Improving the antinutritional profiles of common beans (Phaseolus vulgaris L.) moderately impacts carotenoid bioaccessibility but not mineral solubility.

Common beans are a common staple food with valuable nutritional qualities, but their high contents in antinutritional factors (ANFs) can decrease the bioavailability of (i) fat-soluble micronutrients including carotenoids and (ii) minerals. Our objective was to select ANF-poor bean lines that would not interfere with carotenoid and mineral bioavailability. To achieve this objective, seeds of commercial and experimental Phaseolus vulgaris L. bean lines were produced for 2 years and the bean's content in ANFs (saponins, phytates, tannins, total polyphenols) was assessed. We then measured carotenoid bioaccessibility and mineral solubility (i.e. the fraction of carotenoid and mineral that transfer into the aqueous phase of the digesta and is therefore absorbable) from prepared beans using in vitro digestion. All beans contained at least 200 mg/100 g of saponins and 2.44 mg/100 g tannins. The low phytic acid (lpa) lines, lpa1 and lpa12 exhibited lower phytate levels (≈ - 80%, p = 0.007 and p = 0.02) than their control BAT-93. However, this decrease had no significant impact on mineral solubility. HP5/1 (lpa + phaseolin and lectin PHA-E free) bean line, induced an improvement in carotenoid bioaccessibility (i.e., + 38%, p = 0.02, and + 32%, p = 0.005, for phytofluene bioaccessibility in 2021 and 2022, respectively). We conclude that decrease in the phytate bean content should thus likely be associated to decreases in other ANFs such as tannins or polyphenols to lead to significant improvement of micronutrient bioaccessibility.

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.

Opposite Effects of the Spinach Food Matrix on Lutein Bioaccessibility and Intestinal Uptake Lead to Unchanged Bioavailability Compared to Pure Lutein.

SCOPE: Food matrix is generally believed to alter carotenoid bioavailability, but its effect on xanthophylls is usually limited. This study thus aims to decipher the digestion-absorption process of lutein in the presence or not of a food matrix. METHODS: Lutein transfer to gastric-like lipid droplets or artificial mixed micelles was assessed when lutein was added to test meals either as a pure molecule ((all-E)-lutein) or in canned spinach ((Z) + (all-E)-lutein). The obtained mixed micelles were delivered to Caco-2 cells to evaluate lutein uptake. Finally postprandial plasma lutein responses were compared in minipigs after the two test meals. RESULTS: Lutein transfer to gastric-like lipid droplets and to mixed micelles was higher when lutein was added in spinach than when it was added as pure lutein (+614% and +147%, respectively, p < 0.05). Conversely, lutein uptake was less effective when micellar lutein was from a meal containing spinach than from a meal containing its pure form (-55%, p < 0.05). In minipigs, postprandial lutein response was delayed with spinach but not significantly different after the two test meals. CONCLUSION: Opposite effects at the micellarization and intestinal cell uptake steps explain the lack of effect of spinach matrix on lutein bioavailability.

Pinoresinol of olive oil decreases vitamin D intestinal absorption.

Enriching oils, such as olive oil, could be one solution to tackle the worldwide epidemic of vitamin D deficiency and to better fit with omega 3 (DHA) recommendations. However, data regarding the interactions occurring at the intestinal level between vitamin D and phenols from olive oil are scarce. We first determined the effect of polyphenols from a virgin olive oil, and a virgin olive oil enriched with DHA, on vitamin D absorption in rats. We then investigated the effects of 3 main olive oil phenols (oleuropein, hydroxytyrosol and pinoresinol) on vitamin D uptake by Caco-2 cells. The presence of polyphenols in the olive oil supplemented with DHA inhibited vitamin D postprandial response in rats (-25%, p<0.05). Similar results were obtained with a mix of the 3 polyphenols delivered to Caco-2 cells. However, this inhibitory effect was due to the presence of pinoresinol only. As the pinoresinol content can highly vary between olive oils, the present results should be taken into account to formulate an appropriate oil product enriched in vitamin D.

ABCG1 is involved in vitamin E efflux.

Vitamin E membrane transport has been shown to involve the cholesterol transporters SR-BI, ABCA1 and NPC1L1. Our aim was to investigate the possible participation of another cholesterol transporter in cellular vitamin E efflux: ABCG1. In Abcgl-deficient mice, vitamin E concentration was reduced in plasma lipoproteins whereas most tissues displayed a higher vitamin E content compared to wild-type mice. α- and γ-tocopherol efflux was increased in CHO cells overexpressing human ABCG1 compared to control cells. Conversely, α- and γ- tocopherol efflux was decreased in ABCG1-knockdown human cells (Hep3B hepatocytes and THP-1 macro- phages). Interestingly, α- and γ-tocopherol significantly downregulated ABCG1 and ABCA1 expression levels in Hep3B and THP-1, an effect confirmed in vivo in rats given vitamin E for 5 days. This was likely due to reduced LXR activation by oxysterols, as Hep3B cells and rat liver treated with vitamin E displayed a significantly reduced content in oxysterols compared to their respective controls. Overall, the present study reveals for the first time that ABCG1 is involved in cellular vitamin E efflux.

