Validation of Knock-Out Caco-2 TC7 Cells as Models of Enterocytes of Patients with Familial Genetic Hypobetalipoproteinemias.

Abetalipoproteinemia (FHBL-SD1) and chylomicron retention disease (FHBL-SD3) are rare recessive disorders of lipoprotein metabolism due to mutations in MTTP and SAR1B genes, respectively, which lead to defective chylomicron formation and secretion. This results in lipid and fat-soluble vitamin malabsorption, which induces severe neuro-ophthalmic complications. Currently, treatment combines a low-fat diet with high-dose vitamin A and E supplementation but still fails in normalizing serum vitamin E levels and providing complete ophthalmic protection. To explore these persistent complications, we developed two knock-out cell models of FHBL-SD1 and FHBL-SD3 using the CRISPR/Cas9 technique in Caco-2/TC7 cells. DNA sequencing, RNA quantification and Western blotting confirmed the introduction of mutations with protein knock-out in four clones associated with i) impaired lipid droplet formation and ii) defective triglyceride (-57.0 ± 2.6% to -83.9 ± 1.6%) and cholesterol (-35.3 ± 4.4% to -60.6 ± 3.5%) secretion. A significant decrease in α-tocopherol secretion was also observed in these clones (-41.5 ± 3.7% to -97.2 ± 2.8%), even with the pharmaceutical forms of vitamin E: tocopherol-acetate and tocofersolan (α-tocopheryl polyethylene glycol succinate 1000). MTTP silencing led to a more severe phenotype than SAR1B silencing, which is consistent with clinical observations. Our cellular models thus provide an efficient tool to experiment with therapeutic strategies and will allow progress in understanding the mechanisms involved in lipid metabolism.

The Interindividual Variability of Phytofluene Bioavailability is Associated with a Combination of Single Nucleotide Polymorphisms.

SCOPE: Phytofluene is a colorless carotenoid with potential health benefits that displays a higher bioavailability compared to carotenoids such as lutein, ß-carotene or lycopene. Several studies suggest its bioavailability displays an elevated interindividual variability. The aim of this work is to investigate whether a combination of SNPs is associated with this variability. METHODS AND RESULTS: Thirty-seven healthy adult males consume a test meal that provides phytofluene from a tomato puree. Phytofluene concentrations are measured at fast and in chylomicrons at regular time intervals after meal intake. Identification of the combination of SNPs that best explained the interindividual variability of the phytofluene response is assessed by partial least squares regression. There is a large interindividual variability in the phytofluene response, with CV = 88%. Phytofluene bioavailability is positively correlated with fasting plasma phytofluene concentration (r = 0.57; p = 2 × 10-4 ). A robust partial least squares regression model comprising 14 SNPs near or within 11 genes (ABCA1-rs2487059, rs2515629, and rs4149316, APOC1-rs445925, CD36-rs3211881, ELOVL5-rs6941533, FABP1-rs10185660, FADS3-rs1000778, ISX-rs130461, and rs17748559, LIPC-rs17240713, LPL-rs7005359, LYPLAL1-rs1351472, SETD7-rs11936429) explains 51% (adjusted R2 ) of the interindividual variability in phytofluene bioavailability. CONCLUSIONS: This study reports a combination of SNPs that is associated with a significant part of the interindividual variability of phytofluene bioavailability in a healthy male adult population.

Vitamin A deficiency during the perinatal period induces changes in vitamin A metabolism in the offspring. The regulation of intestinal vitamin A metabolism via ISX occurs only in male rats severely vitamin A-deficient.

