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BACKGROUND: Hemolysis, Icterus, and Lipemia constituting the HIL index, are the most common causes of interference with accurate measurement in biochemistry. This study focuses on bilirubin interference, aiming to identify the analyses impacted and proposing a way to predict nominal interference‐free analyte concentrations, based on both analyte level and Icterus Index (I (ict)). METHODS: Sixteen common analytes were studied: alanine aminotransferase (ALT), albumin (ALB), alkaline phosphatase (ALP), amylase (AMY), aspartate aminotransferase (AST), total cholesterol (CHOLT), creatinine (CREA, enzymatic method), fructosamine (FRUC), gamma‐glutamyl transferase (GGT), HDL cholesterol (HDLc), total iron (Iron), lipase (LIP), inorganic phosphorus (Phos), total protein (PROT), triglycerides (TG), and uric acid (UA). Both the traditional 10% change in concentrations from baseline and the Total Change Level (TCL) were taken as acceptance limits. Nineteen pools of sera covering a wide range of values were tested on the Cobas® 6000 (Roche Diagnostics). I (ict) ranged from 0 to 60. RESULTS: Eight analytes increased (FRUC and Phos) or decreased (CHOLT, CREA, HDLc, PROT, TG, and UA) significantly when I (ict) increased. FRUC, HDLc, PROT, and UA showed a linear relationship when I (ict) increased. A non‐linear relationship was found for TG, CREA, and for CHOLT; this also depended on analyte levels. Others were not impacted, even at high I (ict). CONCLUSIONS: A method of estimating an interference‐free value for FRUC, HDLc, PROT, Phos, UA, TG, and CREA, and for CHOLT in cases of cholestasis, is proposed. I (ict) levels are identified based on analytical performance goals, and equations to recalculate interference‐free values are also proposed.

International audience; Background: Most people require dietaryvitamin D to achieve the recommended concentration of 25-hydroxyvitamin D [25(OH)D] in the blood. However, the response to vitamin D supplementation is highly variable among individuals. Objective: We assessed whether the variability in cholecalciferol bioavailability was associated with single-nucleotide polymorphisms (SNPs) in candidate genes. Methods: In a single-group design, 39 healthy adult men with a mean +/- SD age of 33 +/- 2 y and mean +/- SD body mass index lid kg/m(2)) of 22.9 +/- 0.3 were genotyped with the use of whole-genome microarrays. After an overnight fast, plasma 25(OH)D status was measured, and the subjects then consumed a meal that provided 5 mg cholecalciferol as a supplement. Plasma chylomicron cholecalciferol concentration was measured over 8 h, and cholecalciferol response was assessed by calculating the postprandial area under the curve. Partial least squares regression was used to test the association of SNPs in or near candidate genes (61 genes representing 3791 SNPs) with the postprandial cholecalciferol response. Results: The postprandial chylomicron cholecalciferol concentration peaked at 5.4 h. The cholecalciferol response was extremely variable among individuals (CV: 47%). It correlated with the chylomicron triglyceride (TG) response (r = 0.60; P < 0.001) but not with the fasting plasma 25(OH)D concentration (r = 0.04; P = 0.83). A significant (P = 1.32 x 10(-4)) partial least squares regression model that included 17 SNPs in 13 genes (including 5 that have been associated with chylomicron TG response) was associated with the variance in the cholecalciferol response. Conclusion: In healthy men, there is a high interindividual variability in cholecalciferol bioavailability that is associated with a combination of SNPs located in or near genes involved in both vitamin D and lipid metabolism. This trial was registered at clinicaltrials.gov as NCT02100774.

