JoVE Visualize What is visualize?
Stop Reading. Start Watching.
Advanced Search
Stop Reading. Start Watching.
Regular Search
Find video protocols related to scientific articles indexed in Pubmed.
Can Genetic Variability in ?-Tocopherol Bioavailability Explain the Heterogeneous Response to ?-Tocopherol Supplements?
Antioxid. Redox Signal.
PUBLISHED: 10-08-2014
Show Abstract
Hide Abstract
Abstract Both vitamin E (VE) consumption and blood VE status have been negatively associated with the incidence of degenerative diseases and some cancers. However, the response to VE supplementation is very variable among individuals. This could be due to interindividual variability in VE bioavailability, due, at least partly, to genetic variations in genes involved in VE metabolism. Thus, the main objective was to identify single nucleotide polymorphisms (SNPs) that may be involved in the interindividual variability in ?-tocopherol (TOL) bioavailability. The postprandial chylomicron (CM) TOL response (area under the curve of the postprandial CM TOL concentration) to a TOL-rich meal was highly variable (coefficient of variation=81%; n=38). This response was positively correlated with the fasting plasma TOL concentration (r=0.5, p=0.004). A significant (p=1.8×10(-8)) partial least-squares regression model, which included 28 SNPs in 11 genes, explained 82% of this response. First evidence that the interindividual variability in TOL bioavailability is, at least partly, modulated by a combination of SNPs. TOL bioavailability is, at least partly, modulated by genetic variations that can affect long-term TOL status. This allows us to propose a new hypothesis that links the biological response to VE supplementation with one's individual genetic characteristics. Antioxid. Redox Signal. 00, 000-000.
Related JoVE Video
?-lactoglobulin as a vector for ?-carotene food fortification.
J. Agric. Food Chem.
PUBLISHED: 06-11-2014
Show Abstract
Hide Abstract
Food fortification is a strategy to overcome vitamin A deficiency in developing countries. Our aim was to investigate the involvement of the bovine milk protein ?-lactoglobulin (?-Lg), a potential retinoid carrier, in vitamin A absorption. In vivo experiments were conducted by force-feeding mice with retinol or ?-carotene associated with either ?-Lg or oil-in-water emulsion, with subsequent determination of both vitamin A intestinal mucosa and plasma contents. Caco-2 cells were then used to investigate the mechanisms of vitamin A uptake when delivered by either ?-Lg or mixed micelles. We showed that ?-Lg was as efficient as emulsion to promote ?-carotene, but not retinol, absorption in mice. Similar results were obtained in vitro. Interestingly, an inhibitor of the Scavenger Receptor Class B Type I significantly decreased the uptake of micellar ?-carotene but not that of ?-carotene bound to ?-Lg. Overall, we showed that ?-Lg would be a good vector for ?-carotene food fortification.
Related JoVE Video
Interindividual variability of lutein bioavailability in healthy men: characterization, genetic variants involved, and relation with fasting plasma lutein concentration.
Am. J. Clin. Nutr.
PUBLISHED: 05-07-2014
Show Abstract
Hide Abstract
Lutein accumulates in the macula and brain, where it is assumed to play physiologic roles. The bioavailability of lutein is assumed to display a high interindividual variability that has been hypothesized to be attributable, at least partly, to genetic polymorphisms.OBJECTIVES: We characterized the interindividual variability in lutein bioavailability in humans, assessed the relation between this variability and the fasting blood lutein concentration, and identified single nucleotide polymorphisms (SNPs) involved in this phenomenon.DESIGN: In a randomized, 2-way crossover study, 39 healthy men consumed a meal that contained a lutein supplement or the same meal for which lutein was provided through a tomato puree. The lutein concentration was measured in plasma chylomicrons isolated at regular time intervals over 8 h postprandially. Multivariate statistical analyses were used to identify a combination of SNPs associated with the postprandial chylomicron lutein response (0-8-h area under the curve). A total of 1785 SNPs in 51 candidate genes were selected.RESULTS: Postprandial chylomicron lutein responses to meals were very variable (CV of 75% and 137% for the lutein-supplement meal and the meal with tomato-sourced lutein, respectively). Postprandial chylomicron lutein responses measured after the 2 meals were positively correlated (r = 0.68, P < 0.0001) and positively correlated to the fasting plasma lutein concentration (r = 0.51, P < 0.005 for the lutein-supplement-containing meal). A significant (P = 1.9 × 10(-4)) and validated partial least-squares regression model, which included 29 SNPs in 15 genes, explained most of the variance in the postprandial chylomicron lutein response.Conclusions: The ability to respond to lutein appears to be, at least in part, genetically determined. The ability is explained, in large part, by a combination of SNPs in 15 genes related to both lutein and chylomicron metabolism. Finally, our results suggest that the ability to respond to lutein and blood lutein status are related. This trial was registered at clinicaltrials.gov as NCT02100774.
