Grapefruit juices impair the bioaccessibility of β-carotene from orange-fleshed sweet potato but not its intestinal uptake by Caco-2 cells

Medium Chain Triglycerides Promote the Uptake of β-Carotene in O/W Emulsions via Intestinal Transporter SR-B1 in Caco-2 Cells

This study aimed to elucidate the impacts of carrier oil types (long chain triglycerides (LCT), medium chain triglycerides (MCT), and orange oil (indigestible oil)) on the micellization and cellular uptake of β-carotene (BC) formulated in O/W emulsions, with an emphasis on the role of intestinal transporters. The micellization and cellular uptake of BC in the gastrointestinal tract were evaluated via an in vitro digestion model and a Caco-2 cell monolayer. And the interactions between lipids and intestinal transporters were monitored by nontargeted lipidomics, RT-PCR, and Western blot. The BC micellization rates followed a decreasing trend in emulsions: corn oil (69.47 ± 4.19%) > MCT (22.22 ± 0.89%) > orange oil (11.01 ± 2.86%), whereas the cellular uptake rate of BC was significantly higher in MCT emulsion (56.30 ± 20.13%) than in corn oil emulsion (14.01 ± 1.04%, p < 0.05). The knockdown of SR-B1 led to a 31.63% loss of BC cellular uptake from MCT micelles but had no effect on corn oil micelles. Lipidomics and transporter analysis revealed that TG (10:0/10:0/12:0) and TG (10:0/12:0/12:0) might be the fingerprint lipids that promoted the cellular absorption of BC-MCT micelles via stimulating the mRNA expression of SR-B1.

In vitro bioaccessibility of vitamin K (phylloquinone and menaquinones) in food and supplements assessed by INFOGEST 2.0 – vit K

Vitamin K describes a group of fat-soluble vitamers namely phylloquinone and menaquinones. The growing evidence for vitamin K's role beyond blood coagulation, and the possible differences between the vitamers are emerging. Knowledge of the content of menaquinones in different food matrixes and the potential differences in bioaccessibility between the vitamin K vitamers and food matrixes are limited. In this study, the bioaccessibility was assessed using the INFOGEST 2.0 static in vitro digestion model optimised by including a Danish standard meal. The presence of the standard meal was crucial to obtaining a robust and stable digestion model. The bioaccessibility of the Danish standard meal, water, vitamin K standards, vitamin K supplements, broccoli, spinach, natto, pasteurised whole egg and canola oil was assessed by three replications. The bioaccessibility was in the range 30%–102%. The lowest bioaccessibility was observed in broccoli while the highest bioaccessibility was found in egg and canola oil. No competition in the bioaccessibility between vitamin K vitamers and vitamin D was observed.

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The INFOGEST 2.0 method was optimised for vitamin K research (INFOGEST 2.0 – vit K).

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INFOGEST 2.0 – vit K includes a standard meal based on a typical Danish meal.

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Addition of the standard meal ensures a stable and concentration independent model.

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The bioaccessibility (bioacc) of PK, MK-4 to MK-10 depended on the food matrix.

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The highest bioacc was found in oil, then supplements, followed by broccoli.

Preventive action of retinoids in metabolic syndrome/type 2 diabetic rats fed with citrus functional food enriched in β-cryptoxanthin

Citrus fruits are known for their beneficial health effects associated with the prevention of metabolic syndrome/type 2 diabetes that is mainly attributed to flavonoids. Few investigations have reported the potential anti-diabetic effects of retinoids from the bioconversion of β-cryptoxanthin (bcx), a citrus carotenoid. Therefore, the present study explored the anti-diabetic effect of a citrus functional food, obtained by membrane eco-technology of a citrus clementina juice, especially enriched in bcx but also in flavonoids and pectin. We assessed the in vivo effect of citrus bcx absorption and its bioconversion into retinoids in metabolic syndrome/type 2 diabetic fructose rats. Fructose-fed rats were used as a prediabetic control, and a prediabetic group was treated with the citrus concentrate for 8 weeks. The citrus-based food treatment improved glucose tolerance, dyslipidemia and blood pressure, in prediabetic rats. Although these effects were in part due to the synergy between enriched phytonutrients (bcx, hesperidin, pectin) of the citrus matrix, the role of bcx and its bioconversion into retinoids were highlighted. We showed that prediabetic rats absorbed less bcx and the bioconversion was less efficient. Bcx from citrus-based food was able to restore vitamin A status in prediabetic rats suggesting that the absorption/bioconversion of bcx may have a key role in improvement of metabolic syndrome/type 2 diabetes.

