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International audience; Functional foods containing dispersible phytosterols (DPs) are recommended to reduce cholesterol absorption in humans. However, only a few studies have been conducted on the effect of DP vehicles on carotenoid bioaccessibility and uptake by intestinal cells. On a previously developed fermented maize product containing both DPs and carotenoids, we aim to evaluate the effect of DPs encapsulated by maltodextrin on the carotenoid/phytosterol/cholesterol interactions during gastro-duodenal digestion. Thanks to maltodextrin properties, beta-carotene and lycopene bioaccessibilities were significantly improved by 40.2 +/- 1.4% while that of beta-cryptoxanthin decreased by 14 +/- 0.1%. Additionally, the presence of DPs reduced the cholesterol micellarization by 51.8 +/- 4.2%. Despite a slight decrease in carotenoid uptake caused by the DP vehicle, related to micelle size, an inhibition of cholesterol accumulation by Caco-2 cells was observed. These results highlighted the key role of maltodextrin as a vehicle of DPs on carotenoid and cholesterol absorption.

Carotenoids are C-30 or C-40 based pigments with antioxidant/anti-inflammatory properties, some possessing vitamin A activity. Their dietary intake, especially within fruits and vegetables, has been associated with a decreased risk of chronic diseases, including type-2 diabetes, cardiovascular diseases, age-related macular degeneration, and several types of cancer. However, their bioavailability is wide ranging and is affected by numerous factors. Recent findings showing that the intestinal absorption of carotenoids involves proteins have raised new relevant questions about factors that can affect their bioavailability. It is therefore opportune to present a current overview of this topic.Scope and approach: This review begins by exploring what is known, as well as what is unknown, about the metabolism of carotenoids in the human upper gastrointestinal tract and then presents a methodical evaluation of factors assumed to affect carotenoid bioavailability. Key findings and conclusions : Numerous unanswered questions remain about the metabolism of carotenoids in the intestinal lumen and about the factors affecting their absorption efficiency. These gaps need to be filled to be able to better understand individual, variable responses to these compounds so as to promote guidelines towards personalized dietary recommendation in order to increase carotenoid absorption efficiency and hence their health effects. Two main conclusions can be drawn. First, the efficiency of carotenoid absorption is affected by several dietary factors (e.g. food matrix, fat, and fat-soluble micronutrients). Second, carotenoid bioavailability also depends on host-related factors, e.g. diseases, life-style habits, gender and age, as well as genetic variations including single nucleotide polymorphisms.

International audience; Scope : It is widely advised to increase pulse consumption. However, pulses are rich in molecules displaying lipid‐lowering properties, including fibers, phytates, saponins and tannins. We thus explored the effects of pulses on fat‐soluble vitamin bioavailability. Methods : We assessed vitamin A (β‐carotene and retinyl‐palmitate), vitamin E (α‐tocopherol), vitamin D (cholecalciferol) and vitamin K (phylloquinone) bioaccessibility, i.e. micellarization after in vitro digestion of meals containing either potatoes (control), household‐cooked or canned pulses. The obtained mixed micelles were delivered to Caco‐2 cells to evaluate vitamin uptake. We then specifically assessed the impact of fibers, phytates, saponins and tannins on both phylloquinone (used as a model vitamin) bioaccessibility and uptake. Results : The presence of pulses significantly decreased both vitamin bioaccessibility (up to ‐65% for β‐carotene, ‐69% for retinyl‐palmitate, ‐45% for cholecalciferol, ‐53% for α‐tocopherol and ‐67% for phylloquinone) and uptake (‐40% for retinyl‐palmitate, ‐67% for cholecalciferol, ‐50% for α‐tocopherol and ‐57% for phylloquinone). Effects on bioaccessibility, but not on uptake, were dependent on pulse cooking method. Phylloquinone bioaccessibility was specifically impacted by saponins, tannins and fibers while its uptake was impacted by saponins, fibers and phytates. Conclusion : Pulses can alter fat‐soluble micronutrient bioavailability. Pulses should thus be cooked appropriately and consumed within micronutrient‐rich meals.