PURPOSE: 1) To test the hypothesis of the existence of a perinatal vitamin A (VA) programming of VA metabolism and to better understand the intestinal regulation of VA metabolism. METHODS: Offspring from rats reared on a control (C) or a VA-deficient (D) diet from 6 weeks before mating until offspring weaning, i.e., 7 weeks after mating, were themselves reared on a C or D diet for 19 weeks, resulting in the following groups: C-C (parents fed C-offspring fed C), D-C, C-D and D-D. VA concentrations were measured in plasma and liver. ß-Carotene bioavailability and its intestinal conversion rate to VA, as well as vitamin D and E bioavailability, were assessed after gavages with these vitamins. Expression of genes involved in VA metabolism and transport was measured in intestine and liver. RESULTS: C-D and D-D had no detectable retinyl esters in their liver. Retinolemia, hepatic retinol concentrations and postprandial plasma retinol response to ß-carotene gavage were higher in D-C than in C-C. Intestinal expression of Isx was abolished in C-D and D-D and this was concomitant with a higher expression of Bco1, Scarb1, Cd36 and Lrat in males receiving a D diet as compared to those receiving a C diet. ß-Carotene, vitamin D and E bio-availabilities were lower in offspring receiving a D diet as compared to those receiving a C diet. CONCLUSION: A VA-deficient diet during the perinatal period modifies the metabolism of this vitamin in the offspring. Isx-mediated regulation of Bco1 and Scarb1 expression exists only in males severely deficient in this vitamin. Severe VA deficiency impairs ß-carotene and vitamin D and E bioavailability.

Bioaccessibility and uptake by Caco-2 cells of carotenoids from cereal-based products enriched with butternut squash (Cucurbita moschata L.).

Enriching cereals-based products with bioactive compounds is a valuable strategy to improve product quality. We studied carotenoid bioaccessibility and intestinal uptake from a pumpkin-enriched porridge, cookies and sponge cakes by using in vitro digestion coupled with Caco-2 cell uptake. Among the carotenoids recovered in different products, α-carotene was the most important abundant one. However, lutein displayed a significantly higher bioaccessibility compared to α-carotene and ß-carotene in baked products (up to 10.28% compared to 1.22% and 0.88%, respectively). α-Carotene was the only carotenoid recovered in Caco-2 cells after micelle incubation. Cookie micelles led to the highest percentage of α-carotene cell uptake (2.33% and 1.38% for cookies with butter and cookies with vegetable oil, respectively) compared to the other baked products, followed by dry pumpkin puree micelles (1.31%). Overall, our data show that both bioaccessiblity and cell uptake of carotenoids from cereal-based products are variable and highly depend on food formulation and structure.

ß-Carotene Bioavailability and Conversion Efficiency Are Significantly Affected by Sex in Rats: First Observation Suggesting a Possible Hormetic Regulation of Vitamin A Metabolism in Female Rats.

SCOPE: To study the effect of variation in dietary vitamin A (VA) content on its hepatic and intestinal metabolism. METHODS AND RESULTS: Adult female and male rats are fed with diets containing 400, 2300, or 9858 IU kg-1 VA for 31-33 weeks. VA concentrations are measured in plasma and liver. Bioavailability and intestinal conversion efficiency of ß-carotene to VA are assessed by measuring postprandial plasma ß-carotene and retinyl palmitate concentrations after force-feeding rats with ß-carotene. Expression of genes involved in VA metabolism, together with concentrations of RBP4, BCO1, and SR-BI proteins, are measured in the intestine and liver of female rats. Plasma retinol concentrations are lower and hepatic free retinol concentrations are higher in females than in males. There is no effect of dietary VA content on ß-carotene bioavailability and its conversion efficiency, but bioavailability is higher and conversion efficiency is lower in females than in males. The expression of most genes exhibited a U-shaped dose response curve depending on VA intake. CONCLUSIONS: ß-Carotene bioavailability and conversion efficiency to VA are affected by the sex of rats. Results of gene expression suggest a hormetic regulation of VA metabolism in female rats.

The Complex ABCG5/ABCG8 Regulates Vitamin D Absorption Rate and Contributes to its Efflux from the Intestine.