Iron, Catechin, and Ferulic Acid Inhibit Cellular Uptake of β-Carotene by Reducing Micellization

Green leafy vegetables have low β-carotene bioavailability, which we hypothesized to be, at least in part, due to high contents of fiber, minerals, and phenolics. We investigated the effects of pectin (40-120 μg/mL), iron (50-150 μg/mL), ferulic acid (30-90 μg/mL), and catechin (50-150 μg/mL), in a model system, on β-carotene micellization (in vitro digestion) and intestinal absorption (Caco-2 cell model). Iron, pectin, ferulic acid, and catechin on average reduced ( p < 0.05) β-carotene micellization (1.49 ± 0.05 μmol/L) by 66.9, 59.3, 43.2, and 51.7%, respectively. Iron reduced micellization by precipitating bile salts from solution and ferulic acid and catechin by inhibition of pancreatic lipase. β-Carotene uptake by Caco-2 cells (2.63 ± 0.22%) was reduced ( p < 0.05) by 37.4, 70.1, 77.0, and 75.1%, respectively, when it was digested with pectin, iron, ferulic acid, or catechin. However, when individual test compounds were added to already micellized β-carotene, they did not inhibit β-carotene uptake. The large reductions in β-carotene micellization observed in vitro warrant further investigation in humans using model green leafy vegetable systems to elucidate their relevance under real-life conditions.

Citrus Flavanones Enhance β-Carotene Uptake in Vitro Experiment Using Caco-2 Cell: Structure-Activity Relationship and Molecular Mechanisms

Flavonoids can interfere with the absorption of carotenoids. In this study, the inherent mechanisms of 12 citrus flavanones for β-carotene (Bc) cellular uptake and the structure-activity relationship were investigated. The results showed that multiple hydroxyl groups had the lowest promoting effect. O-Glycosylation at C7 of the A ring led to the greatest promoting effect on Bc absorption. O-Glycosylation at C7 exhibited a strong affinity with the cell membrane and subsequently fluidized the cell membrane. Aglycon molecules significantly induced transient increases of paracellular permeability by decreasing tight junction proteins (ZO-1, claudin-1) expression. In addition, citrus flavanones might enhance scavenger receptor class B type I (SR-BI) expression via their actions as agonists of peroxisome proliferator-activated receptor-gamma (PPARγ). Catechol structure in the B-ring attenuated the activate action of SR-BI expression. The structure-dependent membrane permeability and activation of specific membrane proteins are mechanistically associated with the promoting effect on Bc cellular uptake by citrus flavanones.

Hesperetin and Hesperidin Improved β-Carotene Incorporation Efficiency, Intestinal Cell Uptake, and Retinoid Concentrations in Tissues

Dietary constituents can influence the bioavailability of carotenoids. This study investigated the effect of citrus flavanones on β-carotene (Bc) bioavailability using four experimental models: in vitro digestion procedure, synthetic mixed micelles, Caco-2 cell monolayers, and gavage experiments in mice. The addition of hesperetin (Hes, 25 μM) and hesperidin (Hes-G, 25 μM) standards significantly increased the incorporation efficiency of the Bc standard to 68.7 ± 3.6 and 75.2 ± 7.5% ( p < 0.05), respectively. However, the addition of naringenin (Nar, 25 μM) and naringin (Nar-G, 25 μM) standards significantly reduced the incorporation efficiency of Bc by 23.8 and 26.4%, respectively ( p < 0.05). The increases in scavenger receptor class B type I (SR-BI) expression promoted by citrus flavanones played an important role in Bc cellular absorption in the Caco-2 cell model. Furthermore, after 3 days of gavage, four citrus flavanones (7.5 mg kg^-1 day^-1) increased the retinoid concentrations in tissues; in contrast, after 7 days of gavage, Nar and Nar-G significantly decreased hepatic retinoid concentrations ( p < 0.05). This finding suggested that the incorporation efficiency into micelles was the main step governing carotenoid bioavailability.