With the increase in the prevalence of food-related diseases, there is a growing interest in unraveling the effect food might have on human health. A better vision of how food is broken down in the gastrointestinal tract and further metabolized is essential to clarify this link. The recent development of the ‘omics’ technologies now allows a more comprehensive view of the food-derived compounds released in the gut during digestion and the metabolites present in body fluids after intestinal absorption. The objective of the present paper is to give an overview on the latest research describing the digestion process and its relationship with food bioactivity using different ‘omics’ technologies. It emphasizes the complementarity of the ‘omics’ disciplines, i.e. transcriptomics, proteomics, metabolomics, etc. (gathered under the more generic term of ‘foodomics’) and the added value of integrating such datasets.

Purpose of review To provide an update on the genetic factors recently associated with the interindividual variability of tomato carotenoid bioavailability. Recent findings Several clinical studies have demonstrated that the main carotenoids found in tomatoes (lycopene, phytoene, phytofluene, β-carotene, lutein) all display relatively large interindividual variabilities of their bioavailability, with coefficients of variations more than 70%. The bioavailability of the parent molecules, and the blood/tissue appearance of their metabolites, is modulated by numerous proteins, involved in intestinal absorption and metabolism, blood lipoprotein transport or tissue uptake. Several single nucleotide polymorphisms (SNPs) have been associated with the interindividual variability of lycopene, lutein and β-carotene bioavailability, with six genes consistently shared between the three carotenoids, and in particular one SNP in ELOVL fatty acid elongase 2. The effects of the genetic variants taken separately are relatively low, that is each variant is usually associated with only a few percentage of the variability but multivariate analyses suggest that the additive effect of several genetic variants can explain a significant fraction of tomato carotenoid bioavailability. Summary Additional studies are needed to improve our knowledge of the genetic determinants of tomato carotenoid bioavailability but progress in this field could one day allow nutritionists to provide more personalized dietary recommendations.

C-13 beta-Carotene stability during digestion in healthy humans. Annual Meeting of the American-Society-for-Pharmacology-and-Experimental-Therapeutics (ASPET) at Experimental Biology Meeting

Small intestinal mucus has evolved to provide a robust barrier that can trap and immobilise potentially hazardous particulates such as bacteria and yet still allow the passage of nutrients to the epithelium. However, the rules governing this selective barrier function remain largely unknown, and scientific studies rely usually on animal mucus samples to explain this part of human physiology.In our study we used quantitative confocal microscopy to look at the transport characteristics in porcine ex vivo intestinal mucus of post-digestion lipid droplets that derived from in vitro digestion of yogurt. We also used a multiple-particle tracking technique to investigate the permeability of the mucus to model, sub-micron size particles. This was done in order to compare the microrheology of the mucus between different locations in the small intestine (e.g. proximal jejunum vs. distal ileum).Most importantly, we used the above experimental approaches to investigate the permeability of human ex vivo small intestinal mucus that was obtained from a number of healthy subjects. This type of human material is not easily available for research purposes. Therefore the major aim of our study was to compare the diffusion of particulates in human mucus with diffusion in porcine mucus. Our results shed light on whether the readily available porcine mucus is a reliable substitute for studying the microstructure and permeability of the mucus layer in the human small intestine. This will potentially contribute to simulating, in a more physiologically-relevant fashion, not only the digestion processes, but also the transport and absorption mechanisms in the gut. Such insights will help support efforts to both engineer fabricated foods with enhanced nutritional quality required to fight various diet-related health problems, and to overcome the failure of many pharmaceutical and nutraceutical preparations to provide effective oral delivery of active compounds.

Digestion is a highly organized sequence of biochemical, enzymatic and mechanical processes needed to release nutrients, such as peptides or free amino acids from proteins structuring complex food matrices. During the gastric phase, they are gradually denatured through the acid released into the stomach and hydrolysed by pepsin. At the intestinal phase of digestion, proteases, such as trypsin, chymotrypsin, elastase and others, are secreted to further degrade the proteins and peptides until they are absorbed through the intestinal epithelium. Static or dynamic in vitro digestion models are widely used to study this step-by-step degradation of proteins to peptides and free amino acids, raising the question on the differences between digestion models. Generation and destruction of specific peptides during in vitro digestion of skim milk powder, following either the static international consensus COST Infogest digestion protocol or the dynamic digestion model DIDGI were compared, and verified in vivo in pigs. The hydrolysis of the five most abundant milk proteins during digestion – their peptides and free amino acids – were investigated by gel electrophoresis, mass spectrometry and HPLC after the gastric and the intestinal -phase. Moreover, time-resolved in vitro digestion experiment, generation and degradation of specific peptides and release of free amino acids were followed in the two in vitro digestion models and compared with the digestion in pigs. The protein specific hydrolysis for each digestion was visualized and compared by generation of abundance-dependent peptide patterns. Highly abundant peptides observed after complete digestion indicate digestion-resistant protein sequences and represent interesting sources of bioactive peptides or allergenic epitopes. Partial-least-square data analysis (PLS-DA) comparing static and dynamic in vitro digestion with the in vivo pig data showed a high correlation of gastric and intestinal samples at the peptide level. The same analysis at the level of free amino acids showed a good correlation at the gastric phase. However, at the intestinal level, the three models formed distinct groups which could be due to absorption mechanisms in the in vivo situation.