Introduction et but de l’etude Une part significative de la vitamine D presente dans l’organisme humain est produite au niveau de la peau par exposition a la lumiere ultraviolette. Neanmoins, pour obtenir ou maintenir un statut en vitamine D satisfaisant, une majorite d’individus doit consommer de la vitamine D, soit incluse dans l’alimentation, soit sous forme de supplements. Il a ete montre que la reponse sanguine a la supplementation en vitamine D presentait une forte variabilite interindividuelle. En outre, le transport de la vitamine D est en partie dependant de proteines. Enfin, nous avons montre que la biodisponibilite d’autres micronutriments lipidiques (tocopherol, luteine, lycopene et beta-carotene), qui possedent des mecanismes d’absorption en commun avec le cholecalciferol (D3), etait en partie modulee par des polymorphismes mononucleotidiques (SNPs) dans des genes impliques dans le transport intestinal de ces micronutriments et dans le metabolisme des chylomicrons. L’objectif principal de cette etude etait donc d’identifier des SNPs associes avec la variabilite interindividuelle de la biodisponibilite de la D3. Materiel et methodes Trente-neuf hommes adultes en bonne sante ont ete genotypes a l’aide de puces a ADN genome entier. Ils ont consomme un repas contenant 5 g de D3 sous forme de supplement. La concentration en D3 et en calcifediol (25(OH)D) dans les chylomicrons plasmatiques a ete mesuree a intervalles de temps reguliers jusqu’a 8 h apres le repas. L’association entre des SNPs dans des genes impliques dans le metabolisme de la vitamine D et des lipides (61 genes candidats representant 3791 SNPs) et la reponse postprandiale en D3 dans les chylomicrons a ete analysee par regression des moindres carres partiels (regression PLS). Resultats La concentration postprandiale en D3 des chylomicrons a atteint son maximum 5,4 h apres le repas. Nous n’avons pas observe de variation significative de la concentration postprandiale en 25(OH)D des chylomicrons. La reponse postprandiale en D3 dans les chylomicrons presentait une forte variabilite interindividuelle (CV = 47 %). Cette reponse etait positivement correlee a la reponse postprandiale en triglycerides (r = 0,60, p Conclusion Chez des hommes adultes en bonne sante, on observe une forte variabilite interindividuelle de la biodisponibilite de la D3. Cette variabilite est associee avec une combinaison de SNPs dans des genes impliques dans le metabolisme de la vitamine D et des lipides.

The growth hormone (GH)–insulin-like growth factor-1 (IGF-1) axis is dramatically altered in patients with anorexia nervosa (AN). The aim of the present study was to investigate whether GH and IGF-1 could be predictors of outcome in patients with a restrictive form of AN. Blood levels of GH, IGF-1, adipocytokines, ghrelin, insulin, glucose, and sex and thyroid hormones were measured in eleven women inpatients with AN and in ten healthy women controls. Three stages were compared during refeeding: admission (T0), when BMI reached 16 kg/m2 (T1) and at discharge when BMI reached 17·5 kg/m2 (T2). Clinical status was assessed 6 months after discharge from hospital (T3), and remission was defined by the maintenance of a BMI ≥ 17·5 kg/m2. AN patients in remission (AN-R; n 6) had significantly higher GH levels at admission than those who relapsed (AN-NR; n 5) (PPPr2 0·88, P

Background Low plasma high-density lipoprotein-cholesterol (HDL-c) level is commonly present in obesity and represents an independent cardiovascular risk factor. However, obese patients are a very heterogeneous population and the factors and mechanisms that contribute to low HDL-c remain unclear. The aim of this study was to investigate the association between plasma HDL-c levels and plasma hormonal profiles (insulin, adiponectin, resistin, leptin and ghrelin) in subsets of class II and III obese patients. Methods Fasting plasma levels of glucose, total cholesterol, LDL-c, HDL-c, triglycerides, free fatty acids, apoproteins A-I, B-100, B-48, C-II, C-III, insulin, hs-CRP, adipocytokines (adiponectin, resistin, leptin), unacylated ghrelin, body composition (DXA) and resting energy expenditure were measured in three subsets of obese patients: 17 metabolically abnormal obese (MAO) with metabolic syndrome and the typical metabolic dyslipidaemia, 21 metabolically healthy obese (MHO) without metabolic syndrome and with a normal lipid profile, and 21 isolated low HDL-c obese patients (LHO) without metabolic syndrome, compared to 21 healthy lean control subjects. Results Insulin resistance (HOMA-IR) increased gradually from MHO to LHO and from LHO to MAO patients (p < 0.05 between MHO and MAO and between LHO and MAO). In multiple regression analysis, serum unacylated ghrelin levels were only positively and independently associated with HDL-c levels in the LHO group (p = 0.032). Conclusions These results suggest that, in class II and III obese patients with an isolated low HDL-c phenotype, unacylated ghrelin is positively associated with HDL-c level independently of insulin resistance and CRP levels, and may contribute to the highly prevalent low HDL-c level seen in obesity.