Related JoVE Video
The postprandial chylomicron triacylglycerol response to dietary fat in healthy male adults is significantly explained by a combination of single nucleotide polymorphisms in genes involved in triacylglycerol metabolism.
J. Clin. Endocrinol. Metab.
PUBLISHED: 01-13-2014
Show Abstract
Hide Abstract
The postprandial chylomicron (CM) triacylglycerol (TG) response to dietary fat, which is positively associated with atherosclerosis and cardiovascular disease risk, displays a high interindividual variability. This is assumed to be due, at least partly, to polymorphisms in genes involved in lipid metabolism. Existing studies have focused on single nucleotide polymorphisms (SNPs), resulting in only a low explained variability.
Related JoVE Video
Bioavailability of vitamin E in humans: an update.
Nutr. Rev.
PUBLISHED: 04-24-2013
Show Abstract
Hide Abstract
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, as well 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.
Related JoVE Video
Interactions of ?-Lactoglobulin Variants A and B with Vitamin A. Competitive Binding of Retinoids and Carotenoids.
J. Agric. Food Chem.
PUBLISHED: 04-19-2013
Show Abstract
Hide Abstract
?-Lactoglobulin (?-Lg) is the major whey protein of bovine milk present at a concentration of 2-3 g L(-1). Its biological role is still not well-known. However, many studies have suggested that ?-Lg may play either nutritional or specific transporter role. The high affinity of ?-Lg for retinol and other retinoids was reported. The results of interaction studies of ?-Lg with carotenoids, that is, ?-carotene, ?-cryptoxanthin, and ?-carotene, which display similar structures are reported in this study. The affinities of ?-Lg for binding of retinoids and carotenoids were compared, providing more information about the binding site(s) of these molecules by ?-Lg. Interactions were followed by the measurements of quenching of ?-Lg tryptophan fluorescence and retinol fluorescence. The obtained results indicate that carotenoids are bound by ?-Lg with high affinity of the order of 10(-8) M. Measurement of retinol competition with carotenoids for binding by ?-Lg suggests that the binding of these two ligands occurs at two different sites of ?-Lg.
Related JoVE Video
CD36 and SR-BI are involved in cellular uptake of provitamin A carotenoids by Caco-2 and HEK cells, and some of their genetic variants are associated with plasma concentrations of these micronutrients in humans.
J. Nutr.
PUBLISHED: 02-20-2013
Show Abstract
Hide Abstract
Scavenger receptor class B type I (SR-BI) and cluster determinant 36 (CD36) have been involved in cellular uptake of some provitamin A carotenoids. However, data are incomplete (e.g., there are no data on ?-carotene), and it is not known whether genetic variants in their encoding genes can affect provitamin A carotenoid status. The objectives were 1) to assess the involvement of these scavenger receptors in cellular uptake of the main provitamin A carotenoids (i.e., ?-carotene, ?-carotene, and ?-cryptoxanthin) as well as that of preformed vitamin A (i.e., retinol) and 2) to investigate the contribution of genetic variations in genes encoding these proteins to interindividual variations in plasma concentrations of provitamin A carotenoids. The involvement of SR-BI and CD36 in carotenoids and retinol cellular uptake was investigated in Caco-2 and human embryonic kidney (HEK) cell lines. The involvement of scavenger receptor class B type I (SCARB1) and CD36 genetic variants on plasma concentrations of provitamin A carotenoids was assessed by association studies in 3 independent populations. Cell experiments suggested the involvement of both proteins in cellular uptake of provitamin A carotenoids but not in that of retinol. Association studies showed that several plasma provitamin A carotenoid concentrations were significantly different (P < 0.0083) between participants who bore different genotypes at single nucleotide polymorphisms and haplotypes in CD36 and SCARB1. In conclusion, SR-BI and CD36 are involved in cellular uptake of provitamin A carotenoids, and genetic variations in their encoding genes may modulate plasma concentrations of provitamin A carotenoids at a population level.
Related JoVE Video
Iron-induced oxidation of (all-E)-?-carotene under model gastric conditions: kinetics, products, and mechanism.
Free Radic. Biol. Med.