Lutein is a xanthophyll involved in the prevention of age-related macular degeneration. Its health effects obviously depend on its bioavailability, which can be modulated by the food matrix. Indeed, the matrix can either hold back its embedded micronutrients, or protect them from a possible degradation in the upper gastrointestinal tract. Thus, the purpose of this study was to determine the impact of the matrix of canned spinach on lutein bioavailability.In vitro digestions were first used to compare lutein bioaccessibility (percentage level of lutein released from the matrix to mixed micelles) when lutein was added to the test meal either as a pure molecule or in canned spinach. Then, mixed micelles isolated from these in vitro digestions were delivered to human intestinal Caco-2 TC7 cells to assess lutein uptake and efflux. To strengthen these results, an experiment was performed in piglets to verify in vivo the impact of the canned spinach matrix on lutein bioavailability, which was evaluated by comparison of the postprandial plasma lutein responses (0-12 h area under the curve of the plasma lutein concentrations) after test meals that contained either pure lutein or lutein in canned spinach.Our results showed that lutein bioaccessibility was significantly higher when lutein was digested in spinach as compared to in vitro digestion of the pure form (+35%, p

International audience; Carotenoids are C-30 or C-40 based pigments with antioxidant/anti-inflammatory properties, some possessing vitamin A activity. Their dietary intake, especially within fruits and vegetables, has been associated with a decreased risk of chronic diseases, including type-2 diabetes, cardiovascular diseases, age-related macular degeneration, and several types of cancer. However, their bioavailability is wide ranging and is affected by numerous factors. Recent findings showing that the intestinal absorption of carotenoids involves proteins have raised new relevant questions about factors that can affect their bioavailability. It is therefore opportune to present a current overview of this topic.Scope and approach: This review begins by exploring what is known, as well as what is unknown, about the metabolism of carotenoids in the human upper gastrointestinal tract and then presents a methodical evaluation of factors assumed to affect carotenoid bioavailability.Key findings and conclusions : Numerous unanswered questions remain about the metabolism of carotenoids in the intestinal lumen and about the factors affecting their absorption efficiency. These gaps need to be filled to be able to better understand individual, variable responses to these compounds so as to promote guidelines towards personalized dietary recommendation in order to increase carotenoid absorption efficiency and hence their health effects. Two main conclusions can be drawn. First, the efficiency of carotenoid absorption is affected by several dietary factors (e.g. food matrix, fat, and fat-soluble micronutrients). Second, carotenoid bioavailability also depends on host-related factors, e.g. diseases, life-style habits, gender and age, as well as genetic variations including single nucleotide polymorphisms.

Absorption; Biodistribution; Genetic polymorphisms; Intestine; Macula lutea; International audience; Carotenoid dietary intake and their endogenous levels have been associated with a decreased risk of several chronic diseases. There are indications that carotenoid bioavailability depends, in addition to the food matrix, on host factors. These include diseases (e.g. colitis), life-style habits (e.g. smoking), gender and age, as well as genetic variations including single nucleotide polymorphisms that govern carotenoid metabolism. These are expected to explain interindividual differences that contribute to carotenoid uptake, distribution, metabolism and excretion, and therefore possibly also their association with disease risk. For instance, digestion enzymes fostering micellization (PNLIP, CES), expression of uptake/efflux transporters (SR-BI, CD36, NPC1L1), cleavage enzymes (BCO1/2), intracellular transporters (FABP2), secretion into chylomicrons (APOB, MTTP), carotenoid metabolism in the blood and liver (LPL, APO C/E, LDLR), and distribution to target tissues such as adipose tissue or macula (GSTP1, StARD3) depend on the activity of these proteins. In addition, human microbiota, e.g. via altering bile-acid concentrations, may play a role in carotenoid bioavailability. In order to comprehend individual, variable responses to these compounds, an improved knowledge on intra-/interindividual factors determining carotenoid bioavailability, including tissue distribution, is required. Here, we highlight the current knowledge on factors that may explain such intra-/interindividual differences.