Bioaccessibility of Biofortified Sweet Potato Carotenoids in Baby Food: Impact of Manufacturing Process

Orange-fleshed sweet potato (OFSP), a biofortified crop rich in β-carotene, can be used as a component of baby food recipes in order to tackle vitamin A deficiency in children <6 years old. In this work, the impact of formulation (addition of pumpkin, oil, and egg yolk) and industrial heat processing (pasteurization, sterilization) on carotenoid content and bioaccessibility was evaluated in an OFSP-based baby puree. A commercial OFSP baby food product from Brazil and a homemade OFSP puree were used as references. The losses of all-trans-β-carotene ranged from 16 to 21% (pasteurization, homemade) to 32% (sterilization). Because of higher particle sizes and despite a higher content in carotenoids, the homemade puree had a lower bioaccessibility (i.e., micellar transfer using in vitro digestion: 0.50%) compared with the sterilized and commercial purees (5.3-6.2%). Taking into account bioaccessibility and applying a 50% conversion to retinol, a 115 g baby portion of the sterilized OFSP-puree formulated with 2% oil provided 31.4% of the daily vitamin A requirement (RDA) for children under 6 years. In comparison, 115 g of homemade OFSP-puree provided only 3.5% of the RDA. Addition of pumpkin to OFSP did not improve the percentage of RDA. Interestingly, the incorporation of an emulsifier (egg yolk powder) before cooking could improve the percentage of provision by a factor of 2.7. These results showed that reaching a balance between formulation and processing is determinant to maximize carotenoid bioaccessibility of carotenoids from OFSP-based baby food.

Pectin structure and particle size modify carotenoid bioaccessibility and uptake by Caco-2 cells in citrus juices vs. concentrates

Pectin changes from a citrus-based product modify bioaccessibility and carotenoid uptake by intestinal cells.

Consumption of canned citrus fruit meals increases human plasma β-cryptoxanthin concentration, whereas lycopene and β-carotene concentrations did not change in healthy adults

Several studies suggest that β-cryptoxanthin has a greater plasma response from its common food sources than other carotenoids such as β-carotene and lycopene. The hypothesis of this study is that changes in plasma β-cryptoxanthin concentrations will be greater than changes in plasma β-carotene or lycopene concentrations even if these carotenoids are fed in a similar food matrix, such as citrus fruit. We tested this hypothesis by measuring changes in plasma concentrations of β-cryptoxanthin, lycopene, and β-carotene after feeding measured amounts of canned tangerines and pink grapefruit to healthy nonsmoking adult humans. Volunteers served as their own controls and received both citrus fruit treatments randomly. In the first study, 8 subjects ate single meals of 234-304g of tangerines or 60-540g of pink grapefruit. The second study compared changes in plasma carotenoid concentration caused by feeding 234g of tangerines or 540g of pink grapefruit to 11 subjects. Blood was collected 5 times within 24hours after each citrus meal. Carotenoid concentrations were analyzed by reversed-phase high-performance liquid chromatography. Plasma β-cryptoxanthin concentrations increased within 5hours and then stabilized, remaining high throughout the 24hours measured. Plasma concentrations of lycopene and β-carotene did not change. These results show that β-cryptoxanthin concentrations increased after a citrus fruit meal, but lycopene and β-carotene concentrations did not change after a similar citrus fruit meal. These results support our hypothesis that changes in plasma β-cryptoxanthin are greater than changes in plasma lycopene or β-carotene, even when these carotenoids are fed in a similar food matrix.

