT) gene expression, and abdominal AT distribution assessed by MRI were analyzed at the beginning and the end of the intervention. Results: Before intervention: SAT mRNA expression of the iron transporter transferrin (Tf) was positively correlated with the expression of genes related to lipogenesis (lipin 1, ACSL1) and lipid storage (SCD). SAT expression of the ferritin light chain (FTL) gene, encoding ferritin (FT), an intracellular iron storage protein, was negatively correlated to SREBF1, a gene related to lipogenesis. Serum FT (mean, 92 ± 57 ng/mL) was negatively correlated with the expression of SAT genes linked to lipid storage (SCD, DGAT2) and to lipogenesis (SREBF1, ACSL1). After intervention: Overfeeding led to a 2.3 ± 1.3-kg weight gain. In parallel to increased expression of lipid storage-related genes (mitoNEET, SCD, DGAT2, SREBF1), SAT Tf, SLC40A1 (encoding ferroportin 1, a membrane iron export channel) and hephaestin mRNA levels increased, whereas SAT FTL mRNA decreased, suggesting increased AT iron requirement. Serum FT decreased to 67 ± 43 ng/mL. However, no significant associations between serum iron biomarkers and AT distribution or expansion were observed. Conclusion: In healthy men, iron metabolism gene expression in SAT is associated with lipid storage and lipogenesis genes expression and is modulated during a 56-day overfeeding diet.

Evidence-based practice within nutrition: what are the barriers for improving the evidence and how can they be dealt with?

BACKGROUND: Evidence-based clinical research poses special barriers in the field of nutrition. The present review summarises the main barriers to research in the field of nutrition that are not common to all randomised clinical trials or trials on rare diseases and highlights opportunities for improvements. METHODS: Systematic academic literature searches and internal European Clinical Research Infrastructure Network (ECRIN) communications during face-to-face meetings and telephone conferences from 2013 to 2017 within the context of the ECRIN Integrating Activity (ECRIN-IA) project. RESULTS: Many nutrients occur in multiple forms that differ in biological activity, and several factors can alter their bioavailability which raises barriers to their assessment. These include specific difficulties with blinding procedures, with assessments of dietary intake, and with selecting appropriate outcomes as patient-centred outcomes may occur decennia into the future. The methodologies and regulations for drug trials are, however, applicable to nutrition trials. CONCLUSIONS: Research on clinical nutrition should start by collecting clinical data systematically in databases and registries. Measurable patient-centred outcomes and appropriate study designs are needed. International cooperation and multistakeholder engagement are key for success.

Odd Chain Fatty Acids; New Insights of the Relationship Between the Gut Microbiota, Dietary Intake, Biosynthesis and Glucose Intolerance.

Recent findings have shown an inverse association between circulating C15:0/C17:0 fatty acids with disease risk, therefore, their origin needs to be determined to understanding their role in these pathologies. Through combinations of both animal and human intervention studies, we comprehensively investigated all possible contributions of these fatty acids from the gut-microbiota, the diet, and novel endogenous biosynthesis. Investigations included an intestinal germ-free study and a C15:0/C17:0 diet dose response study. Endogenous production was assessed through: a stearic acid infusion, phytol supplementation, and a Hacl1-/- mouse model. Two human dietary intervention studies were used to translate the results. Finally, a study comparing baseline C15:0/C17:0 with the prognosis of glucose intolerance. We found that circulating C15:0/C17:0 levels were not influenced by the gut-microbiota. The dose response study showed C15:0 had a linear response, however C17:0 was not directly correlated. The phytol supplementation only decreased C17:0. Stearic acid infusion only increased C17:0. Hacl1-/- only decreased C17:0. The glucose intolerance study showed only C17:0 correlated with prognosis. To summarise, circulating C15:0 and C17:0 are independently derived; C15:0 correlates directly with dietary intake, while C17:0 is substantially biosynthesized, therefore, they are not homologous in the aetiology of metabolic disease. Our findings emphasize the importance of the biosynthesis of C17:0 and recognizing its link with metabolic disease.

Modulation of the gut microbiota by nutrients with prebiotic and probiotic properties.

Experimental data in animals, but also observational studies in humans, suggest that the composition of the gut microbiota differs in obese vs. lean individuals, in patients with vs. without diabetes, or in patients presenting other diseases associated with obesity or nutritional disbalance, such as non-alcoholic fatty liver disease (NAFLD) or cardiovascular diseases. In this review, we describe how changes in the composition and/or activity of the gut microbiota by administration of nutrients with probiotic or prebiotic properties can modulate host gene expression and metabolism and thereby positively influence host adipose tissue development and related metabolic disorders.

Overfeeding increases postprandial endotoxemia in men: Inflammatory outcome may depend on LPS transporters LBP and sCD14.