International audience; Vitamin E is essential for human health and may play a role in the prevention of some degenerative diseases. Its bioavailability, however, is wide ranging and is affected by numerous factors. Recent findings showing that the intestinal absorption of vitamin E involves proteins have raised new relevant questions about factors that can affect bioavailability. It is, therefore, opportune to present a current overview of this topic. This review begins by exploring what is known, aswell as what is unknown, about the metabolization of vitamin E in the human upper gastrointestinal tract and then presents a methodical evaluation of factors assumed to affect vitamin E bioavailability. Three main conclusions can be drawn. First, the proteins ABCA1, NPC1L1, and SR-BI are implicated in the absorption of vitamin E. Second, the efficiency of vitamin E absorption is widely variable, though not accurately known (i.e., between 10% and 79%), and is affected by several dietary factors (e.g., food matrix, fat, and fat-soluble micronutrients). Finally, numerous unanswered questions remain about the metabolization of vitamin E in the intestinal lumen and about the factors affecting the efficiency of vitamin E absorption.

Bioaccessibility and intestinal cellular uptake could partly explain relative biopotency of D3 vitamers.. 4. international vitamin conference

ISI Document Delivery No.: 004QQTimes Cited: 0Cited Reference Count: 46Cited References: Pillon Nicolas J., 2011, CHEMICAL RESEARCH IN TOXICOLOGY, V24, P752Awada, Manar Soulage, Christophe O. Meynier, Anne Debard, Cyrille Plaisancie, Pascale Benoit, Berengere Picard, Gregory Loizon, Emmanuelle Chauvin, Marie-Agnes Estienne, Monique Peretti, Noel Guichardant, Michel Lagarde, Michel Genot, Claude Michalski, Marie-CarolineFrench National Research Agency (ANR)[ANR-08-ALIA-002]; ANRThis work was supported by the French National Research Agency (ANR) Grant ANR-08-ALIA-002, AGECANINOX project.M. Awada acknowledges her PhD grant from ANR. The authors thank Lucie Ribourg and Michele Viau for their work on oil mixtures. Patricia Daira is acknowledged for her help with the 4-hydroxy-2-alkenal assay. The authors thank Jean-Michel Chardigny for useful discussions. Isabelle Jouanin (Plateforme AXIOM-MetaToul, Toulouse) is acknowledged for the synthesis of internal standards to measure 4-hydroxyl-2-alkenals in fat. Yvonne Masson is acknowledged for revising the English-language manuscript.Amer soc biochemistry molecular biology incBethesda[Awada, Manar; Plaisancie, Pascale; Estienne, Monique; Michalski, Marie-Caroline] INRA, CarMeN Lab U1235, F-69621 Villeurbanne, France. [Awada, Manar; Soulage, Christophe O.; Guichardant, Michel; Lagarde, Michel; Michalski, Marie-Caroline] Inst Natl Sci Appl, IMBL, F-69621 Villeurbanne, France. [Meynier, Anne; Genot, Claude] INRA, Biopolymeres Interact Assemblages UR1268, F-44300 Nantes, France. [Debard, Cyrille; Chauvin, Marie-Agnes] INSERM, U1060, CarMeN Lab, F-69921 Oullins, France. [Benoit, Berengere; Picard, Gregory; Loizon, Emmanuelle; Peretti, Noel; Michalski, Marie-Caroline] Univ Lyon 1, F-69622 Villeurbanne, France.marie-caroline.michalski@insa-lyon.fr; International audience; Dietary intake of long-chain n-3 PUFA is now widely advised for public health and in medical practice. However, PUFA are highly prone to oxidation, producing potentially deleterious 4-hydroxy-2-alkenals. Even so, the impact of consuming oxidized n-3 PUFA on metabolic oxidative stress and inflammation is poorly described. We therefore studied such effects and hypothesized the involvement of the intestinal absorption of 4-hydroxy-2-hexenal (4-HHE), an oxidized n-3 PUFA end-product. In vivo, four groups of mice were fed for 8 weeks high-fat diets containing moderately oxidized or unoxidized n-3 PUFA. Other mice were orally administered 4-HHE and euthanized postprandially versus baseline mice. In vitro, human intestinal Caco-2/TC7 cells were incubated with 4-hydroxy-2-alkenals. Oxidized diets increased 4-HHE plasma levels in mice (up to 5-fold, P < 0.01) compared with unoxidized diets. Oxidized diets enhanced plasma inflammatory markers and activation of nuclear factor kappaB (NF-κB) in the small intestine along with decreasing Paneth cell number (up to -19% in the duodenum). Both in vivo and in vitro, intestinal absorption of 4-HHE was associated with formation of 4-HHE-protein adducts and increased expression of glutathione peroxidase 2 (GPx2) and glucose-regulated protein 78 (GRP78). Consumption of oxidized n-3 PUFA results in 4-HHE accumulation in blood after its intestinal absorption and triggers oxidative stress and inflammation in the upper intestine.