Point-of-care HbA1c measurements (POC-A1Cs) have been adopted by many diabetes clinics to improve the quality of care provided to their patients (1). Herein, we show that reliability of this approach might be questioned. POC-A1Cs routinely used in the ambulatory section of our diabetes clinic was evaluated on 100 diabetic patients (type 1, n = 58; type 2, n = 42) attending the clinic from 1 October 2011 to 30 November 2011. Patients with abnormal hemoglobin traits or shortened erythrocyte life span were excluded. Blood-capillary samples were analyzed by POC-A1C (DCA Vantage; Siemens Medical Solutions Diagnostics, Cergy-Pontoise, France) and venous EDTA-anticoagulated blood specimens by the central laboratory high-performance liquid chromatography measurement (Tosoh HLC-723 GHb G8; BioSciences, Lyon, France). Both methods were certified (NGSP/Diabetes Control and Complications Trial [DCCT] and International Federation of Clinical …

International audience; Context: Cytokine polymorphisms and dietary fat composition may influence the risk of the metabolic syndrome (MetS). Objective: The objective of the study was to determine the relationship between lymphotoxin-α (LTA), TNF-α, and IL-6 gene polymorphisms with MetS risk and investigate whether plasma fatty acid composition, a biomarker of dietary fat intake, modulated these associations. Design: Polymorphisms (LTA rs915654, TNF-α rs1800629, IL-6 rs1800797), biochemical measurements, and plasma fatty acids were determined in the LIPGENE-SU.VI.MAX study of MetS cases and matched controls (n = 1754). Results: LTA rs915654 minor A allele carriers and TNF-α rs1800629 major G allele homozygotes had increased MetS risk [odds ratio (OR) 1.37 (confidence interval [CI] 1.12–1.66), P = 0.002 and OR 1.35 (CI 1.08–1.70), P = 0.009] compared with their TT homozygotes and A allele carriers. Possession of the IL-6 rs1800797 GG genotype by the LTA and TNF-α risk genotype carriers further increased risk of the MetS [OR 2.10 (CI 1.19–3.71) P = 0.009], fasting hyperglycemia [OR 2.65 (CI 1.12–6.28), P = 0.027], high systolic blood pressure [OR 1.99 (CI 1.07–3.72), P = 0.03], and abdominal obesity [OR 1.52 (CI 1.01–2.28), P = 0.04]. Plasma polyunsaturated to saturated fat ratio exacerbated these effects; subjects in the lowest 50th percentile had even greater risk of the MetS [OR 4.40 (CI 1.55–12.45), P = 0.005], fasting hyperglycemia, high systolic blood pressure, and abdominal obesity (P < 0.05). Conclusions: LTA, TNF-α, and IL-6 genotype interactions increased MetS risk, which was further exacerbated by a low plasma polyunsaturated to saturated fat exposure, indicating important modulation of genetic risk by dietary fat exposure