SCOPE: Low-grade inflammation is a recognized hallmark of obesity. Endotoxins absorbed after high-fat meals have recently been implicated. Plasma lipopolysaccharides binding protein (LBP) and soluble cluster of differentiation 14 (sCD14) have also been suggested as clinical markers of endotoxemia. In mice, the ratio LBP/sCD14 has been associated with high fat diet induced inflammation. We tested the hypothesis that healthy subjects develop inflammation differently during weight gain according to changes of LBP/sCD14 ratio. METHODS AND RESULTS: Eighteen healthy men were overfed during 8 wk (+760 kcal/day). Endotoxemia, sCD14, LBP, and IL-6 were measured before and after overfeeding (OF) at fasting (n = 18) and postprandially (subcohort, n = 8). OF did not modify fasting IL-6 but increased the LBP/sCD14 ratio (P = 0.017). Subjects were categorized into tertiles for LBP/sCD14 ratio variation. Subjects in the highest tertile (+90% LBP/sCD14) increased plasma IL-6 (+26%) versus the lowest tertile due to a decrease of sCD14 associated with high LBP. The postprandial accumulation of endotoxins increased after OF (+160%). However, only four responding subjects presented increased postprandial IL-6 accumulation. CONCLUSION: OF increases postprandial endotoxemia but the inflammatory outcome may be modulated by endotoxin handling in plasma. This study supports a new concept whereby inflammation setup during the initial phase of weight gain is linked to the relative variations of LBP and sCD14.

Positive interaction between prebiotics and thiazolidinedione treatment on adiposity in diet-induced obese mice.

OBJECTIVES: To investigate whether inulin-type fructan (ITF) prebiotics could counteract the thiazolidinedione (TZD, PPARγ activator) induced-fat mass gain, without affecting its beneficial effect on glucose homeostasis, in high-fat (HF) diet fed mice. METHODS: Male C57bl6/J mice were fed a HF diet alone or supplemented with ITF prebiotics (0.2 g/day × mouse) or TZD (30 mg pioglitazone (PIO)/kg body weight × day) or both during 4 weeks. An insulin tolerance test was performed after 3 weeks of treatment. RESULTS: As expected, PIO improved glucose homeostasis and increased adiponectinaemia. Furthermore, it induced an over-expression of several PPARγ target genes in white adipose tissues. ITF prebiotics modulated the PIO-induced PPARγ activation in a tissue-dependent manner. The co-treatment with ITF prebiotics and PIO maintained the beneficial impact of TZD on glucose homeostasis and adiponectinaemia. Moreover, the combination of both treatments reduced fat mass accumulation, circulating lipids and hepatic triglyceride content, suggesting an overall improvement of metabolism. Finally, the co-treatment favored induction of white-to-brown fat conversion in subcutaneous adipose tissue, thereby leading to the development of brite adipocytes that could increase the oxidative capacity of the tissue. CONCLUSIONS: ITF prebiotics decrease adiposity and improve the metabolic response in HF fed mice treated with TZD.

Curcuma longa extract associated with white pepper lessens high fat diet-induced inflammation in subcutaneous adipose tissue.

BACKGROUND: Supra-nutritional doses of curcumin, derived from the spice Curcuma longa, have been proposed as a potential treatment of inflammation and metabolic disorders related to obesity. The aim of the present study was to test whether Curcuma longa extract rich in curcumin and associated with white pepper (Curcuma-P®), at doses compatible with human use, could modulate systemic inflammation in diet-induced obese mice. We questioned the potential relevance of changes in adiposity and gut microbiota in the effect of Curcuma-P® in obesity. METHODOLOGY/PRINCIPAL FINDINGS: Mice were fed either a control diet (CT), a high fat (HF) diet or a HF diet containing Curcuma longa extract (0.1 % of curcumin in the HF diet) associated with white pepper (0.01 %) for four weeks. Curcumin has been usually combined with white pepper, which contain piperine, in order to improve its bioavailability. This combination did not significantly modify body weight gain, glycemia, insulinemia, serum lipids and intestinal inflammatory markers. Tetrahydrocurcumin, but not curcumin accumulated in the subcutaneous adipose tissue. Importantly, the co-supplementation in curcuma extract and white pepper decreased HF-induced pro-inflammatory cytokines expression in the subcutaneous adipose tissue, an effect independent of adiposity, immune cells recruitment, angiogenesis, or modulation of gut bacteria controlling inflammation. CONCLUSIONS/SIGNIFICANCE: These findings support that nutritional doses of Curcuma longa, associated with white pepper, is able to decrease inflammatory cytokines expression in the adipose tissue and this effect could be rather linked to a direct effect of bioactive metabolites reaching the adipose tissue, than from changes in the gut microbiota composition.

Visceral fat accumulation during lipid overfeeding is related to subcutaneous adipose tissue characteristics in healthy men.