SCOPE: Most people are vitamin D insufficient around the world. Vitamin D intestinal absorption should thus be optimized. The role of the ATP-binging cassette G5/G8 (ABCG5/G8) heterodimer in vitamin D intestinal efflux is investigated. METHODS AND RESULTS: Both cholecalciferol and 25-hydroxycholecalciferol apical effluxes are increased by ABCG5/G8 overexpression in human Griptite cells. Mice deficient in ABCG5/G8 at the intestinal level (I-Abcg5/g8-/- mice) display an accumulation of cholecalciferol in plasma in females and in liver in males compared to control animals. I-Abcg5/g8-/- mice display a delay in cholecalciferol postprandial response after gavage compared with controls. 25-Hydroxycholecalciferol transfer from plasma to lumen is observed in vivo in intestine-perfused mice, and the lack of intestinal ABCG5/G8 complex induces a decrease in this efflux, while vitamin D bile excretion remains unchanged. CONCLUSION: Overall, it is showed for the first time that the ABCG5/G8 heterodimer regulates the kinetics of absorption of dietary vitamin D by contributing to its efflux back to the lumen, and that it also participates in vitamin D transintestinal efflux.

Vitamin A Deficiency during the Perinatal Period and First Weeks of Life Modifies Vitamin A and Lipid Postprandial Metabolism in Both Female and Male Young Rats.

SCOPE: The effect of vitamin A deficiency on vitamin A and lipid postprandial metabolism in young rats is addressed, considering the effect of sex. METHODS AND RESULTS: Sprague-Dawley rats are fed either 400 UI.kg-1 vitamin A diet (vitamin A-deficient (VAD) diet) or 2300 UI.kg-1 vitamin A (control diet), before being mated. Mothers receive the same VAD or control diet during gestation and lactation. Offspring receive the same diet than mothers until 8 weeks of age. VAD diet-fed female and male offspring display a severe vitamin A deficiency with no body weight or glucose tolerance defects. Fasting plasma triglyceride concentrations are decreased in VAD diet-fed animals compared to controls (p < 0.05). Retinyl ester postprandial responses after vitamin A gavage, expressed as area under the curves, are not different in VAD diet-fed and control animals, although retinyl ester postprandial peak is significantly delayed (p < 0.05) in VAD diet-fed rats. Lipids also accumulate in the distal part of the intestine after gavage and [1-13 C]-oleate postprandial response is decreased in VAD diet-fed males. CONCLUSION: Vitamin A deficiency modulates both vitamin A absorption rate and lipid postprandial metabolism, which can partly explain the altered fasting lipid status observed in VAD diet-fed offspring.

P-glycoprotein (ABCB1) is involved in vitamin K efflux.

ABCB1 (P-glycoprotein/MDR1) is a multidrug efflux transporter that has previously been involved in cholesterol and vitamin D metabolism. Our aim was to explore whether ABCB1 is also involved in vitamin K efflux. Vitamin K apical efflux was significantly decreased in presence of ABCB1 inhibitor in Caco-2 cells (-20.4%; p < 0.05) and increased in Griptite cells overexpressing ABCB1 (+40.7%; p < 0.05). In vivo, the vitamin K postprandial response was higher in male Abcb1-/- mice after gavage compared to control animals (+115%; p < 0.05), but was unchanged in female mice. Finally, a vitamin K transintestinal efflux and a biliary vitamin K efflux were observed, but the specific involvement of ABCB1 could not be confirmed in these pathways. Overall, we showed for the first time that ABCB1 is involved in enterocyte vitamin K efflux in both cell and mouse models and regulates vitamin K absorption in mice.

A Combination of Single Nucleotide Polymorphisms is Associated with the Interindividual Variability of Cholesterol Bioavailability in Healthy Adult Males.

SCOPE: Cholesterol bioavailability displays a high interindividual variability, partly due to genetic factors. Existing studies have focused on single nucleotide polymorphisms (SNPs) analyzed individually, which only explained a minor fraction of the variability of this complex phenotype. The aim is to identify a combination of SNPs associated with a significant part of the variability in cholesterol bioavailability. METHODS AND RESULTS: Thirty-nine healthy adult males are given a standard test snack containing 80 mg heptadeuterated (D7) cholesterol. The plasma D7-cholesterol concentration is measured at equilibrium 40 h after test snack intake. The D7-cholesterol response (D7-cholesterol/total cholesterol concentration) exhibits a relatively high interindividual variability (CV = 32%). The association of exonic SNPs in candidate genes (188 genes involved in or related to cholesterol metabolism) with the plasma D7-cholesterol response is assessed by univariate statistics followed by partial least squares regression. A significant model (p-value after cross-validation ANOVA = 1.64 × 10-7 ) that includes 8 SNPs (SOAT2-rs9658625, DNAH11-rs11768670, LIPC-rs690, MVK-rs2287218, GPAM-rs10787428, APOE-rs7412, CBS-rs234706, and WRN-rs1801196) explains 59.7% of the variance in cholesterol bioavailability (adjusted R²). CONCLUSION: Here a combination of SNPs is significantly associated with the variability in dietary cholesterol bioavailability in healthy adult males.

