β-lactoglobulin as a vector for β-carotene food fortification

Inhibitory effects of chlorophyll pigments on the bioaccessibility of β-carotene: Influence of chlorophyll structure and oil matrix

Chlorophylls and β-carotene are fat-soluble phytochemicals in daily diets, while their bioaccessibility interaction remains unknown. Eight dietary chlorophylls and their derivatives (chlorophyll a, chlorophyll b, pheophytin a, pheophytin b, chlorophyllide a, chlorophyllide b, pheophorbide a, pheophorbide b) were combined with β-carotene in six different oil matrices (corn oil, coconut oil, medium-chain triglycerides, peanut oil, olive oil and fish oil) and were subjected to in vitro digestion. Generally, chlorophylls significantly decreased β-carotene bioaccessibility by competitive incorporation into micelles. Dephytylated chlorophylls had a greater inhibitory effect on the micellarization and bioaccessibility of β-carotene compared to phytylated chlorophylls. In their co-digestion system, olive oil group exhibited the smallest particle size and biggest zeta potential in both digesta and micelles. For chlorophylls, the phytol group and their levels are key factors, which was also buttressed by the mice model where additional supplementation of pheophorbide a significantly hindered the accumulation of β-carotene and retinoids compounds.

Carotenoids and Their Health Benefits as Derived via Their Interactions with Gut Microbiota

Carotenoids have been related to a number of health benefits. Their dietary intake and circulating levels have been associated with a reduced incidence of obesity, diabetes, certain types of cancer, and even lower total mortality. Their potential interaction with the gut microbiota (GM) has been generally overlooked but may be of relevance, as carotenoids largely bypass absorption in the small intestine and are passed on to the colon, where they appear to be in part degraded into unknown metabolites. These may include apo-carotenoids that may have biological effects because of higher aqueous solubility and higher electrophilicity that could better target transcription factors, i.e., NF-κB, PPARγ, and RAR/RXRs. If absorbed in the colon, they could have both local and systemic effects. Certain microbes that may be supplemented were also reported to produce carotenoids in the colon. Although some bactericidal aspects of carotenoids have been shown in vitro, a few studies have also demonstrated a prebiotic-like effect, resulting in bacterial shifts with health-associated properties. Also, stimulation of IgA could play a role in this respect. Carotenoids may further contribute to mucosal and gut barrier health, such as stabilizing tight junctions. This review highlights potential gut-related health-beneficial effects of carotenoids and emphasizes the current research gaps regarding carotenoid-GM interactions.

Fat-soluble vitamin and phytochemical metabolites: Production, gastrointestinal absorption, and health effects

Consumption of diets rich in fruits and vegetables, which provide some fat-soluble vitamins and many phytochemicals, is associated with a lower risk of developing certain degenerative diseases. It is well accepted that not only the parent compounds, but also their derivatives formed upon enzymatic or nonenzymatic transformations, can produce protective biological effects. These derivatives can be formed during food storage, processing, or cooking. They can also be formed in the lumen of the upper digestive tract during digestion, or via metabolism by microbiota in the colon. This review compiles the known metabolites of fat-soluble vitamins and fat-soluble phytochemicals (FSV and FSP) that have been identified in food and in the human digestive tract, or could potentially be present based on the known reactivity of the parent compounds in normal or pathological conditions, or following surgical interventions of the digestive tract or consumption of xenobiotics known to impair lipid absorption. It also covers the very limited data available on the bioavailability (absorption, intestinal mucosa metabolism) and summarizes their effects on health. Notably, despite great interest in identifying bioactive derivatives of FSV and FSP, studying their absorption, and probing their putative health effects, much research remains to be conducted to understand and capitalize on the potential of these molecules to preserve health.

Proteins involved in fat-soluble vitamin and carotenoid transport across the intestinal cells: New insights from the past decade

It is now well established that vitamins D, E, and K and carotenoids are not absorbed solely through passive diffusion. Broad-specificity membrane transporters such as SR-BI (scavenger receptor class B type I), CD36 (CD36 molecule), NPC1L1 (Niemann Pick C1-like 1) or ABCA1 (ATP-binding cassette A1) are involved in the uptake of these micronutrients from the lumen to the enterocyte cytosol and in their secretion into the bloodstream. Recently, the existence of efflux pathways from the enterocyte back to the lumen or from the bloodstream to the lumen, involving ABCB1 (P-glycoprotein/MDR1) or the ABCG5/ABCG8 complex, has also been evidenced for vitamins D and K. Surprisingly, no membrane proteins have been involved in dietary vitamin A uptake so far. After an overview of the metabolism of fat-soluble vitamins and carotenoids along the gastrointestinal tract (from the mouth to the colon where interactions with microbiota may occur), a focus is placed on the identified and candidate proteins participating in the apical uptake, intracellular transport, basolateral secretion and efflux back to the lumen of fat-soluble vitamins and carotenoids in enterocytes. This review also highlights the mechanisms that remain to be identified to fully unravel the pathways involved in fat-soluble vitamin and carotenoid intestinal absorption.