PUBLISHED: 02-18-2013
Show Abstract
Hide Abstract
The stability of (all-E)-?-carotene toward dietary iron was studied in a mildly acidic (pH 4) micellar solution as a simple model of the postprandial gastric conditions. The oxidation was initiated by free iron (Fe(II), Fe(III)) or by heme iron (metmyoglobin, MbFe(III)). Fe(II) and metmyoglobin were much more efficient than Fe(III) at initiating ?-carotene oxidation. Whatever the initiator, hydrogen peroxide did not accumulate. Moreover, ?-carotene markedly inhibited the conversion of Fe(II) into Fe(III). ?-Carotene oxidation induced by Fe(II) or MbFe(III) was maximal with 5-10 eq Fe(II) or 0.05-0.1 eq MbFe(III) and was inhibited at higher iron concentrations, especially with Fe(II). UPLC/DAD/MS and GC/MS analyses revealed a complex distribution of ?-carotene-derived products including Z-isomers, epoxides, and cleavage products of various chain lengths. Finally, the mechanism of iron-induced ?-carotene oxidation is discussed. Altogether, our results suggest that dietary iron, especially free (loosely bound) Fe(II) and heme iron, may efficiently induce ?-carotene autoxidation within the upper digestive tract, thereby limiting its supply to tissues (bioavailability) and consequently its biological activity.
Related JoVE Video
Inhibition of iron-induced lipid peroxidation by newly identified bacterial carotenoids in model gastric conditions: comparison with common carotenoids.
Food Funct
PUBLISHED: 02-16-2013
Show Abstract
Hide Abstract
Newly identified spore-forming pigmented marine bacteria, Bacillus indicus HU36 and Bacillus firmus GB1, are sources of carotenoids (mainly 15 yellow and orange pigments and 13 pink pigments, respectively) with original structures. These bacterial carotenoids were evaluated for their ability to inhibit the iron-induced peroxidation of linoleic acid micelles, or sunflower oil-in-water emulsions, in comparison with ?-carotene, lycopene and astaxanthin. Lipid peroxidation was carried out in acidic conditions and initiated by dietary heme or non-heme iron (metmyoglobin or Fe(II), respectively) so as to simply simulate the postprandial gastric medium, a possible site for dietary oxidative stress. Lipid hydroperoxide formation and carotenoid consumption were followed by UV-vis spectroscopy and appropriate indicators of the antioxidant activity were estimated in each model. The bacterial carotenoids were found to be better inhibitors of heme-induced lipid peroxidation than the reference carotenoids as a likely consequence of their location closer to the interface in micelles and lipid droplets. However, this trend was not confirmed in lipid peroxidation induced by non-heme iron, possibly because of the redox recycling of Fe(II) by carotenoids. The quantitative kinetic analysis of the peroxidation curves suggests that the carotenoids mainly inhibit the propagation phase of lipid peroxidation by direct scavenging of the lipid peroxyl radicals, in agreement with independent experiments showing that carotenoids are unable to reduce the one-electron oxidized form of metmyoglobin (ferrylmyoglobin), a model of initiating species in heme-induced lipid peroxidation. Overall, carotenoids from Bacillus indicus HU36 and Bacillus firmus GB1 were found to be interesting antioxidants to fight postprandial oxidative stress in the stomach.
Related JoVE Video
The distribution and relative hydrolysis of tocopheryl acetate in the different matrices coexisting in the lumen of the small intestine during digestion could explain its low bioavailability.
Mol Nutr Food Res
PUBLISHED: 01-20-2013
Show Abstract
Hide Abstract
Vitamin E is present in feed and food mainly as d-?-tocopherol (d-?-TOL) but also as all-rac-?-tocopheryl acetate (rac-?-TAC) through supplementation. Its absorption efficiency is low compared to that of triacylglycerols. The aim of this work was thus to study the fate of TAC during digestion.
Related JoVE Video
Interlocking of ?-carotene in beta-lactoglobulin aggregates produced under high pressure.
Food Chem
PUBLISHED: 01-02-2013
Show Abstract
Hide Abstract
Vitamin A deficiency is one of the major causes of mortality and morbidity in the developing World. This deficiency can be prevented by alimentary or pharmaceutical supplementation. However, both vitamin A oxidation and isomerization should be prevented, as these phenomenons result in loss of nutritional efficacy. The aim of this study was to investigate the effect of a food protein matrix, ?-lactoglobulin (?-Lg) aggregates produced by high pressure (HP), on the stabilization of ?-carotene during storage and gastro-duodenal digestion and therefore on its bioavailability. In vitro gastro-duodenal digestion of ?-Lg aggregates entrapping ?-carotene showed that up to 12% and 33% of total ?-carotene was released after peptic and pancreatic digestion, respectively. Overall, our study showed that ?-Lg aggregates are efficient for caging and stabilization of ?-carotene during storage and digestion. Hence, it may be an interesting approach for the protection and the delivery of vitamin A.