Comparison of α-Tocopherol, α-Tocopherol Acetate, and α-Tocopheryl Polyethylene Glycol Succinate 1000 Absorption by Caco-2 TC7 Intestinal Cells.

(1) Background: vitamin E is often supplemented in the form of tocopherol acetate, but it has poor bioavailability and can fail to correct blood tocopherol concentrations in some patients with severe cholestasis. In this context, α-tocopheryl polyethylene glycol succinate 1000 (TPGS) has been of value, but very little is known about the mechanisms of its absorption. The aim of our work was to evaluate the mechanisms of absorption/secretion of TPGS compared to tocopherol acetate (TAC) and α-tocopherol by human enterocyte-like Caco-2 TC7 cells. (2) Methods: two weeks post-confluence Caco-2 cells were incubated with tocopherol- or TAC- or TPGS-rich mixed micelles up to 24 h and, following lipid extraction, TAC and tocopherol amounts were measured by high performance liquid chromatography (HPLC) in apical, cellular, and basolateral compartments. (3) Results: at equivalent concentrations of tocopherol in the apical side, the amounts of tocopherol secreted at the basolateral pole of Caco-2 cells are (i) significantly greater when the tocopherol is in the free form in the micelles; (ii) intermediate when it is in the TAC form in the micelles (p < 0.001); and (iii) significantly lower with the TPGS form (p < 0.0001). Interestingly, our results show, for the first time, that Caco-2 cells secrete one or more esterified forms of the vitamin contained in TPGS at the basolateral side.

The Effect of an Iron Supplement on Lycopene Metabolism and Absorption During Digestion in Healthy Humans.

SCOPE: To investigate the formation and absorption of lycopene (LYC) metabolites in the human upper gastrointestinal lumen, in the absence and presence of iron. METHODS: Healthy males (n = 7) consumed test meals that deliver ≈22 mg LYC + ≈0.3 mg apo-lycopenals from oleoresin without (-FeSO4 ) and with ferrous sulfate (160 mg, +FeSO4 ). Subjects were intubated with a naso-gastric/naso-duodenal tube. Digesta, blood plasma, and the triglyceride-rich lipoprotein (TRL) fractions of plasma were analyzed using LC-MS/MS, to measure LYC and apo-lycopenoids. RESULTS: Digesta LYC concentrations increased with time (p = 1.2 × 10-7 ), decrease with time × iron (p = 1.1 × 10-5 ), and remain ≈200× higher than apo-lycopenals/lycopenone. Digesta apo-8'-, -10'-, -12'-, -14'-, -15-lycopenal, and apo-13-lycopenone concentrations increased with time (p < 0.01), apo-12'-, -14'-, -15-lycopenal, apo-13-lycopenone increase with iron (p < 0.05), and time × iron decrease apo-8'-, -10'-, -12'-, -14'-, -15-lycopenal, apo-13-lycopenone concentrations (p < 0.01). A 1.9-fold decrease in LYC TRL area-under-the-time-concentration-curve is observed after the test meal +FeSO4 versus the test meal -FeSO4 (p = 0.02). Apo-lycopenals were detected in later TRL fractions, and no apo-lycopenols or apo-lycopenoic acids were observed in any samples. CONCLUSIONS: FeSO4 reduces LYC absorption. Apo-lycopenals appear to be absorbed from foods, and not made in significant quantities during digestion.

Comparison of the bioavailability and intestinal absorption sites of phytoene, phytofluene, lycopene and ß-carotene.