Les fruits et légumes, tout comme leurs microconstituants (polyphénols, caroténoïdes) sont impliqués dans la protection contre le développement des maladies cardiovasculaires et de certains cancers. Néanmoins, l’influence de la matrice végétale sur les propriétés nutritionnelles des fruits et légumes est encore mal connue. Les projets conduits au sein de l’UMR SQPOV visent à élucider la bioaccessibilité des caroténoïdes et des polyphénols au cours de la digestion pour des fruits et légumes couramment consommés ainsi que leur capacité protectrice vis-à -vis des lipides polyinsaturés sensibles à l’oxydation. Une partie des travaux présentés dans ce manuscrit a été menée en collaboration avec les Unités UNH et QUAPA pour leurs expertises en expérimentation animale et digestion de la viande. Polyphénols : dans une étude d’intervention, six mini-porcs ont reçu un repas de type occidental à base de viande de bœuf et d’huile de tournesol. Il a été montré que les lipides polyinsaturés de l’alimentation s’oxydaient dans le compartiment gastrique en présence des diverses formes de fer apportées par la viande. Par ailleurs, l’ajout à ce repas de fruits et légumes détaillés en dés ou de l’extrait phénolique correspondant limitait fortement l’apparition des produits d’oxydation lipidique primaires et secondaires. D’autre part, la bioaccessibilité des composés phénoliques, définie comme la fraction solubilisés dans la phase aqueuse, était généralement supérieure lorsque les composés phénoliques étaient fournis sous forme d’extrait plutôt que de fruits et légumes, en accord avec une diffusion limitée des polyphénols depuis la matrice végétale. Caroténoïdes : les études portent sur les facteurs qui affectent le transfert des caroténoïdes depuis la matrice tomate vers la phase lipidique du bol alimentaire. Cette étape est la première limitant la bioaccessibilité de ces microconstituants lipophiles. Si nos études confirment un rôle important de leur séquestration au sein des structures natives de la matrice végétale, nous montrons également que des facteurs liés aux procédés de transformation affectent leurs propriétés de diffusion, Fruit and vegetables and their microconstituants (polyphenols, carotenoids) are inversely associated with the development of cardiovascular diseases and cancers. However, the influence of the plant matrix on the nutritional properties of fruit and vegetables remains to be elucidated. Studies led at the joint research unit SQPOV intend to give an insight into the bioaccessibility of carotenoids and polyphenols in the course of digestion as well as their protective capacity towards dietary polyunsaturated lipids which are largely oxidizable. Part of the work presented in this manuscript has been conducted in collaboration with INRA research units UNH and Quapa owing to their expertise in animal experiments and meat digestion. Polyphenols : in an intervention study, six minipigs received a standard Western diet containing primarily sunflower oil and ground beef meat. Lipid oxidation was evidenced in the gastric compartment when dietary polyunsaturated lipids were in the presence of various iron forms. Additionally, meal addition with diced fruit and vegetables or the corresponding phenolic extract markedly slowed down the accumulation of primary and secondary lipid oxidation products. On the other hand, the polyphenol bioaccessibility, which is defined as the soluble fraction in the aqueous phase, proved to be higher for polyphenols provided as the extract rather than diced F&V, in agreement with a limited diffusion from the plant matrix. Carotenoids : our studies aimed at identifying factors affecting the transfer of carotenoids from the tomato matrix to the lipid phase of the gastric bolus. This step appears to be the first one limiting the bioaccessibility of these micronutrients. If our results confirmed the dominant role of their sequestration within the native structures of the plant tissues, we also showed that processing methods strongly affect their diffusivity