Related JoVE Video
The proportion of lycopene isomers in human plasma is modulated by lycopene isomer profile in the meal but not by lycopene preparation.
Br. J. Nutr.
PUBLISHED: 09-09-2011
Show Abstract
Hide Abstract
Dietary lycopene consists mostly of the (all-E) isomer. Upon absorption, (all-E) lycopene undergoes isomerisation into various (Z)-isomers. Because these isomers offer potentially better health benefits than the (all-E) isomer, the aim of the present study was to investigate if the profile of lycopene isomers in intestinal lipoproteins is affected by the profile of lycopene isomers in the meal and by the tomato preparation. Six postprandial, crossover tests were performed in healthy men. Three meals provided about 70 % of the lycopene as (Z)-isomers, either mainly as 5-(Z) or 13-(Z), or as a mixture of 9-(Z) and 13-(Z) lycopene, while three tomato preparations provided lycopene mainly as the (all-E) isomer. Consumption of the 5-(Z) lycopene-rich meal led to a high (60 %) proportion of this isomer in TAG-rich lipoproteins (TRL), indicating a good absorption and/or a low intestinal conversion of this isomer. By contrast, consumption of meals rich in 9-(Z) and 13-(Z) lycopene isomers resulted in a low level of these isomers but high amounts of the 5-(Z) and (all-E) isomers in TRL. This indicates that the 9-(Z) and 13-(Z) isomers were less absorbed or were converted into 5-(Z) and (all-E) isomers. Dietary (Z)-lycopene isomers were, therefore, differently isomerised and released in TRL during their intestinal absorption in men. Consuming the three meals rich in (all-E) lycopene resulted in similar proportions of lycopene isomers in TRL: 60 % (all-E), 20 % 5-(Z), 9 % 13-(Z), 2 % 9-(Z) and 9 % unidentified (Z)-isomers. These results show that the tomato preparation has no impact on the lycopene isomerisation occurring during absorption in humans.
Related JoVE Video
Genetic variations involved in interindividual variability in carotenoid status.
Mol Nutr Food Res
PUBLISHED: 05-13-2011
Show Abstract
Hide Abstract
As shown in most clinical studies dedicated to carotenoids, there is a huge interindividual variability in absorption, and blood and tissue responses, of dietary carotenoids. The recent discovery that several proteins are involved in carotenoid metabolism in humans has prompted a possible explanation for this phenomenon: genetic variants in genes encoding for these proteins may affect their expression or activity, and in turn carotenoid metabolism and carotenoid status. The proteins clearly identified so far are (i) the carotene oxygenases ?,?-carotene-15,15-monooxygenase (BCMO1) and ?,?-carotene-9,10-oxygenase (BCDO2), which are involved in carotenoid cleavage, (ii) scavenger receptor class B type I (SR-BI), cluster determinant 36 (CD36), and Niemann Pick C1-like 1 (NPC1L1), which are involved in carotenoid uptake by cells, and (iii) glutathione S-transferase Pi 1 (GSTP1) and human retinal lutein-binding protein (HR-LBP), which are involved in the transport of xanthophylls in the retina. Other proteins, such as ATP-binding cassette subfamily G member 5 (ABCG5) and the fatty acid-binding proteins (FABPs) are also apparently involved although firmer evidence is still required. A genome-wide association study, as well as several candidate gene association studies, has shown that groups of subjects bearing different alleles in single nucleotide polymorphisms located in or near several of the above-mentioned genes display different blood and/or tissue concentrations of carotenoids. Further studies are needed to identify all the proteins involved in carotenoid metabolism and assess whether other types of genetic variation, e.g. copy number variants and epigenetic modifications, can modulate carotenoid status. One potential application of such research could be personalized dietary guidelines for carotenoids according to individual genetic characteristics.
Related JoVE Video
Proteins involved in uptake, intracellular transport and basolateral secretion of fat-soluble vitamins and carotenoids by mammalian enterocytes.
Prog. Lipid Res.