Dry emulsions prepared from saccharose (SAC), Labrafil M 1944 CS, sesamol (SEOH), and hydro- xypropylmethylcellulose (HPMC) or sodium caseinate (SC) by grinding or dissolution, and different desiccation tech- niques (spray (SD)- or freeze (FD)-drying, or heating at 60 C) were investigated to determine possible interactions between mixture components. The goal of this study was to determine the best formulation which will regenerate per- fectly, after water dilution of dry emulsions, the initial liquid emulsion with the same characteristics that before drying. The morphological state of SAC and dry emulsions were determined by scanning electron microscopy analysis (SEM) analysis. Glass transition temperature, and melting (endo- thermic), decomposition (endothermic), oxidation (exo- thermic) peak temperatures and enthalpies were measured by differential scanning calorimetry (DSC). The antioxidant activity of emulsions was evaluated through their ability to reduce 1,1-diphenyl-2-picrylhydrazil (DPPH) free radical. SEM analysis showed that SD-prepared, SC-containing dry emulsions formed better spherical particles with smooth surface at about 5 lm diameter as compared to emulsion containing HPMC. These former emulsions also showed more thermal stability by DSC. The combined results of the three analytical techniques emphasized the importance of the dry emulsion process regarding the efficiency and the ther- mal stability of antioxidant substances. A specific physical and/or chemical combination (such as hydrogen bond) suf- ficiently stable, at about 150 C, could be suggested when the technique used for dry emulsion preparation was SD. After water dilution, this dry emulsion obtained from quaternary mixture: SAC, Labrafil, SEOH and SC, will regenerate the initial liquid emulsion with the same characteristics that before drying.

International audience; Background: The dietary guidelines targeted at reducing cardiovascular risk lead to largely heterogeneous responses in which genetic determinants are largely involved. Objectives: We evaluated the effect of fatty acid binding protein 2 (FABP2) Ala54Thr and microsomal triacylglycerol transfer protein (MTTP) –493G/T allelic variations on plasma lipid markers, at baseline and on the response to the 3-mo Medi-RIVAGE primary prevention study. Design: Subjects with moderate cardiovascular disease risk (n = 169) were advised to reduce total and saturated dietary fats and to increase intake of monounsaturated and polyunsaturated fats. They were genotyped for FABP2 Ala54Thr and MTTP –493G/T allelic variations, and plasma was processed for cardiovascular risk marker analyses. Results: At baseline, men and women homozygous for Thr54 presented a significant opposite profile for plasma oleic acid (18:1), triacylglycerol-rich lipoprotein (TRL) cholesterol, and TRL phospholipids. In addition, all Thr/Thr men presented higher 18:1 values than did women. For the MTTP –493G/T polymorphism, although all TT subjects presented high apolipoprotein B-48, a genotype x sex interaction was present for palmitic acid, linolenic acid, eicosatrienoic acid, and insulin. The prudent diet clearly improved plasma lipid markers. FABP2 genotype did not interact much with the amplitude of the response. However, for MTTP polymorphism, men homozygous for the T allele displayed a significantly more pronounced response than did men carrying the G allele, which is particularly evident by their larger decrease in the Framingham score. Conclusions: These 2 polymorphic loci are thus differently associated with the baseline lipid markers as well as with the response to nutritional recommendations, but both presented a marked sex-specific profile, with the response to diet being particularly efficient in men homozygous for the MTTP –493T allele