We used the isolated, perfused rat duodenal loop system to assess the influence of binding iron (Fe) to soluble 1–25 caseinophosphopeptide (β-CN (1–25)), produced by the hydrolysis of β casein, against the inhibition of its absorption by Zinc (Zn). Fe (100 μM) was perfused as Fe gluconate (Fe Gluc) or bound to the β-CN (1–25) (Fe CN), alone (controls) or in presence of Zn as Zn sulfate (Zn SO4) or as (Zn CN) at Fe:Zn ratios ranging from 2:1 to 1:5. Zn SO4 reduced significantly disappearance from the lumen (Q1) and net Fe absorption (FeAbs) at Fe:Zn ratios from 1:1.5 to 1:5 (p

Background Propionibacterium freudenreichii is a food grade bacterium consumed both in cheeses and in probiotic preparations. Its promising probiotic potential, relying largely on the active release of beneficial metabolites within the gut as well as the expression of key surface proteins involved in immunomodulation, deserves to be explored more deeply. Adaptation to the colon environment is requisite for the active release of propionibacterial beneficial metabolites and constitutes a bottleneck for metabolic activity in vivo. Mechanisms allowing P. freudenreichii to adapt to digestive stresses have been only studied in vitro so far. Our aim was therefore to study P. freudenreichii metabolic adaptation to intra-colonic conditions in situ. Results We maintained a pure culture of the type strain P. freudenreichii CIRM BIA 1, contained in a dialysis bag, within the colon of vigilant piglets during 24 hours. A transcriptomic analysis compared gene expression to identify the metabolic pathways induced by this environment, versus control cultures maintained in spent culture medium. We observed drastic changes in the catabolism of sugars and amino-acids. Glycolysis, the Wood-Werkman cycle and the oxidative phosphorylation pathways were down-regulated but induction of specific carbohydrate catabolisms and alternative pathways were induced to produce NADH, NADPH, ATP and precursors (utilizing of propanediol, gluconate, lactate, purine and pyrimidine and amino-acids). Genes involved in stress response were down-regulated and genes specifically expressed during cell division were induced, suggesting that P. freudenreichii adapted its metabolism to the conditions encountered in the colon. Conclusions This study constitutes the first molecular demonstration of P. freudenreichii activity and physiological adaptation in vivo within the colon. Our data are likely specific to our pig microbiota composition but opens an avenue towards understanding probiotic action within the gut in further studies comparing bacterial adaptation to different microbiota.

Absorption intestinale des xanthophylles : de l’effet de la matrice alimentaire à celui de polymorphismes génétiques.. 8. journées internationales du groupe d'experts en micronutrition oculaire (GEMO)

International audience; The health benefit of a diet rich in fruits and vegetables could be attributed to the presence of a large diversity of phytochemicals, including carotenoids. Bioactivities of carotenoids greatly depend on their bioavailability that could be modulated by the presence of other dietary constituents. Because citrus juices contain diverse antioxidant phytochemicals, the effects of flavonoids and ascorbic acid on intestinal carotenoid uptake were investigated. Experiments were conducted by using a Caco-2 cell monolayer exposed to micelles enriched in beta-cryptoxanthin (b-CX, 5 mu M) and beta-carotene (b-C, 5 mu M) in the presence of hesperetin (HES, 250 mu M), hesperidin (HES-G, 250 mu M), naringenin (NGN, 250 mu M), acid ascorbic (AA, 50 mu M) and iron. At 5 h or 24 h incubation, HES-G and HES significantly increased b-CX and b-C uptake by 1.7- and 1.6-fold, respectively (p < 0.05). Interestingly, AA was shown to eliminate the enhancing effect of HES-G by decreasing significantly the cellular uptake of carotenoids from 48.2 to 39.8% after 5 h incubation (p < 0.05). Iron decreased the carotenoid uptake, while HES-G in the presence of iron restored it, suggesting that the enhancing effect of HES-G on carotenoid uptake could be attributed to its iron-chelating activity.