PUBLISHED: 04-18-2011
Show Abstract
Hide Abstract
Our understanding of the molecular mechanisms responsible for fat-soluble vitamin uptake and transport at the intestinal level has advanced considerably over the past decade. On one hand, it has long been considered that vitamin D and E as well as ?-carotene (the main provitamin A carotenoid in human diet) were absorbed by a passive diffusion process, although this could not explain the broad inter-individual variability in the absorption efficiency of these molecules. On the other hand, it was assumed that preformed vitamin A (retinol) and vitamin K1 (phylloquinone) absorption occurred via energy-dependent processes, but the transporters involved have not yet been identified. The recent discovery of intestinal proteins able to facilitate vitamin E and carotenoid uptake and secretion by the enterocyte has spurred renewed interest in studying the fundamental mechanisms involved in the absorption of these micronutrients. The proteins identified so far are cholesterol transporters such as SR-BI (scavenger receptor class B type I), CD36 (cluster determinant 36), NPC1L1 (Niemann-Pick C1-like 1) or ABCA1 (ATP-Binding Cassette A1) displaying a broad substrate specificity, but it is likely that other membrane proteins are also involved. After overviewing the metabolism of fat-soluble vitamins and carotenoids in the human upper gastrointestinal lumen, we will focus on the putative or identified proteins participating in the intestinal uptake, intracellular transport and basolateral secretion of these fat-soluble vitamins and carotenoids, and outline the uncertainties that need to be explored in the future. Identifying the proteins involved in intestinal uptake and transport of fat-soluble vitamins and carotenoids across the enterocyte is of great importance, especially as some of them are already targets for the development of drugs able to slow cholesterol absorption. Indeed, these drugs may also interfere with lipid vitamin uptake. A better understanding of the molecular mechanisms involved in fat-soluble vitamin and carotenoid absorption is a priority to better optimize their bioavailability.
Related JoVE Video
Phytosterol ester processing in the small intestine: impact on cholesterol availability for absorption and chylomicron cholesterol incorporation in healthy humans.
J. Lipid Res.
PUBLISHED: 04-11-2011
Show Abstract
Hide Abstract
Phytosterols (plant sterols and stanols) can lower intestinal cholesterol absorption, but the complex dynamics of the lipid digestion process in the presence of phytosterol esters (PEs) are not fully understood. We performed a clinical experiment in intubated healthy subjects to study the time course of changes in the distribution of all lipid moieties present in duodenal phases during 4 h of digestion of meals with 3.2 g PE (PE meal) or without (control meal) PE. In vitro experiments under simulated gastrointestinal conditions were also performed. The addition of PE did not alter triglyceride (TG) hydrolysis in the duodenum or subsequent chylomicron TG occurrence in the circulation. In contrast, cholesterol accumulation in the duodenum aqueous phase was markedly reduced in the presence of PE (-32%, P < 0.10). In vitro experiments confirmed that PE reduces cholesterol transfer into the aqueous phase. The addition of PE resulted in a markedly reduced presence of meal-derived hepta-deuterated cholesterol in the circulation, i.e., in chylomicrons (-43%, PE meal vs. control; P < 0.0001) and plasma (-54%, PE meal vs. control; P < 0.0001). The present data show that addition of PE to a meal does not alter TG hydrolysis but displaces cholesterol from the intestinal aqueous phase and lowers chylomicron cholesterol occurrence in humans.
Related JoVE Video
Vitamin D intestinal absorption is not a simple passive diffusion: evidences for involvement of cholesterol transporters.
Mol Nutr Food Res
PUBLISHED: 01-31-2011
Show Abstract
Hide Abstract
It is assumed that vitamin D is absorbed by passive diffusion. However, since cholecalciferol (vitamin D(3) ) and cholesterol display similar structures, we hypothesized that common absorption pathways may exist.
Related JoVE Video
Phytosterols can impair vitamin D intestinal absorption in vitro and in mice.
Mol Nutr Food Res
PUBLISHED: 01-25-2011
Show Abstract
Hide Abstract
Adequate vitamin D status is necessary and beneficial for health, although deficiency and insufficiency are very common. As cholecalciferol (vitamin D(3) ) structure is close to cholesterol structure, we hypothesized that phytosterols, frequently used to decrease cholesterol, intestinal absorption and consequently to reduce hypercholesterolemia, may also interact with cholecalciferol absorption.
Related JoVE Video
Polymorphisms in the CD36/FAT gene are associated with plasma vitamin E concentrations in humans.
Am. J. Clin. Nutr.
PUBLISHED: 01-12-2011
Show Abstract
Hide Abstract
Blood vitamin E concentrations are modulated by dietary, metabolic, and genetic factors. CD36 (cluster of differentiation 36), a class B scavenger receptor, might be involved in tissue vitamin E uptake and thus would influence blood vitamin E concentrations.