Hesperidin increases intestinal ß,ß-carotene 15-15' mono-oxygenase 1 (BCMO1) activity in Mongolian gerbils (Meriones unguiculatus) fed with ß-carotene-free diet.

ß,ß-Carotene 15-15' mono-oxygenase 1 (BCMO1) is a key enzyme in vitamin A (VitA) metabolism in mammals. Dietary compounds, such as carotenoids and polyphenols, were reported to influence BCMO1 activity. The aim of this study was to evaluate the effect of hesperidin (Hes), on the VitA bioefficacy of ß-carotene (Bc) from orange-fleshed sweet potato, using Mongolian gerbils, focussing on BCMO1 activity. Gerbils (n=50) depleted in VitA were divided into five groups fed with basal diet containing 3% white- or orange-fleshed sweet potatoes supplemented or not with Hes. Liver BCMO1 activity was low, with no significant differences between groups. Interestingly, intestinal mucosal BCMO1 activity was significantly higher in the gerbils fed without Bc or VitA than those fed with a VitA/Bc-supplemented diet. Finally, our results show that, under a low VitA status, Hes dramatically stimulated intestinal BCMO1 activity, an effect that could possibly be related to its action as an agonist of PPARγ.

Beta-cryptoxanthin from citrus juices: assessment of bioaccessibility using an in vitro digestion/Caco-2 cell culture model.

Beta-Cryptoxanthin (beta-CX), a provitaminic carotenoid of potential interest for health, is found principally in Citrus fruit in both free and esterified forms. Little is known about the intestinal absorption of beta-CX especially with regard to the esterified forms. The aim of this study was to evaluate the absorption of free and esterified beta-CX using simulated digestion coupled with the Caco-2 model. Bioaccessibility was investigated by measuring the transfer of carotenoids from different citrus juices into micelles using an in vitro digestion system. Then, carotenoid uptake was evaluated by adding carotenoid-rich micelles (from the in vitro digestion) or synthetic micelles (made from synthetic lipids and carotenoids purified from citrus juice) to human intestinal cells (Caco-2 TC7 clone). Our results showed that beta-cryptoxanthin esters (beta-CXE) were partially hydrolysed during the in vitro digestion. The bioaccessibility of free beta-CX measured was significantly higher (40 (SD 1.05) %) than that of beta-carotene (30 (SD 1.9) %) and beta-CXE (16 (SD 1.5) %). In the same way, the incorporation of free beta-CX (27 (SD 1.01) %) into synthetic micelles exceeded (P<0.05) that of beta-carotene (10 (SD 0.7) %) and beta-CXE (8.8 (SD 0.4) %). In the case of micelles from in vitro digestion, the uptake of beta-carotene, free beta-CX and beta-CXE forms by Caco-2 cells was 14.3 (SD 1.8), 3.9 (SD 1.3), and 0.7 (SD 0.08) % respectively. These results showed a preferential uptake by Caco-2 cells of beta-carotene and free beta-CX compared with the two esters of beta-CX.

Differential effect of dietary antioxidant classes (carotenoids, polyphenols, vitamins C and E) on lutein absorption.

Lutein is assumed to protect the human retina from blue light and oxidative stress and diminish the incidence of age-related macular degeneration. This antioxidant is commonly ingested with other dietary antioxidants. The aim of the present study was to assess whether the main dietary antioxidants, i.e. carotenoids, polyphenols and vitamins C and E, affect lutein absorption. We measured the effect of adding a mixture of antioxidants (500 mg vitamin C, 67 mg (100 IU) vitamin E and 1 g polyphenols) to a lutein-containing meal (18 mg) on the postprandial lutein response in the chylomicron-rich fraction in eight healthy men. Lutein response was weakest (-23 %; P=0 x 07) after ingestion of the meal containing antioxidants (21 x 9 (sem 4 x 6) v. 28 x 4 (sem 7 x 2) nmol x h/l). To assess the effect of each class of antioxidants and potential interactions, we subsequently evaluated the effect of various combinations of antioxidants on lutein uptake by human intestinal Caco-2 TC-7 cells. A full factorial design showed that both a mixture of polyphenols (gallic acid, caffeic acid, (+)-catechin and naringenin) and a mixture of carotenoids (lycopene plus beta-carotene) significantly (P<0 x 05) impaired lutein uptake by (-10 to-30 %), while vitamins C and E had no significant effect. Subsequent experiments showed that the aglycone flavanone naringenin was the only polyphenol responsible for the effect of the polyphenol mixture, and that the carotenoid effect was not carotenoid species-dependent. Taken together, the present results suggest that lutein absorption is not markedly affected by physiological concentrations of vitamins C and E but can be impaired by carotenoids and naringenin

Bioaccessibility of carotenoids and vitamin E from their main dietary sources.