Potential uses of milk proteins as encapsulation walls for bioactive compounds: A review

Milk proteins have received much awareness due to their bioactivity. However, their encapsulation functions have not attracted enough attention. Milk proteins as encapsulation walls can increase the bioavailability of bioactive compounds. As the benefits of bioactive compounds are critically determined by bioavailability, the effect of interactions between milk proteins and active substances is a critical topic. In the present review, we summarize the effects of milk proteins as encapsulation walls on the bioavailability of active substances with a special focus. The methods and mechanisms of interactions between milk proteins and active substances are also discussed. The evidence collected in the present review suggests that when active substances are encapsulated by milk proteins, the bioavailability of active substances can be significantly affected. This review also provides valuable guidelines for the use of milk protein-based microcarriers.

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.

The non-covalent interactions between whey protein and various food functional ingredients

In daily diet, Whey protein (WP) is often coexisted with various Food functional ingredients (FFI) such as proteins, polyphenols, polysaccharides and vitamins, which inevitably affect or interact with each other. Generally speaking, they may be interact by two different mechanisms: non-covalent and covalent interactions, of which the former is more common. We reviewed the non-covalent interactions between WP and various FFI, explained the effect of each WP-FFI interaction, and provided possible applications of WP-FFI complex in the food industry. The biological activity, physical and chemical stability of FFI, and the structure and functionalities of WP were enhanced through the non-covalent interactions. The development of non-covalent interactions between WP and FFI provides opportunities for the design of new ingredients and biopolymer complex, which can be applied in different fields. Future research will further focus on the influence of external or environmental factors in the food system and processing methods on interactions.

Influence of Proteins on the Absorption of Lipophilic Vitamins, Carotenoids and Curcumin - A Review

While proteins have been widely used to encapsulate, protect, and regulate the release of bioactive food compounds, little is known about the influence of co-consumed proteins on the absorption of lipophilic constituents following digestion, such as vitamins (A, D, E, K), carotenoids, and curcumin. Their bioavailability is often low and very variable, depending on the food matrix and host factors. Some proteins can act as emulsifiers during digestion. Their liberated peptides have amphiphilic properties that can facilitate the absorption of microconstituents, by improving their transition from lipid droplets into mixed micelles. Contrarily, the less well digested proteins could negatively impinge on enzymatic accessibility to the lipid droplets, slowing down their processing into mixed micelles and entrapping apolar food compounds. Interactions with mixed micelles and proteins are also plausible, as shown earlier for drugs. This review focuses on the ability of proteins to act as effective emulsifiers of lipophilic vitamins, carotenoids, and curcumin during digestion. The functional properties of proteins, their chemical interactions with enzymes and food constituents during gastro-intestinal digestion, potentials and limitations for their use as emulsifiers are emphasized and data from human, animal, and in vitro trials are summarized.

Evaluation of Cellular Absorption and Metabolism of β-Carotene Loaded in Nanocarriers after In Vitro Digestion

Three protein emulsifiers encapsulating β-carotene (BC) with accompanying lipids into nanoemulsions (NEs) or without lipids into nanoparticles (NPs) were fabricated to study the effect of the type of interfacial protein on carrier design and the structure remodeling during digestion on the overall uptake and metabolism of BC in Caco-2 cells. BC-loaded micelles and micellar-like aggregates were collected after in vitro digestion and applied to Caco-2 cell monolayers. The digestion process significantly enhanced the cellular uptake of BC by 1.2-2.2 times and 4.1-8.2 times loaded in NEs and NPs, respectively. Whey protein isolate-based carriers improved the absorption but decreased the metabolism of BC to retinyl palmitate. The presence of lipids was found to improve metabolism and aid the transport of retinoids to the basolateral side of Caco-2 monolayers. Understanding the transportation behavior of the protein-based nanocarries after digestion may contribute to the design of biosafe carriers with higher bioavailability to deliver lipophilic nutrients.