Related JoVE Video
Genetic variants in BCMO1 and CD36 are associated with plasma lutein concentrations and macular pigment optical density in humans.
Ann. Med.
PUBLISHED: 11-22-2010
Show Abstract
Hide Abstract
Lutein is recovered at high concentration in the human macula lutea. Recent studies suggest that this micronutrient might be implicated in prevention of age-related macular degeneration.
Related JoVE Video
CD36 is involved in lycopene and lutein uptake by adipocytes and adipose tissue cultures.
Mol Nutr Food Res
PUBLISHED: 08-24-2010
Show Abstract
Hide Abstract
Carotenoids are mainly stored in adipose tissue. However, nothing is known regarding the uptake of carotenoids by adipocytes. Thus, our study explored the mechanism by which lycopene and lutein, two major human plasma carotenoids, are transported.
Related JoVE Video
Vitamin E decreases endogenous cholesterol synthesis and apo-AI-mediated cholesterol secretion in Caco-2 cells.
J. Nutr. Biochem.
PUBLISHED: 02-09-2010
Show Abstract
Hide Abstract
Intestine is the gateway for newly absorbed tocopherols. This organ also plays a crucial role in cholesterol metabolism. Because tocopherols are known to impact cholesterol metabolism in the liver, we hypothesized that tocopherols could also modulate cholesterol metabolism in the intestine. This study aimed to verify this hypothesis and to unveil the mechanisms involved, using Caco-2 cells as a model of the human intestinal cell. Both ?- and ?-tocopherol significantly (P<.05) decreased endogenous cholesterol synthesis and apo-AI-mediated cholesterol secretion in Caco-2 cells. Tocopherols down-regulated (P<.05) up to half of the genes involved in the cholesterol synthesis pathway, together with CYP27A1, which is involved in oxysterol production. The activity of this enzyme, as well as the levels of intracellular oxysterols, was significantly diminished by tocopherols. Finally, tocopherols significantly reduced ABCA1 mRNA levels in Caco-2 cells. We conclude that tocopherols impair the endogenous synthesis and apo-AI-mediated secretion of cholesterol in Caco-2 cells. This effect involves a down-regulation of genes involved in the cholesterol synthesis pathway, resulting in down-regulation of CYP27A1 which, in turn, diminishes oxysterol concentrations. The outcome is a decrease of LXR activity, resulting in down-regulation of ABCA1. These data reinforce the effect of ?- and ?-tocopherol on cholesterol metabolism via gene expression regulation.
Related JoVE Video
Human fasting plasma concentrations of vitamin E and carotenoids, and their association with genetic variants in apo C-III, cholesteryl ester transfer protein, hepatic lipase, intestinal fatty acid binding protein and microsomal triacylglycerol transfer p
Br. J. Nutr.
PUBLISHED: 12-23-2009
Show Abstract
Hide Abstract
Plasma concentrations of vitamin E and carotenoids are governed by several factors, including genetic factors. Single nucleotide polymorphisms (SNP) in some genes involved in lipid metabolism have recently been associated with fasting plasma concentrations of these fat-soluble micronutrients. To further investigate the role of genetic factors that modulate the plasma concentrations of these micronutrients, we assessed whether SNP in five candidate genes (apo C-III, CETP, hepatic lipase, I-FABP and MTP) were associated with the plasma concentrations of these micronutrients. Fasting plasma vitamin E and carotenoid concentrations were measured in 129 French Caucasian subjects (forty-eight males and eighty-one females). Candidate SNP were genotyped by PCR amplification followed by restriction fragment length polymorphisms. Plasma gamma-tocopherol, alpha-carotene and beta-carotene concentrations were significantly different (P < 0.05) in subjects who carried different SNP variants in hepatic lipase. Plasma alpha-tocopherol concentrations were significantly different in subjects who had different SNP variants in apo C-III and cholesteryl ester transfer protein (CETP). Plasma lycopene concentrations were significantly different (P < 0.05) in women who had different SNP variants in intestinal fatty acid binding protein (I-FABP). Finally, there was no effect of SNP variants in microsomal TAG transfer protein upon the plasma concentrations of these micronutrients. Most of the observed differences remained significant after the plasma micronutrients were adjusted for plasma TAG and cholesterol. These results suggest that apo C-III, CETP and hepatic lipase play a role in determining the plasma concentrations of tocopherols while hepatic lipase and I-FABP may modulate plasma concentrations of carotenoids.
