Nonextractable polyphenols,usually ignored,are the major part of dietary polyphenols: A study on the Spanish diet

Scope: Dietary polyphenols (PP) can be divided into two groups: extractable polyphenols (EPP) or compounds solubilized by aqueous organic solvents, and nonextractable polyphenols (NEPP) or compounds that remain in their corresponding extraction residues. Most studies on food polyphenols and dietary intakes address exclusively EPP. The objective of this work was to determine the actual amount of PP, including NEPP, in food and in a whole diet. Methods and results: HPLC‐MS analyses were performed to identify EPP in methanol–acetone extracts and NEPP in the acidic hydrolyzates of their extraction residues in cereals, fruits, vegetables, nuts, and legumes. NEPP contents, estimated as hydrolyzable PP plus nonextractable proanthocyanidins (PA), ranged from 880 mg/100 g dry weight in fruits to 210 mg/100 g in cereals and were substantially higher than the contents of EPP. NEPP intake (day/person) in the Spanish diet (942 mg) is higher than EPP intake (258 mg) fruits and vegetables (746 mg) are the major contributors to the total PP intake (1201 mg). Conclusion: Non extractable polyphenols are the major part of dietary polyphenols. The knowledge of intakes and physiological properties of NEPP may be useful for a better understanding of the potential health effects of dietary PP.     

Macromolecular antioxidants or non-extractable polyphenols in fruit and vegetables: Intake in four European countries

Macromolecular antioxidants or non-extractable polyphenols are an emerging and ignored fraction of dietary antioxidants that present differential structural and physiological features as compared with the well-known extractable polyphenols. In this study, the macromolecular antioxidant content and profile were determined by the first time for the 24 most consumed fruit and vegetables in four European countries (France, Germany, The Netherlands and Spain). Results showed that macromolecular antioxidants, made up of hydolysable polyphenols and polymeric proanthocyanidins, are major contributors (mean value 57%) to the total polyphenol content of fruit and vegetables. Macromolecular antioxidant intake from fruit and vegetable determined in the four countries selected was about 200 mg. Spain had the highest daily per capita macromolecular antioxidant intake from fruit, while The Netherlands had the highest intake derived from vegetables. Future studies of plant food macromolecular antioxidant analysis and of dietary intakes in different populations are needed to elucidate the contribution of these macromolecular antioxidants to the health effects associated with fruit and vegetable consumption, and with dietary antioxidant intake.     

Gastrointestinal microbes increase arsenic bioaccessibility of ingested mine tailings using the simulator of the human intestinal microbial ecosystem

It is widely accepted that the use of total metal concentrations in soil overestimates metal risk from human ingestion of contaminated soils. In vitro simulators have been used to estimate the fraction of arsenic present in soil that is bioaccessible in the human digestive track. These approaches assume that the bioaccessible fraction remains constant across soil total metal concentrations and that intestinal microbiota do not contribute to arsenic release. Here, we evaluate both of these assumptions in two size fractions (bulk and <38 microm) of arsenic-rich mine tailings from the Goldenville, Lower Seal Harbour, and Montague Gold Districts, Nova Scotia. These samples were evaluated using an in vitro gastrointestinal model, the Simulator of the Human Intestinal Ecosystem (SHIME). Arsenic bioaccessibility, which ranged between 2 and 20% in the small intestine and 4 and 70% in the colon, was inversely related to total arsenic concentration in the mine tailings. Additionally, arsenic bioaccessibility was greater in the bulk fraction than in the <38 microm fraction in the small intestine and colon while colon microbes increased the bioaccessibility of arsenic in mine tailings. These results suggest that the practice of using a constant percent arsenic bioaccessibility across all metal concentrations in risk assessment should be revisited.     

Bioaccessibility of calcium, iron and zinc from three legume samples

Legumes can be a source of mineral elements but also of antinutritional factors which can affect their absorption. An in vitro method including gastrointestinal digestion was used to estimate mineral bioavailability. Soluble (bioaccessible) and insoluble calcium, iron and zinc from white beans, chickpeas and lentils were determined after gastrointestinal digestion. The influence of the original sample weight on the soluble mineral fraction was also estimated. The results obtained show that white beans are the legumes with the highest bioaccessible calcium and iron contents. Lentils have a high iron content but its bioaccessibility is much lower than that of iron from white beans and chickpeas. An increase in sample weight increases the amount of bioaccessible element available for intake, but the increase is not always proportional.     

The contribution of fruits and vegetables to dietary intake of polyphenols and antioxidant capacity in a Mexican rural diet: Importance of fruit and vegetable variety

There is mounting evidence of the health-protective role of the consumption of fruits and vegetables, which are the major contributors to dietary polyphenol intake. Lack of knowledge about the consumption of phytochemicals in the Mexican diet makes it difficult to evaluate their health significance. The aim of this study was therefore to estimate the contribution of fruit and vegetable consumption to dietary polyphenol intake and dietary antioxidant capacity in a rural population in Mexico. Despite a low intake of fruits and vegetables (< 400 g/day) in the Mexican rural diet, the mean daily intake of dietary polyphenols (> 800 mg/day) and dietary antioxidant capacity (1000-2000 ??mol trolox equivalents/day) from fruits and vegetables was similar to those determined in the Spanish Mediterranean diet. Local fruits and vegetables consumed in the Mexican rural diet are rich in polyphenols with antioxidant properties and are important source of bioactive compounds and dietary fibers. Fruit and vegetable intake needs to be promoted and lifestyle and environmental factors enhanced to improve the health status of obese Mexican rural populations.     