Using black soldier fly larvae reared on fruits and vegetables waste as a sustainable dietary source of provitamin a carotenoids

We showed that black soldier fly larvae reared on fruits and vegetables rich in provitamin A carotenoids can accumulate significant amounts of these vitamin A precursors. Using a simulated gastro-intestinal digestion model, we demonstrated that α- and β-carotene from the larvae are as bioaccessible as from the fruits and vegetables they were reared on. We calculated that provitamin A carotenoid-rich larvae have the capacity to provide more vitamin A than fruits and vegetables rich in these molecules. Remarkably, the incorporation of usual quantities of these larvae in feed could cover the needs of several production animals for this vitamin. Thus, our findings suggest that rearing black soldier fly larvae on by-products or waste rich in provitamin A carotenoids could be a sustainable strategy to recycle a fraction of vitamin A back into the food chain and could represent a new approach to fight against vitamin A deficiency.

Novel strategy for enhancing the color intensity of β-Carotene: Enriching onto the oil-water interface

A novel strategy to enhance the color intensity of β-carotene (BC), namely, "interfacial enriching", was developed in this work. As the sole emulsifier in W/O emulsion, BC particles were enriched onto the droplet surface through emulsifying process. By increasing the concentration of BC in oil phase from 1 mg/g to 5 mg/g, the average droplet size of the emulsion decreased from 92.2 ± 5.1 μm to 34.0 ± 5.4 μm. Too low (e.g. ≤ 1 mg/g) or too high (e.g. ≥25 mg/g) concentration of BC in the oil phase yielded an insufficient coverage or flocculation of the droplets. By enriching onto the interface, the color intensity of BC were enhanced apparently at the reflectance wavelength ranging from 500 nm to 700 nm, compared with that of the BC encapsulated within the emulsion droplets. This enhancement was due to the higher availability of incident light for the BC particles on the interface than that of the BC particles buried inside the droplets.

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

The mechanisms of main tomato carotenes (phytoene, phytofluene, lycopene and β-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 β-carotene (areas under the curve of 0.76 ± 0.09 vs. 0.30 ± 0.05, 0.09 ± 0.05 and 0.08 ± 0.01 μmol/L·h for phytofluene, phytoene, lycopene and β-carotene, respectively). β-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.

Mechanisms of Carotenoid Intestinal Absorption: Where Do We Stand?

A growing literature is dedicated to the understanding of carotenoid beneficial health effects. However, the absorption process of this broad family of molecules is still poorly understood. These highly lipophilic plant metabolites are usually weakly absorbed. It was long believed that β-carotene absorption (the principal provitamin A carotenoid in the human diet), and thus all other carotenoid absorption, was driven by passive diffusion through the brush border of the enterocytes. The identification of transporters able to facilitate carotenoid uptake by the enterocytes has challenged established statements. After a brief overview of carotenoid metabolism in the human upper gastrointestinal tract, a focus will be put on the identified proteins participating in the transport and the metabolism of carotenoids in intestinal cells and the regulation of these processes. Further progress in the understanding of the molecular mechanisms regulating carotenoid intestinal absorption is still required to optimize their bioavailability and, thus, their health effects.

Aggregates of octenylsuccinate oat β-glucan as novel capsules to stabilize curcumin over food processing, storage and digestive fluids and to enhance its bioavailability

Self-aggregates of octenylsuccinate oat β-glucan (A_OSG) have been verified as nanocapsules to load curcumin, a representative of hydrophobic phytochemicals. This study primarily investigated the stability of curcumin-loaded A_OSGs over food processing, storage and digestive fluids. Curcumin in A_OSGs showed better stability over storage and thermal treatment than its free form. Curcumin loaded in A_OSGs stored at 4 °C in the dark exhibited higher stability than that at higher temperatures or exposed to light. Approximately 18% of curcumin was lost after five freeze-thaw cycles. Curcumin in A_OSG was more stable than its free form in mimetic intestinal fluids, attesting to the effective protection of A_OSG for curcumin over digestive environments. When curcumin-loaded A_OSG travelled across mimetic gastric and intestinal fluids, curcumin was tightly accommodated in the capsule, while it rapidly escaped as the capsule reached the colon. Interestingly, the curcumin loaded in A_OSG generated higher values of C_max and area under the curve than did its free counterpart. These observations showed that A_OSG is a powerful vehicle for stabilizing hydrophobic phytochemicals in food processing and storage, facilitating their colon-targeted delivery and enhancing their bioavailability.