The mechanisms of main tomato carotenes (phytoene, phytofluene, lycopene and ß-carotene) intestinal absorption are still only partly understood. We thus compared carotene bioavailability in mice after gavage with carotene-rich oil-in-water emulsions. We also determined each carotene absorption profile along the duodenal-ileal axis of the intestine to identify their respective absorption sites and compared these profiles with the gene expression sites of their identified transporters, i.e. SR-BI and CD36. Our data show that phytofluene presented a significantly higher bioavailability compared to lycopene and ß-carotene (areas under the curve of 0.76 ±â€¯0.09 vs. 0.30 ±â€¯0.05, 0.09 ±â€¯0.05 and 0.08 ±â€¯0.01 µmol/L·h for phytofluene, phytoene, lycopene and ß-carotene, respectively). ß-Carotene was mostly converted in the proximal and median intestine. Phytoene and phytofluene accumulation tended to be more important in the distal intestine, which did not correlate with the proximal expression of both Scarb1 and CD36. Overall, these results highlight the high bioavailability of phytofluene.

Lipodystrophy-like features after total body irradiation among survivors of childhood acute leukemia.

BACKGROUND/OBJECTIVE: The number of long-term survivors of childhood acute leukemia (AL) is substantially growing. These patients are at high risk for metabolic syndrome (MS), especially those who received total body irradiation (TBI). The consequences of children's irradiation on adipose tissue (AT) development in adulthood are currently unknown. The objective of this study is to assess the impact of TBI on AT of childhood AL survivors. DESIGN: We compared the morphological and functional characteristics of AT among survivors of childhood AL who developed MS and received (n = 12) or not received (n = 12) TBI. SUBJECTS/METHODS: Body fat distribution and ectopic fat stores (abdominal visceral and liver fat) were evaluated by DEXA, MRI and 1H-spectroscopy. Functional characteristics of subcutaneous AT were investigated by studying gene expression and pre-adipocyte differentiation in culture. RESULTS: Patients who have received TBI exhibited a lower BMI (minus 5 kg/m2) and a lower waist circumference (minus 14 cm), especially irradiated women. Despite the lower quantity of intra-abdominal AT, irradiated patient displayed a nearly two-fold greater content of liver fat when compared to non-irradiated patient (17 vs 9%, P = 0.008). These lipodystrophic-like features are supplemented by molecular abnormalities in subcutaneous AT of irradiated patients: decrease of gene expression of SREBP1 (minus 39%, P = 0.01) and CIDEA (minus 36%, P = 0.004) and a clear alteration of pre-adipocyte differentiation. CONCLUSIONS: These results strongly support the direct effect of irradiation on AT, especially in women, leading to specific nonalcoholic fatty liver disease, despite lower BMI. A long-term appropriate follow-up is necessary for these patients.

The Presence of Pulses within a Meal can Alter Fat-Soluble Vitamin Bioavailability.

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. The effects of pulses on fat-soluble vitamin bioavailability were thus explored. METHODS: Vitamin A (ß-carotene and retinyl palmitate), vitamin E (α-tocopherol), vitamin D (cholecalciferol), and vitamin K (phylloquinone) bioaccessibility was evaluated by assessing 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. The impact of fibers, phytates, saponins, and tannins on both phylloquinone (used as a model vitamin) bioaccessibility and uptake were then specifically assessed. RESULTS: The presence of pulses significantly decreased both vitamin bioaccessibility (up to -65% for ß-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, are dependent on pulse cooking method. Phylloquinone bioaccessibility is specifically impacted by saponins, tannins, and fibers while its uptake is 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.

ß-Cyclodextrin Does not Alter the Bioaccessibility and the Uptake by Caco-2 Cells of Olive By-Product Phenolic Compounds.