The body maintains Mg2+homeostasis by renal and intestinal (re)absorption. However, the molecular mechanisms that mediate transepithelial Mg2+transport are largely unknown. Transient receptor potential melastatin 6 (TRPM6) was recently identified and shown to function in active epithelial Mg2+transport in intestine and kidney. To define the relationship between Mg2+status and TRPM6 expression, we used two models of hypomagnesemia: 1) C57BL/6J mice fed a mildly or severely Mg2+-deficient diet, and 2) mice selected for either low (MgL) or high (MgH) erythrocyte and plasma Mg2+status. In addition, the mice were subjected to a severely Mg2+-deficient diet. Our results show that C57BL/6J mice fed a severely Mg2+-deficient diet developed hypomagnesemia and hypomagnesuria and showed increased TRPM6 expression in kidney and intestine. When fed a Mg2+-adequate diet, MgL mice presented hypomagnesemia and hypermagnesuria, and lower kidney and intestinal TRPM6 expression, compared with MgH mice. A severely Mg2+-deficient diet led to hypomagnesemia and hypomagnesuria in both strains. Furthermore, this diet induced kidney TRPM6 expression in MgL mice, but not in MgH mice. In conclusion, as shown in C57BL/6J mice, dietary Mg2+-restriction results in increased Mg2+(re)absorption, which is correlated with increased TRPM6 expression. In MgL and MgH mice, the inherited Mg2+status is linked to different TRPM6 expression. The MgL and MgH mice respond differently to a low-Mg2+diet with regard to TRPM6 expression in the kidney, consistent with genetic factors contributing to the regulation of cellular Mg2+levels. Further studies of these mice strains could improve our understanding of the genetics of Mg2+homeostasis.

The present work was undertaken to evaluate the stimulatory effect of Parathyroid hormone-related peptide (PTHrP) on the intestinal calcium (Ca) absorption using stable strontium (Sr) as a surgoate marker in 10 Camels. The animals were randomly divided into two groups of five animals. Just after an oral Sr load (4.1 mmol of SrCl2), the first and the second (control) groups received either an i.v infusion of synthetic human PTHrP or solvent alone respectively. PTHrP induced a significant rise in levels of plasma Sr (52.8 ± 4.6 [mu]mol/L VS 41.7 ± 4.5 [mu]mol/L, P < 0.05, at the second hour after oral Sr load) and urinay Pi excretion comparatively with animal controls. Plasma Sr levels remained very higher in treated animals than those measured in controls until the fifth hour of experimentation (52 ± 4.7 [mu]mol/L VS 42.1 ± 4.5 [mu]mol/L, P < 0.05). PTHrP did not induce significant variation on Ca or Sr renal excretion. Our results seem to show that PTHrP may play an important role on modulation of intestinal Ca absorption in camels.

β-Cryptoxanthin (β-CX), a provitaminic carotenoid of potential interest for health, is found principally inCitrusfruit in both free and esterified forms. Little is known about the intestinal absorption of β-CX especially with regard to the esterified forms. The aim of this study was to evaluate the absorption of free and esterified β-CX using simulated digestion coupled with the Caco-2 model. Bioaccessibility was investigated by measuring the transfer of carotenoids from different citrus juices into micelles using anin vitrodigestion system. Then, carotenoid uptake was evaluated by adding carotenoid-rich micelles (from thein vitrodigestion) or synthetic micelles (made from synthetic lipids and carotenoids purified from citrus juice) to human intestinal cells (Caco-2 TC7 clone). Our results showed that β-cryptoxanthin esters (β-CXE) were partially hydrolysed during thein vitrodigestion. The bioaccessibility of free β-CX measured was significantly higher (40 (sd1·05) %) than that of β-carotene (30 (sd1·9) %) and β-CXE (16 (sd1·5) %). In the same way, the incorporation of free β-CX (27 (sd1·01) %) into synthetic micelles exceeded (P sd0·7) %) and β-CXE (8·8 (sd0·4) %). In the case of micelles fromin vitrodigestion, the uptake of β-carotene, free β-CX and β-CXE forms by Caco-2 cells was 14·3 (sd1·8), 3·9 (sd1·3), and 0·7 (sd0·08) % respectively. These results showed a preferential uptake by Caco-2 cells of β-carotene and free β-CX compared with the two esters of β-CX.