Effects of Lipids on in Vitro Release and Cellular Uptake of β-Carotene in Nanoemulsion-Based Delivery Systems

β-Carotene (BC) nanoemulsions were successfully prepared by microfluidization. BC micellarization was significantly affected by bile salts and pancreatin concentration. Positive and linear correlation was observed between BC release and bile salts concentration. Pancreatin facilitated BC's release in simulated digestion. Compared to the control (bulk oil) (4.6%), nanoemulsion delivery systems significantly improved the micellarization of BC (70.9%). The amount of BC partitioned into micelles was positively proportional to the length of carrier oils. Unsaturated fatty acid (UFA)-rich oils were better than saturated fatty acid (SFA)-rich oils in transferring BC (p < 0.05). No significant difference was observed between monounsaturated fatty acid (MUFA)-rich oils and polyunsaturated fatty acid (PUFA)-rich oils (p > 0.05). A positive and linear relationship between the degree of lipolysis and the release of BC in vitro digestion was observed. Bile salts showed cytotoxicity to Caco-2 cells below 20 times dilution. BC uptake by Caco-2 cells was not affected by fatty acid (FA) compositions in micelles, but BC uptake was proportional to its concentration in the diluted micelle fraction. The results obtained are beneficial to encapsulate and deliver BC or other bioactive lipophilic carotenoids in a wide range of commercial products.

Carotene reactivity in pink grapefruit juice elucidated from model systems and multiresponse modeling

This study was carried out to assess the impact of pink grapefruit juice composition and structure on the degradation kinetics of lycopene and β-carotene using model systems and multiresponse modeling. Carotenes were heated at four temperatures in their native matrix (juice) or were extracted and incorporated in water/ethanol emulsion systems formulated with or without ascorbic acid or naringin. Kinetic analysis showed that the rate constants and activation energy were lower for lycopene than for β-carotene in the juice, while this trend was inversed in the model system. Multiresponse modeling was used to analyze the role of ascorbic acid and naringin in carotene degradation. Ascorbic acid had a very low impact, while naringin significantly increased the carotene degradation and isomerization rates. We concluded that lycopene was more sensitive to thermal degradation and phytochemical interactions than β-carotene, but this behavior was masked in the fruit juice matrix by better structural protection.

Comparison of content and in vitro bioaccessibility of provitamin A carotenoids in home cooked and commercially processed orange fleshed sweet potato (Ipomea batatas Lam)

Vitamin A deficiency (VAD) remains a public health problem in some regions of Brazil. Increased use of orange-fleshed sweet potato (OFSP) as a source of pro-vitamin A represents a potential strategy for prevention of VAD. We compared the pro-vitamin A content, vitamin A equivalency and bioaccessibility of β-carotene (βC) of two varieties of home cooked OFSP and two commercial sources of processed OFSP. Pro-vitamin A carotenoid content in home cooked, Beauregard variety of OFSP exceeded that in Amelia variety and commercial products for babies. All-trans-βC was the most abundant carotenoid in raw, cooked and commercial OFSP. Boiling and frying OFSP generally decreased total βC. A serving of 100 g FW Beauregard variety of cooked OFSP contained greater than 100% of the estimated average requirement (EAR) for children and women, and up to 92% EAR for lactating women. Although the efficiency of micellarization of all-trans-βC during simulated digestion of OFSP was relatively low (4-8%) and significantly less than for cis-isomers, the quantities of trans-βC incorporated into micelles from boiled Beauregard and fried Amelia varieties exceeded that in micelles generated by digesting commercial OFSP. The bioaccessibility of pro-vitamin A carotenoids in the micelle fraction of digested OFSP was confirmed with differentiated cultures of Caco-2 human intestinal cells. Continued development of OFSP such as the Amelia and Beauregard varieties that are rich in trans-βC and dissemination of best practices for home cooking are encouraged to increase consumption of this food to decrease the risk of vitamin A deficiency in Brazil.