Alperujo-a two-phase olive mill waste that is composed of olive vegetation water and solid skin, pulp, and seed fragments - is a highly valuable olive by-product due to its high content in phenolic compounds. In this study, we assessed whether ß-cyclodextrin (ß-CD), which is used to extract and protect alpejuro phenolic compounds (hydroxytyrosol-O-glucoside, tyrosol, caffeic, and p-coumaric acids) could impact on their bioaccessibility (i.e., the percentage of molecule found in the aqueous phase of the digesta) and uptake by intestinal cells, by using an in vitro digestion model and Caco-2 TC7 cells in culture, respectively. Our results showed that ß-CD did not change the bioaccessibility of the selected phenols. Hydroxytyrosol-O-glucoside and caffeic did not cross Caco-2 cell monolayers. Conversely ferulic acid, identified as the main caffeic acid intestinal metabolite, was absorbed through intestinal cell monolayers (~20%). Interestingly, ß-CD moderately but significantly improved the local absorption of tyrosol and p-coumaric acid (2.3 + 1.4% and 8.5 ± 4.2%, respectively, p < 0.05), even if their final bioavailability (expressed as bioaccessibility × absorption by Caco-2 cells) was not modified (16.2 ± 0.6% vs. 16.8 ± 0.5% for tyrosol and 32.0 ± 3.2% vs. 37.2 ± 3.2% for p-coumaric acid, from pure alperujo and alperujo complexed with ß-CD, respectively). Overall, our results show that ß-CD is an interesting extraction and storage agent for phenolic compounds that does not alter their in vitro bioavailability.

Nutritional Composition and Bioactive Content of Legumes: Characterization of Pulses Frequently Consumed in France and Effect of the Cooking Method.

Pulses display nutritional benefits and are recommended in sustainable diets. Indeed, they are rich in proteins and fibers, and can contain variable amounts of micronutrients. However, pulses also contain bioactive compounds such as phytates, saponins, or polyphenols/tannins that can exhibit ambivalent nutritional properties depending on their amount in the diet. We characterized the nutritional composition and bioactive compound content of five types of prepared pulses frequently consumed in France (kidney beans, white beans, chickpeas, brown and green lentils, flageolets), and specifically compared the effects of household cooking vs. canning on the composition of pulses that can be consumed one way or the other. The contents in macro-, micronutrients, and bioactive compounds highly varied from one pulse to another (i.e., 6.9 to 9.7 g/100 g of cooked product for proteins, 4.6 to 818.9 µg/100 g for lutein or 15.0 to 284.3 mg/100 g for polyphenols). The preparation method was a key factor governing pulse final nutritional composition in hydrophilic compounds, depending on pulse species. Canning led to a greater decrease in proteins, total dietary fibers, magnesium or phytate contents compared to household cooking (i.e., -30%, -44%, -33% and -38%, p < 0.05, respectively, in kidney beans). As canned pulses are easy to use for consumers, additional research is needed to improve their transformation process to further optimize their nutritional quality.

Production of asymmetric oxidative metabolites of [13C]-ß-carotene during digestion in the gastrointestinal lumen of healthy men.

Background: Asymmetric ß-apo-carotenoids (nonvitamin A-active metabolites) of provitamin A carotenoids have been observed in humans, but no study has investigated their formation during digestion. Objective: The aim of this study was to follow the formation and absorption of asymmetric ß-apo-carotenoids during digestion. Design: Healthy men were intragastrically and intraduodenally intubated, and randomly assigned to consume a lipid-rich control meal (n = 3) or a lipid-rich test meal containing 20 mg [13C-10]-ß-carotene (n = 7). Digesta samples were collected over 5 h, and blood collected over 7 h. The triglyceride-rich lipoprotein (TRL) fractions of plasma were also isolated. Lipophilic extracts of digesta, plasma, and TRL were analyzed via a high-performance liquid chromatography-tandem mass spectrometry method developed to identify [13C]-labeled ß-apo-carotenals/carotenone, [13C]-ß-apo-carotenols, and [13C]-ß-apo-carotenoic acids. Results: Relative to [13C]-ß-carotene, [13C]-ß-apo-carotenal levels remained ∼3 orders of magnitude lower throughout digestion (no [13C]-ß-apo-carotenols, or [13C]-ß-apo-carotenoic acids were observed). A mixed model determined relative influence of digesta type and time on digesta metabolite level. Increasing time significantly increased the model levels of digesta [13C]-ß-apo-10',12',14',15-carotenal and [13C]-ß-apo-13-carotenone (P < 0.05) and trended toward decreased [13C]-ß-apo-8'-carotenal (P = 0.0876). Gastric digesta were associated with a significantly higher level of [13C]-ß-apo-8'-carotenal (P = 0.0289), and lower levels of [13C]-ß-apo-12',14',15-carotenal (P < 0.05), relative to duodenal digesta. Anticipated retinoids, but no asymmetric [13C]-ß-apo-carotenals, [13C]-ß-apo-carotenols, or [13C]-ß-apo-carotenoic acids, were observed in the blood or TRL samples. Conclusions: ß-Carotene appears to be robust to digestion, with minor amounts of ß-apo-carotenals/carotenone formed. Absence of asymmetric [13C]-ß-apo-carotenals in plasma and TRL suggests lack of absorption, levels below the limit of detection, lack of stability, or further conversion during the digestive process to as-yet unidentified products. Lack of asymmetric [13C]-ß-apo-carotenals in plasma also suggests a lack of postprandial intestinal BCO2 activity in healthy humans. This trial was registered at clinicaltrials.gov as NCT03492593.