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Background: Apolipoprotein C-II and apolipoprotein C-III play an important and complex role in plasma triglycerides metabolism, respectively, as inhibitor and activator of lipoprotein lipase. Thus, they appear to be suitable markers for clinical studies of triglyceride-rich lipoproteins and related cardiovascular risk. Our aim was to evaluate, for routine analysis, the accuracy to quantify these apolipoprotein in human sera. Methods: Precision (intra- and inter-run), limit of detection and quantification, linearity, common interferents (lipids, haemoglobin, bilirubin) and reference intervals were determined according to guidelines of the French Society of Clinical Biology and ISO Norm 5725 specifications. Results: Intra- and inter-run CVs were respectively less than 5.0% and 7.5%. Linearities extended from 10.8 mg/L to 112.9 mg/L for apolipoprotein C-II and from 31.8 mg/L to 375.5 mg/L for apolipoprotein C-III. Haemolysis (up to 227.6 μmol/L haemoglobin) and lipemia (up to 19.3 mmol/L triglycerides) do not interfere, contrary to bilirubin, which has a positive effect above 350 μmol/L. Comparison of methods shows good agreement between immunoturbidimetric and electro-immunodiffusion methods for measuring apolipoprotein C-III in 62 samples within a wide range ( n = 62, r = 0.954, y = 3.81 × − 14.4). Conclusion: This study shows the reliability of these kits for measuring apolipoprotein C-II and apolipoprotein C-III in human sera, and their suitability for routine analysis.

Lipid, oxidative and inflammatory parameters are frequently altered in dialysis patients and may be worsened by intravenous lipid emulsions (ILE). We assessed the efficacy and tolerance of olive as compared with standard soybean oil-based ILE during intradialytic parenteral nutrition (IDPN). IDPN mixtures containing amino acids, glucose, and either olive oil (OO group,n17) or soybean oil-based ILE (SO group,n18) were administered in a 5-week randomized, double-blind study. On days 0 and 35, patients' nutritional status was assessed by BMI, normalized protein catabolic rate, predialytic creatinine, serum albumin and transthyretin; lipid metabolism by plasma LDL- and HDL-cholesterol, triacylglycerols, phospholipids, apo A-I, A-II, B, C-II, C-III, E and lipoprotein (a); oxidative status by α-tocopherol, retinol, selenium, glutathione peroxidase, malondialdehyde and advanced oxidized protein products; inflammatory status by serum C-reactive protein, orosomucoid, IL-2 and IL-6. No serious adverse event was observed. Significant changes were observed from day 0 to day 35 (P

Phytosterols can be of value in decreasing cardiovascular risk of coronary heart disease. β-Sitosterol was the most abundant sterol in the three oils studied (sunflower, olive and ‘4 oil mixture’). The total phytosterol level was the highest in the ‘4 oil mixture’ compared with the other oils studied. Tests performed on the effect of aging (heating at 50 °C for several weeks and at 100 °C for 1 h) did not show any significant variation in the phytosterol content. In contrast, heating at 200 °C for 1 h led to a 50–60% decrease of phytosterol in the oils studied and in the standard solutions. Copyright © 2005 Society of Chemical Industry

Oils obtained from seven chemotypes (thymol, linalool, geraniol, borneol, (E)-sabinene hydrate/terpinene-4-ol, p-cymene and carvacrol) of Thymus vulgaris (thyme) that exist in the South of France were analysed by gas chromatography/mass spectrometry (GC/MS) and characterised. Wild thyme growing in three departments (Bouches du Rhone, Var and Vaucluse) of Provence and in a fourth neighbouring department (Gard) was also studied. This is often the result of a mixture of three chemotypes: thymol, carvacrol and p-cymene. Linalool and (E)-sabinene hydrate/terpinene-4-ol were observed as minor chemotypes. GC/MS was also used to monitor seasonal variations in the composition of the oil obtained from thyme harvested at the same location (Gemenos, near Marseille, Bouches du Rhone) during the plant vegetative and life cycles (19 samples). Four components were determined: the phenols thymol and carvacrol and the monoterpene hydrocarbon precursors p-cymene and γ-terpinene. Results showed maximum oil (34.1 mL kg−1 dry matter) and phenolic terpenoid (95.4 mmol kg−1 dry matter) contents occurring in May, the period of flowering and harvesting. In contrast, in December the oil displayed a higher level of phenolic precursors (p-cymene and γ-terpinene, 72.8 mmol kg−1 dry matter) than phenolic terpenoids. Depending on the harvesting date, the oils isolated from southern French thyme (T. vulgaris) could have different potential biological activities. Copyright © 2005 Society of Chemical Industry