Diplôme : Dr. d'Universite

Binding iron (Fe) to the 1-25 caseinophosphopeptide obtained from enzyme hydrolysis of beta casein (beta CPP) improves Fe bioavailability in the rat. To assess the mechanisms involved in its absorption, a perfused, vascularized duodenal rat loop model was used in controls and in Fe-deficient (bleeding of 25% blood volume) rats. Inhibitors of oxidative phosphorylation [2-4 dinitrophenol (DNP)] and/or of endocytosis [phenylarsine oxide (PAO)] were added to the perfusion solution containing 50 microM Fe as beta CPP bound Fe (Fe-beta CPP) or gluconate (Fe Gluc). Fe-beta CPP enhanced Fe uptake, reduced mucosal storage, and improved net absorption both in controls and in deficient animals. DNP reduced uptake, mucosal storage, and net absorption by the same percentage in Fe-beta CPP and Fe Gluc perfused rats in both control and Fe-deficient animals. PAO decreased uptake, mucosal storage, and net absorption of Fe-beta CPP but not of Fe Gluc. At the end of the experiment Fe serum levels were increased only in Fe Gluc animals. These results confirm the improved bioavailability of beta CPP bound Fe. They suggest that at least part of its absorption can occur by a different pathway than usual Fe salts. Fe-beta CPP can be taken up by endocytosis and absorbed bound to amino acids or peptides.

International audience; Rutin and quercetin absorption and metabolism were investigated in rats after in situ perfusion of jejunum plus ileum (15 nmol/min). In contrast to rutin, a high proportion of quercetin (two-thirds) disappeared during perfusion, reflecting extensive transfer into the intestinal wall. Net quercetin absorption was not complete (2.1 nmol/min), inasmuch as 52% were reexcreted in the lumen as conjugated derivatives (7.7 nmol/min). Enterohepatic recycling contribution of flavonoids was excluded by catheterization of the biliary duct before perfusion. After a 30-min perfusion period, 0.71 µM of quercetin equivalents were detected in plasma, reflecting a significant absorption from the small intestine. The differential hydrolysis of effluent samples by glucuronidase and/or sulfatase indicates that the conjugated forms released in the lumen were 1) glucuronidated derivatives of quercetin and of its methoxylated forms (64%) and 2) sulfated form of quercetin (36%). In vitro quercetin glucuronides synthetized using jejunal and ileal microsomal fractions were similar to those recovered in the effluent of perfusion. These data suggest that glucuronidation and sulfatation take place in intestinal cells, whereas no glucurono-sulfoconjugates could be detected in the effluent. The present work shows that a rapid quercetin absorption in the small intestine is very effective together with its active conjugation in intestinal cells.

Les tanins sont des métabolites secondaires importants dans le règne végétal. Ils s’intègrent dans la défense des végétaux contre les herbivores, en particulier pour les plantes se développant dans les zones difficiles. La structure chimique de ces polyphénols leur confère une capacité très développée à se fixer sur toutes sortes de molécules, essentiellement les protéines. Ces interactions faisant intervenir les différents types de liaison possibles sont dépendantes de nombreux facteurs liés au milieu et à la structure des molécules réactantes (importance de la présence de proline chez les protéines). Ces aspects biochimiques permettent de se rendre compte de l’incidence et de la complexité des actions des tanins dans l’alimentation. La principale conséquence chez les ruminants est une diminution de la dégradation des protéines alimentaires dans le rumen, mais aussi une perturbation des activités microbiennes (rumen, caecum), une diminution de l’ingestion et même une toxicité. Les herbivores adaptés à une alimentation riche en tanins ont su développer des mécanismes de protection, en particulier la synthèse de protéines salivaires riches en proline “neutralisant” les tanins ingérés. Le tannage des protéines alimentaires par les tanins naturels est un débouché potentiel en alimentation des ruminants.

A problem encountering in the intensive culture of some teleosts is the lack of final maturation and ovulation in captivity. On the other hand, in natural conditions the reproductive cycle is season depending. In the catfish culture, for instance, manipulation of environmental parameters have not been very successful in the control of the reproductive features.

International audience

International audience

Apo-lycopenal formation and absorption in the digestive tract of healthy men.. 9. Gordon Research Conference on Carotenoids, 22-27 mai 2016, Lucca, Italie.