Related JoVE Video
Adiponectin expression is induced by vitamin E via a peroxisome proliferator-activated receptor gamma-dependent mechanism.
Endocrinology
PUBLISHED: 10-15-2009
Show Abstract
Hide Abstract
Adiponectin is a well-known adipokine secreted by adipocytes that presents insulin-sensitizing properties. The regulation of expression of this adipokine by micronutrients is largely unknown. We demonstrate here that adiponectin expression is induced in adipocytes after exposure to tocopherols via the peroxisome proliferator-activated receptor gamma (PPARgamma) pathway. Vitamin E force feeding resulted in an induction of adiponectin in mice at both mRNA and protein levels. Adiponectin mRNA and protein secretion were also increased by vitamin E (alpha- and gamma-tocopherol) in 3T3-L1 cells, together with PPARgamma mRNA, independent of an antioxidant effect. In transient transfections, both alpha- and gamma-vitamers induced the luciferase gene reporter under the control of a human adiponectin promoter via a PPAR-responsive element. The induction of adiponectin by tocopherols seems to be PPARgamma dependent, because it was blocked by the specific antagonist GW9662. Finally, we showed that intracellular concentrations of a PPARgamma endogenous ligand, 15-deoxy-Delta12,14-prostaglandin J2, increased after treatment with tocopherols in 3T3-L1 cells. In summary, vitamin E up-regulates adiponectin expression via a mechanism that implicates PPARgamma together with its endogenous ligand 15-deoxy-Delta12,14-prostaglandin J2. The induction of adiponectin via an original molecular mechanism could be considered as the basis for the beneficial effect of vitamin E on insulin sensitivity.
Related JoVE Video
rs5888 variant of SCARB1 gene is a possible susceptibility factor for age-related macular degeneration.
PLoS ONE
PUBLISHED: 06-03-2009
Show Abstract
Hide Abstract
Major genetic factors for age-related macular degeneration (AMD) have recently been identified as susceptibility risk factors, including variants in the CFH gene and the ARMS2 LOC387715/HTRA1locus. Our purpose was to perform a case-control study in two populations among individuals who did not carry risk variants for CFHY402H and LOC387715 A69S (ARMS2), called "study" individuals, in order to identify new genetic risk factors. Based on a candidate gene approach, we analyzed SNP rs5888 of the SCARB1 gene, coding for SRBI, which is involved in the lipid and lutein pathways. This study was conducted in a French series of 1241 AMD patients and 297 controls, and in a North American series of 1257 patients with advanced AMD and 1732 controls. Among these individuals, we identified 61 French patients, 77 French controls, 85 North American patients and 338 North American controls who did not carry the CFH nor ARMS2 polymorphisms. An association between AMD and the SCARB1 gene was seen among the study subjects. The genotypic distribution of the rs5888 polymorphism was significantly different between cases and controls in the French population (p<0.006). Heterozygosity at the rs5888 SNP increased risk of AMD compared to the CC genotypes in the French study population (odds ratio (OR) = 3.5, CI95%: 1.4-8.9, p<0.01) and after pooling the 2 populations (OR = 2.9, 95% CI: 1.6-5.3, p<0.002). Subgroup analysis in exudative forms of AMD revealed a pooled OR of 3.6 for individuals heterozygous for rs5888 (95% CI: 1.7-7.6, p<0.0015). These results suggest the possible contribution of SCARB1, a new genetic factor in AMD, and implicate a role for cholesterol and antioxidant micronutrient (lutein and vitamin E) metabolism in AMD.
Related JoVE Video
ATP-binding cassette transporter A1 is significantly involved in the intestinal absorption of alpha- and gamma-tocopherol but not in that of retinyl palmitate in mice.
Am. J. Clin. Nutr.
PUBLISHED: 02-06-2009
Show Abstract
Hide Abstract
It has long been assumed that newly absorbed vitamin A and E enter the body only via enterocyte-produced chylomicrons. However, recent results in cell cultures have shown that a fraction of alpha-tocopherol is secreted with intestinal HDL.
Related JoVE Video
Effect of type of TAG fatty acids on lutein and zeaxanthin bioavailability.
Br. J. Nutr.