The carotenoid lutein is thought to play a role in the human eye and to protect against age-related macular degeneration. Lutein transport in the human intestine has not been characterized. We examined lutein transport processes using Caco-2 TC-7 monolayers as a model for human intestinal epithelium. Purified lutein was mixed with phospholipids, lysophospholipids, cholesterol, mono-olein, oleic acid and taurocholate to obtain lutein-rich mixed micelles that mimicked those found under physiological conditions. The micelles were added to the apical side of Caco-2 TC-7 cell monolayers for 30 min or 3 h at 37 degrees C. Absorbed lutein, i.e. the sum of lutein recovered in the scraped cells and in the basolateral chamber, was quantified by HPLC. Transport rate was measured (i) as a function of time (from 15 to 60 min), (ii) as a function of micellar lutein concentration (from 1.5 to 15 microM), (iii) at 4 degrees C, (iv) in the basolateral to apical direction, (v) after trypsin pretreatment, (vi) in the presence of beta-carotene and/or lycopene, (vii) in the presence of increasing concentrations of antibody against SR-BI (scavenger receptor class B type 1) and (viii) in the presence of increasing concentrations of a chemical inhibitor of the selective transfer of lipids mediated by SR-BI, i.e. BLT1 (blocks lipid transport 1). The rate of transport of lutein as a function of time and as a function of concentration was saturable. It was significantly lower at 4 degrees C than at 37 degrees C (approx. 50%), in the basal to apical direction than in the opposite direction (approx. 85%), and after trypsin pretreatment (up to 45%). Co-incubation with beta-carotene, but not lycopene, decreased the lutein absorption rate (approx. 20%) significantly. Anti-SR-BI antibody and BLT1 significantly impaired the absorption rate (approx. 30% and 57% respectively). Overall, these results indicate that lutein absorption is, at least partly, protein-mediated and that some lutein is taken up through SR-BI.

The aim of this study was to test the hypothesis that fasting apoprotein B-48 level might be a surrogate marker of postprandial lipemia in evaluating the risk of coronary artery disease (CAD) in a population without frank abnormality in fasting lipid profile. One hundred twenty-three patients tested by coronary angiography were selected on the criteria of absence of treatment with hypolipidemic drugs, obvious hypertriglyceridemia (2.85 mmol/L), or other conditions that may interfere with lipoprotein metabolism except diabetes. CAD was defined by more than 50% narrowing of vessel lumen, and its severity is determined by the number of arteries involved. Fasting apoprotein B-48 was measured by a competitive enzyme-linked immunosorbent assay method. There was no difference in fasting apoprotein B-48 levels between the groups with and without CAD (0.123+/-0.096 vs 0.136+/-0.125 microg/mL, respectively), whatever the sex or whether with or without diabetes. The apoprotein B-48 level was not related to the presence or the severity of CAD. There was also no correlation between fasting apoprotein B-48 levels and age, sex, body mass index, and usual fasting lipid parameters in both patients with and without angiographically proven CAD. Finally, among the features of metabolic syndrome, apoprotein B-48 was correlated with fasting triglyceride levels (r=0.357, P.01) only. In conclusion, the present study shows that in the absence of any major fasting abnormality in plasma lipid parameters, fasting apoprotein B-48 level, which has been associated with postprandial hyperlipidemia, does not predict the risk of CAD.

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International audience; To assess the influence of age on vitamin A intestinal and liver metabolism in humans, the postprandial plasma concentrations of intestinal-originated vitamin A, i.e., retinyl esters, and liver-originated vitamin A, i.e., retinol, were compared in eight young (20–30 years old) and eight elderly (64–72 years old) healthy men. Plasma and chylomicron retinyl esters and retinol concentrations were measured for up to 24 h following the intake of a test meal that contained 23,300 RE retinyl palmitate. The chylomicron retinyl palmitate response (area under the curve) was not significantly different between the two groups, but its peak was slightly delayed (1 h) in the elderly men. The proportion of the different retinyl esters secreted in the chylomicrons was not significantly different between the two groups. The postprandial plasma retinol concentration did not change in the young participants, whereas it significantly increased in the elderly. These results suggest that vitamin A intestinal absorption and retinol intestinal esterification processes are not markedly modified in the elderly, whereas the chylomicron clearance and the regulation of postprandial plasma retinol concentrations are apparently altered in these subjects.