CONTEXT: The hypothesis of a limited expansion of sc adipose tissue during weight gain provides an attractive explanation for the reorientation of excess lipids toward ectopic sites, contributing to visceral adipose depots and metabolic syndrome. OBJECTIVE: Our objective was to define whether the characteristics of sc adipose tissue influence the partition of lipids toward abdominal fat depots during weight gain in healthy men. RESEARCH DESIGN AND METHODS: Forty-one healthy nonobese volunteers performed a 56-day overfeeding protocol (+760 kcal/d). Insulin sensitivity was estimated by euglycemic hyperinsulinemic clamp. Changes in abdominal visceral and sc adipose tissue depots were measured by magnetic resonance imaging. The fate of ingested lipids before and after overfeeding was investigated using a [d31]palmitate test meal, and gene expression was measured by real-time PCR in sc fat biopsies. RESULTS: Overfeeding led to a 2.5-kg body weight increase with large interindividual variations in abdominal sc and visceral adipose tissues. There was no relationship between the relative expansions of these 2 depots, but the increase in visceral depot was positively associated with the magnitude of the postprandial exogenous fatty acid release in the circulation during the test meal. The regulation of lipid storage-related genes (DGAT2, SREBP1c, and CIDEA) was defective in the sc fat of the subjects exhibiting the largest accumulation in visceral depot. CONCLUSIONS: Characteristics of sc adipose tissue appear therefore to contribute to the development of visceral fat depot, supporting the adipose tissue expandability theory and extending it to early stages of weight gain in nonobese subjects.

Comparison of high-temperature conversion and equilibration methods for the determination of d31-palmitic acid oxidation in man using continuous-flow isotope ratio mass spectrometry.

During nutritional interventions, the ingestion of d(31)-palmitic acid and H(2)(18)O allows the assessment of dietary fatty acid oxidation from cumulative (2)H recovery in urine and the estimation of the total body water pool (TBW) from (18)O dilution. Continuous-flow isotope ratio mass spectrometry (CF-IRMS) coupled to either equilibration or high-temperature conversion (HTC) techniques permits (2)H- and (18)O-enrichment measurements in biological fluids. Thus it was of great interest to compare these methods applied to the determination of dietary fatty acid oxidation. The linearity, accuracy and correlation between CF-equilibration and CF-HTC were first checked using (2)H- and (18)O-enriched water and urine samples. Urine samples from 14 subjects were then measured with both methods. The (2)H and (18)O raw data were normalised against calibration lines. The final aim was to study the impact of the normalised raw results on physiological data (i.e. TBW and d(31)-palmitate recovery). No significant difference was observed between the (18)O- and (2)H-enrichment measurements depending on the analytical method used. The TBW volumes calculated from the (18)O enrichments measured either with CF-equilibration or CF-HTC were not significantly different: respectively, 45.1 ± 1.0 L or 45.7 ± 1.0 L (mean ± sem, p = 0.09). The palmitic acid oxidation results obtained from the (2)H-enrichment measurements and the TBW from CF-equilibration vs. CF-HTC were not significantly different (p ≥ 0.26): with δ(2)H values of, respectively, 16.2 ± 1.6% vs. 16.2 ± 1.1% at 8 h, 18.7 ± 2.0% vs. 17.6 ± 1.3% at 12 h and 21.7 ± 1.9% vs. 21.5 ± 1.3% at 3 days post-dose (mean ± sem). Thus, even if CF-HTC was preferred because it was more practical to carry out, both methods allow the study of dietary lipid oxidation in man and generate similar results.

Emulsified lipids increase endotoxemia: possible role in early postprandial low-grade inflammation.

Low-grade inflammation is a risk factor for the onset of atherosclerosis. Little is known about the involvement of endotoxin absorption from the gut during the digestion of lipids. In the present study, we first investigated in humans the impact of a mixed meal containing dispersed lipids on postprandial endotoxemia and inflammation. We then investigated the effect of (i) oil emulsification in vivo in rats and (ii) fatty acid amounts in vitro using Caco-2 cells on postprandial endotoxemia. In humans, postprandial endotoxemia increased early after the meal. Moreover, we evidenced that the endotoxin receptor sCD14 increased during digestion and that chylomicrons could contribute to absorbed endotoxin transport. This could explain the significant peak of inflammatory cytokine IL-6 that we observed 2 h after the mixed meal. Interestingly, in rats, the emulsion led to both higher endotoxemia and hypertriglyceridemia than oil and compared to a control saline load. In vitro, incubation of Caco-2 cells with increasing fatty acid concentrations enhanced epithelial absorption of endotoxin. To our knowledge, this is the first study evidencing in healthy humans that, following a mixed meal containing lipids, increased endotoxemia is associated with raised sCD14 and a peak of IL-6. On a repeated basis, this may thus be a triggering cascade for the onset of atherosclerosis. In this respect, optimizing both dietary fat amount and structure could be a possible strategy to limit such low-grade endotoxemia and inflammation by the control of postprandial lipemia.