Comparison of the Micellar Incorporation and the Intestinal Cell Uptake of Cholecalciferol, 25-Hydroxycholecalciferol and 1-α-Hydroxycholecalciferol.

In the context of the global prevalence of vitamin D insufficiency, we compared two key determinants of the bioavailability of 3 vitamin D forms with significant biopotencies: cholecalciferol, 25-hydroxycholecalciferol and 1-α-hydroxycholecalciferol. To this aim, we studied their incorporation into synthetic mixed micelles and their uptake by intestinal cells in culture. Our results show that 1-α-hydroxycholecalciferol was significantly more solubilized into mixed micelles compared to the other forms (1.6-fold and 2.9-fold improvement compared to cholecalciferol and 25-hydroxycholecalciferol, respectively). In Caco-2 TC7 cells, the hydroxylated forms were taken up more efficiently than cholecalciferol (p < 0.05), and conversely to cholecalciferol, their uptake was neither SR-BI(Scavenger-Receptor class B type I)- nor NPC1L1 (NPC1 like intracellular cholesterol transporter 1)-dependent. Besides, the apical membrane sodium-bile acid transporter ASBT (Apical Sodium-dependent Bile acid Transporter) was not involved, at least in vitro, in the uptake of any of the three vitamin D forms. Further investigations are needed to identify the uptake pathways of both 1-α-hydroxycholecalciferol and 25-hydroxycholecalciferol. However, considering its high bioavailability, our results suggest the potential interest of using 1-α-hydroxycholecalciferol in the treatment of severe vitamin D deficiency.

A Combination of Single-Nucleotide Polymorphisms Is Associated with Interindividual Variability in Cholecalciferol Bioavailability in Healthy Men.

BACKGROUND: Most people require dietary vitamin 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 (in kg/m2) 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 × 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.

Form of phytosterols and food matrix in which they are incorporated modulate their incorporation into mixed micelles and impact cholesterol micellarization.

SCOPE: The ability of different plant sterols/stanols (PS) mixtures, which differed in the degree of B-ring saturation and aliphatic side chain structure and saturation, to reduce cholesterol (CH) micellarization was explored. METHODS AND RESULTS: Experiments were performed using an in vitro digestion model, synthetic mixed micelles, and pure porcine pancreatic lipases. Sterols were measured by GC-FID. The ability of PS to reduce CH micellarization was dependent on the form of PS and on the type of delivery matrix (low-fat yogurt or olive oil). Long-chain PS esters delivered in the yogurt matrix, and medium chain PS esters delivered in olive oil provided the greatest reduction in CH micellarization. In yogurt, the ability to impair CH micellarization was inversely related (rho = -0.41, p < 0.0005) to PS melting point. In olive oil, the more hydrophobic PS mixtures, i.e. those rich in long-chain PS esters, had the lower ability to impair CH micellarization. CONCLUSIONS: Different forms of PS have a different ability to impair CH micellarization. This ability depends on the transfer efficiency of PS from the food matrix to the micelle, which in turn depends on the melting point and the hydrophobicity of PS and on the delivery food matrix.