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Two approaches were used to better understand nutritional, physio-pathological and genetic factors intervening in the great inter-individual variability of cholesterol absorption in humans (30-80%) : - INDIRECT METHOD consisting in the determination of both absorption and synthesis plasmatic markers of cholesterol, which is used in large scale studies; - a DIRECT METHOD by measuring simultaneaously two cholesterol stable isotopes, used as tracers. It is the "gold" method to determine the absorption percentage of dietary cholesterol. By using indirect method, we have shown gene-diet interactions according to sex in a population of men and women with moderate cardiovascular risks. Changing in dietary habits didn't alter cholesterol absorption statuts after 3 months of mediterranean type diet, whatever the sex. Moreover, the lowering of plasma LDL-cholesterol induced by mediterranean type diet was more marked in low-cholesterol absorbers. Thus, the cholesterol absorption status is stable over time and under differents regimes, but it modulates responsiveness to a dietary challenge. These findings illustrate the importance of cholesterol absorption status in personalized nutrition recommendations. Another finding is a gene-diet interaction in the -493G/T gene polymorphism of the microsomal triglyceride transfer protein. This polymorphism modulates the level of cholesterol absorption in women under a western diet, an effect abolished under a prudent mediterranean type diet. As indirect method shows limits, we established an original direct method, based on relative abundance of cholesterol isotopomers. Our goal is to measure simultaneously both direct and indirect plasmatic markers. Then, we could compare the two methods with the objective of applying systematically indirect method in different studies in humans., Deux approches ont été mises au point et utilisées afin de mieux comprendre les facteurs nutritionnels, physiopathologiques et génétiques intervenant dans la grande variabilité d'absorption du cholestérol chez l'homme (30-80%) :- le dosage de marqueurs plasmatiques d'absorption et de synthèse du cholestérol (METHODE INDIRECTE), qui s'applique aux grandes cohortes.- le dosage simultané de deux isotopes stables du cholestérol utilisés comme traceurs (METHODE DIRECTE), qui est la méthode de référence pour déterminer le taux d'absorption du cholestérol alimentaire.Nous avons déterminé, par la méthode indirecte, des interactions gène-régime-sexe, dans une population mixte présentant un risque cardiovasculaire modéré.On a montré qu'en modifiant les habitudes alimentaires, le statut d'absorption du cholestérol d'un sujet n'était pas modifié après 3 mois de régime méditerranéen, quel que soit le sexe. De plus la diminution du cholestérol circulant (LDL-C) induite par le régime de type méditerranéen était plus marquées chez les faibles absorbeurs de cholestérol. Le statut d'absorbeur est donc stable dans le temps et sous différents régimes, mais il module la réponse au régime, illustrant l'importance de ce statut dans la prise en charge nutritionnelle personnalisée des sujets. Nous avons aussi établi une interaction gène-régime sur le polymorphisme génétique du gène de la microsomal triglyceride transfer protein (-493G/T). Ce polymorphisme module le niveau d'absorption du cholestérol chez les femmes sous un régime occidental et cet effet est aboli sous un régime méditerranéen.La méthode indirecte présente cependant des limites. Aussi avons-nous mis au point une méthode de dosage directe originale, basée sur l'abondance relative des isotopomères du cholestérol, le but étant de mesurer simultanément les marqueurs directs et indirects et de comparer les deux méthodes en vue de l'application systématique de la méthode indirecte dans différentes études chez l'homme.