Vitamin E and carotenoids are fat-soluble microconstituents that may exert beneficial effects in humans, including protection against cancer, cardiovascular diseases, and age-related eye diseases. Their bioavailability is influenced by various factors including food matrix, formulation, and food processing. Since human studies are labor-intensive, time-consuming, and expensive, the in vitro model used in this study is increasingly being used to estimate bioaccessibility of these microconstituents. However, the ability of this model to predict bioavailability in a healthy human population has not yet been verified. The first aim of this study was to validate this model by comparing model-derived bioaccessibility data with (i) human-derived bioaccessibility data and (ii) published mean bioavailability data reported in studies involving healthy humans. The second aim was to use it to measure alpha- and gamma-tocopherol, beta-carotene, lycopene, and lutein bioaccessibility from their main dietary sources. Bioaccessibility as assessed with the in vitro model was well correlated with human-derived bioaccessibility values (r = 0.90, p < 0.05), as well as relative mean bioavailability values reported in healthy human groups (r = 0.98, p < 0.001). The bioaccessibility of carotenoids and vitamin E from the main dietary sources was highly variable, ranging from less than 0.1% (beta-carotene from raw tomato) to almost 100% (alpha-tocopherol from white bread). Bioaccessibility was dependent on (i) microconstituent species (lutein > beta-carotene and alpha-carotene > lycopene and alpha-tocopherol generally > gamma-tocopherol), (ii) food matrix, and (iii) food processing.

Scavenger receptor class B type I (SR-BI) is involved in vitamin E transport across the enterocyte.

Although cellular uptake of vitamin E was initially described as a passive process, recent studies in the liver and brain have shown that SR-BI (scavenger receptor class B type I) is involved in this phenomenon. As SR-BI is expressed at high levels in the intestine, the present study addressed the involvement of SR-BI in vitamin E trafficking across enterocytes. Apical uptake and efflux of the main dietary forms of vitamin E were examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium. (R,R,R)-gamma-tocopherol bioavailability was compared between wild-type mice and mice overexpressing SR-BI in the intestine. The effect of vitamin E on enterocyte SR-BI mRNA levels was measured by real-time quantitative reverse transcription-PCR. Concentration-dependent curves for vitamin E uptake were similar for (R,R,R)-alpha-, (R,R,R)-gamma-, and dl-alpha-tocopherol. (R,R,R)-alpha-tocopherol transport was dependent on incubation temperature, with a 60% reduction in absorption at 4 degrees C compared with 37 degrees C (p < 0.05). Vitamin E flux in enterocytes was directed from the apical to the basal side, with a relative 10-fold reduction in the transfer process when measured in the opposite direction (p < 0.05). Co-incubation with cholesterol, gamma-tocopherol, or lutein significantly impaired alpha-tocopherol absorption. Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 80% of vitamin E uptake and up to 30% of apical vitamin E efflux (p < 0.05), and similar results were obtained for (R,R,R)-gamma-tocopherol. SR-BI mRNA levels were not significantly modified after a 24-h incubation of Caco-2 cells with vitamin E. Finally, (R,R,R)-gamma-tocopherol bioavailability was 2.7-fold higher in mice overexpressing SR-BI than in wild-type mice (p < 0.05). The present data show for the first time that vitamin E intestinal absorption is, at least in part, mediated by SR-BI.

Enrichment of tomato paste with 6% tomato peel increases lycopene and beta-carotene bioavailability in men.

A high intake of tomato products is associated with a lower incidence of upper aerodigestive tract and prostate cancers. This beneficial effect might be explained by a higher intake of carotenoids such as lycopene and/or beta-carotene. Because tomato peels, usually eliminated during tomato processing, are a valuable source of these carotenoids, we designed a study to examine whether a tomato paste enriched in tomato peels (ETP, 6% peel) increases the absorption of these carotenoids compared to a classically made tomato paste (CTP). Carotenoid bioaccessibility was evaluated using an in vitro digestion model by measuring the amount of carotenoids transferred from the pastes to micelles. Carotenoid absorption by human intestinal cells (Caco-2) was evaluated after the addition of carotenoid-rich micelles (obtained from the in vitro digestion of the 2 pastes). Carotenoid bioavailability in humans was assessed by measuring chylomicron carotenoid responses in a postprandial experiment in which 8 healthy men consumed 2 meals containing either the ETP or the CTP. ETP contained 47.6 mg lycopene (58% more than CTP) and 1.75 mg beta-carotene (99% more than CTP) per 100 g of paste. In micelles, 30% more lycopene and 81% more beta-carotene were recovered after ETP than after CTP in vitro digestion. The amount of carotenoids absorbed by Caco-2 cells was 75% greater (P < or = 0.05) for lycopene and 41% greater (P < or = 0.05) for beta-carotene after the addition of micelles from ETP than from CTP. After ETP intake the chylomicron beta-carotene response was 74% greater than after CTP intake, and the lycopene response tended to be greater (34.1%, P = 0.093). Peel enrichment of tomato paste with tomato peel is an interesting option for increasing lycopene and beta-carotene intakes.