Retinoic acid prevents immunogenicity of milk lipocalin Bos d 5 through binding to its immunodominant T-cell epitope

The major cow’s milk allergen Bos d 5 belongs to the lipocalin protein family, with an intramolecular pocket for hydrophobic ligands. We investigated whether Bos d 5 when loaded with the active vitamin A metabolite retinoic acid (RA), would elicit differential immune responses compared to the unloaded state. By in silico docking an affinity energy of −7.8 kcal/mol was calculated for RA into Bos d 5. Loading of RA to Bos d 5 could be achieved in vitro, as demonstrated by ANS displacement assay, but had no effect on serum IgE binding in tolerant or challenge-positive milk allergic children. Bioinformatic analysis revealed that RA binds to the immunodominant T-cell epitope region of Bos d 5. In accordance, Bos d 5 significantly suppressed the CD3+ CD4+ cell numbers, proliferative response and IL-10, IL-13 and IFN-γ secretion from stimulated human PBMCs only when complexed with RA. This phenomenon was neither associated with apoptosis of T-cells nor with the activation of Foxp3+ T-cells, but correlated likely with enhanced stability to lysosomal digestion due to a predicted overlap of Cathepsin S cleavage sites with the RA binding site. Taken together, proper loading of Bos d 5 with RA may suppress its immunogenicity and prevent its allergenicity.

Development of β-Carotene-Loaded Organogel-Based Nanoemulsion with Improved In Vitro and In Vivo Bioaccessibility

β-Carotene (BC), a naturally occurring lipophilic carotenoid, is beneficial for human health. However, its water solubility and bioavailability are low. In this study, organogel-based nanoemulsion was successfully prepared to improve the loading amount, solubility, and bioavailability of BC. Corn oil was selected as the oil phase for the organogel as a result of the greatest release amount of BC. Tween 20 was optimized as the emulsifier based on the highest extent of lipolysis and BC bioaccessibility. The nanoemulsion was a better alternative than the organogel according to both the extent of lipolysis and BC bioaccessibility. Cellular uptake of BC was significantly improved through organogel-based nanoemulsion compared to BC suspension. Caveolae-/lipid-raft-mediated route was the main endocytosis pathway. Pharmacokinetic results confirmed that the in vivo bioavailability of BC in nanoemulsion was 11.5-fold higher than that of BC oil. The information obtained suggested that organogel-based nanoemulsion may be an effective encapsulation system for delivery of insoluble and indigestible bioactive compounds.

Genetic Variations Associated with Vitamin A Status and Vitamin A Bioavailability

Blood concentration of vitamin A (VA), which is present as different molecules, i.e., mainly retinol and provitamin A carotenoids, plus retinyl esters in the postprandial period after a VA-containing meal, is affected by numerous factors: dietary VA intake, VA absorption efficiency, efficiency of provitamin A carotenoid conversion to VA, VA tissue uptake, etc. Most of these factors are in turn modulated by genetic variations in genes encoding proteins involved in VA metabolism. Genome-wide association studies (GWAS) and candidate gene association studies have identified single nucleotide polymorphisms (SNPs) associated with blood concentrations of retinol and β-carotene, as well as with β-carotene bioavailability. These genetic variations likely explain, at least in part, interindividual variability in VA status and in VA bioavailability. However, much work remains to be done to identify all of the SNPs involved in VA status and bioavailability and to assess the possible involvement of other kinds of genetic variations, e.g., copy number variants and insertions/deletions, in these phenotypes. Yet, the potential usefulness of this area of research is exciting regarding the proposition of more personalized dietary recommendations in VA, particularly in populations at risk of VA deficiency.

Development, Quantification, Method Validation, and Stability Study of a Novel Fucoxanthin-Fortified Milk

To extend the scope of application of fucoxanthin, a marine carotenoid, whole milk (WM) and skimmed milk (SM) were fortified with fucoxanthin isolated from the microalga Phaeodactylum tricornutum to a final 8 μg/mL milk solution concentration. Using these liquid systems, a fucoxanthin analysis method implementing extraction and HPLC-DAD was developed and validated by accuracy, precision, system suitability, and robustness tests. The current method demonstrated good linearity over the range of 0.125-100 μg/mL fucoxanthin with R(2) = 1.0000, and all validation data supported its adequacy for use in fucoxanthin analysis from milk solution. To investigate fucoxanthin stability during milk production and distribution, fucoxanthin content was examined during storage, pasteurization, and drying processes under various conditions. Fucoxanthin in milk solutions showed better stabilizing effect in 1 month of storage period. Degradation rate constant (k) on fucoxanthin during this storage period suggested that fucoxanthin stability might be negatively correlated with decrease of temperature and increase of protein content such as casein and whey protein in milk matrix. In a comparison between SM and WM, fucoxantin in SM always showed better stability than that in WM during storage and three kinds of drying processes. This effect was also deduced to relate with protein content. In the pasteurization step, >91% of fucoxanthin was retained after three pasteurization processes even though the above trend was not found. This study demonstrated for the first time that milk products can be used as a basic food matrix for fucoxanthin application and that protein content in milk is an important factor for fucoxanthin stability.

Designing food delivery systems: challenges related to the in vitro methods employed to determine the fate of bioactives in the gut

This review discussesin vitroavailable approaches to study delivery and uptake of bioactive compounds and the associated challenges.