Show Abstract
Hide Abstract
The xanthophylls lutein and zeaxanthin probably play a role in visual function and may participate in the prevention of age-related eye diseases. Although a minimum amount of TAG is required for an optimal bioavailability of these carotenoids, the effect of the type of TAG fatty acids (FA) is less clear. The aim was to assess the effect of the type of TAG FA on bioavailability of these xanthophylls. A total of three complementary models were used: an in vitro digestion model to study bioaccessibility, Caco-2 cells to study uptake efficiency and orally administered rats to study in vivo bioavailability. Results showed that lutein and zeaxanthin bioaccessibility was greater (about 20-30 %, P< 0·05) with butter and palm oil than with olive and fish oils. Mixed micelle size, which was significantly lower (about 8 %, P< 0·05) with SFA than with unsaturated FA, was inversely related to lutein and zeaxanthin bioaccessibility. There was no significant effect of the type of TAG FA on xanthophyll uptake by Caco-2 cells, but some compounds present in natural oils significantly affected xanthophyll uptake. Oral administration of rats with spinach and butter over 3 d led to a higher fasting plasma lutein concentration than oral administration with olive or fish oils. In conclusion, dietary fats rich in SFA lead to a higher bioavailability of lutein and zeaxanthin, as compared with fats rich in MUFA and PUFA. This is due partly to the higher bioaccessibility of these xanthophylls in the smaller mixed micelles produced when SFA are incorporated into mixed micelles.
Related JoVE Video
Comparable reduction in cholesterol absorption after two different ways of phytosterol administration in humans.
Eur J Nutr
Show Abstract
Hide Abstract
Consumption of phytosterols is a nutritional strategy to reduce cholesterol absorption, but the efficacy of various phytosterol intake modalities remains uncertain. The main objective was to investigate the effects of phytosterol esters (PE) provided either as a spread (dispersed in fat) during a mixed meal or as a minidrink (micro-dispersed in liquid form) after a meal.
Related JoVE Video
Effects of physicochemical properties of carotenoids on their bioaccessibility, intestinal cell uptake, and blood and tissue concentrations.
Mol Nutr Food Res
Show Abstract
Hide Abstract
Carotenoid bioavailability is affected by numerous factors. Our aim was to assess the involvement of known carotenoid physicochemical properties (e.g., hydrophobicity, van der Waals volume,…) on the transport of the main dietary carotenoids (?-carotene, lycopene, lutein, and astaxanthin, from their food matrix to their main storage tissues.
Related JoVE Video
Vitamin deficiencies in humans: can plant science help?
Plant Cell
Show Abstract
Hide Abstract
The term vitamin describes a small group of organic compounds that are absolutely required in the human diet. Although for the most part, dependency criteria are met in developed countries through balanced diets, this is not the case for the five billion people in developing countries who depend predominantly on a single staple crop for survival. Thus, providing a more balanced vitamin intake from high-quality food remains one of the grandest challenges for global human nutrition in the coming decade(s). Here, we describe the known importance of vitamins in human health and current knowledge on their metabolism in plants. Deficits in developing countries are a combined consequence of a paucity of specific vitamins in major food staple crops, losses during crop processing, and/or overreliance on a single species as a primary food source. We discuss the role that plant science can play in addressing this problem and review successful engineering of vitamin pathways. We conclude that while considerable advances have been made in understanding vitamin metabolic pathways in plants, more cross-disciplinary approaches must be adopted to provide adequate levels of all vitamins in the major staple crops to eradicate vitamin deficiencies from the global population.
Related JoVE Video
Grapefruit juices impair the bioaccessibility of ?-carotene from orange-fleshed sweet potato but not its intestinal uptake by Caco-2 cells.
J. Agric. Food Chem.
Show Abstract
Hide Abstract
Among various factors influencing ?-carotene (Bc) bioavailability, information on interactions between carotenoids or other micronutrients such as flavonoids during a meal that contains different plant-derived foods is quite limited. Because orange-fleshed sweet potato (OFSP) is an important Bc-rich staple food, a source of vitamin A in developing countries, this study focused on the effect of citrus fruit juice carotenoids and flavonoids on Bc bioaccessibility from OFSP. In vitro digestion coupled with the Caco-2 cell culture model was used to evaluate the bioaccessibility and cellular uptake of Bc from OFSP in the presence of pink grapefruit (pGF) or white grapefruit (wGF) juices. The addition of grapefruit juices significantly decreased the bioaccessibility, by up to 30%, but not the cellular uptake of Bc from boiled OFSP. Lycopene, but more probably naringin, present in grapefruit juices was suspected to be responsible for the inhibitory effect of the citrus juices on Bc bioaccessibility. This inhibition was apparently due in part to competition for incorporation between Bc and naringin into mixed micelles during in vitro digestion. In contrast, Bc uptake from dietary micelles was not impaired by naringin.
Related JoVE Video

What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.