Bioaccessibility and antioxidant activity of phenolic compounds in cooked pulses

The aim of this study was to evaluate the bioaccessibility of polyphenols and antioxidant activity in cooked pulses and to study the effect of cooking on their total phenolic content (TPC) and antioxidant capacity. Cooked faba beans showed the highest TPC, followed by soybeans and lentils or peas. TPC ranged from 10.4 ± 0.2 to 52.9 ± 0.3 mg/100 g and was positively correlated with antioxidant activity. Cooking resulted in increased TPC and antioxidant activity of the methanolic extracts, caused by cell disruption and improved extraction of polyphenols. Although polyphenols were lost in the cooking water, boiled legumes had more polyphenols than those resulting cooking broths. In vitro gastrointestinal digestion resulted in increased TPC and antioxidant capacity of the extracts. Soybeans showed the highest amount of bioaccessible polyphenols. The release of phenolics from cooked legumes was mainly achieved during the intestinal phase. Literature data may underestimate the TPC and antioxidant capacity of pulses.     

The intake of dietary fiber from grape seeds modifies the antioxidant status in rat cecum

The aim of this study was to measure the antioxidant activity and polyphenolic compounds in cecum and feces of rats fed with a grape seed concentrate. The grape concentrate was rich in indigestible compounds (dietary fiber, polyphenols and other associated compounds) which presented significant antioxidant activity. Polyphenols extracted by aqueous–organic solvents (extractable polyphenols, EPs) and non‐extractable polyphenols (NEPs) exhibited high antioxidant capacity as measured by the ABTS method. High correlations were found between antioxidant capacity values and EP (r² = 0.9608) and NEP content (r² = 0.9179). EPs and NEPs exhibited considerable antioxidant activity within the large intestine. Significant antioxidant activity was also found in feces derived from excreted EPs and NEPs. The grape fiber concentrate enhanced the antioxidant status in the large intestine. The antioxidant activity in the intestinal content should be considered when assessing the effects of dietary components on bowel diseases. Copyright © 2005 Society of Chemical Industry     

Bioaccessibility of Ca,Mg, Mn and Cu from whole grain tea-biscuits: Impact of proteins,phytic acid and polyphenols

Levels of some essential minerals (Ca, Mg, Cu and Mn) were determined in ten different types of experimentally prepared hard biscuits. In relation to the wheat flour-based reference sample, other investigated samples were enriched with different ratios of integral raw materials of different origin or various dietary fibers in view of improving their functionality and nutritive quality. The goal of the research was to evaluate enriched biscuits as additional sources of calcium, magnesium, copper and manganese in nutrition and to investigate if the modifications of wheat flour based biscuit composition significantly change the amounts of total and bioaccessible minerals in the final product. Since our results indicated significant changes of mineral bioaccessibility among the samples, obtained results were correlated to the content of proteins, phytic acid and polyphenols for the sake of assessing their impact as limiting factors of mineral bioaccessibility in these types of foods.     

贵州省大米、玉米和辣椒中钙的生物可给性及其膳食营养价值评价

摘 要: 目的 对大米、玉米和辣椒中钙含量进行测定, 探究钙的生物可给性差异及其膳食营养价值。方法 采用分层随机抽样方法, 样本来自贵州省的9个市州。基于火焰原子吸收光谱法测定大米、玉米和辣椒钙含量, 通过体外消化模型(in vitro digestion mode)模拟胃部及肠道消化, 计算大米、玉米和辣椒中钙的生物可给性。结果 辣椒钙含量最高, 为(1799.50±398.70) mg/kg, 其次为玉米, 为(253.41±103.37) mg/kg, 大米最低, 为(69.90±20.53) mg/kg, 3组钙含量差异有统计学意义(F=5249.93, P<0.001)。通过体外消化模型得出大米、玉米和辣椒在胃阶段钙的生物可给性均高于肠阶段(P<0.001); 进一步分析发现, 大米在胃阶段钙的生物可给性(69.72%±10.31%)>玉米(41.40%±11.37%)>辣椒(35.31%±5.46%), 差异有统计学意义(F=192.67, P<0.001); 大米在肠阶段钙的生物可给性(56.69%±12.78%)>辣椒(23.29%±7.66%)>玉米(14.51%±5.19%), 差异有统计学意义(F=294.73, P<0.001)。结论 研究发现大米、玉米和辣椒中钙的膳食营养价值均有限, 不是居民良好的膳食钙来源, 因此, 有必要开展相关的营养教育和干预, 改善居民的饮食结构, 增加牛奶和乳制品的摄入量, 以减少膳食钙摄入量的不足。本研究可为我国居民建立合理饮食结构提供科学依据。     

Bioaccessible and dialysable polyphenols in selected apple varieties following in vitro digestion vs. their native patterns

To assess bioaccessible and dialysable apple polyphenols available for potential uptake by intestinal epithelial cells, an in vitro gastrointestinal (GI) digestion method was developed and main polyphenols investigated by UPLC. Polyphenolic profiles in the gastric medium were similar to those natively occurring in apples; however, bioaccessible polyphenols were at lower concentrations than those in the apples. The polyphenolic profile was altered during intestinal digestion, with a considerable decrease of total polyphenols. Flavan-3-ols were completely unstable in the intestinal medium, owing to their pH sensitivity. In addition, 41-77% of bioaccessible chlorogenic acid, the major abundant hydroxycinnamic acid in apples, was degraded during intestinal digestion, with partial isomerisation to cryptochlorogenic acid and neochlorogenic acid. All polyphenols found in the intestinal medium were dialysable, but were present at lower concentrations, suggesting that dialysable polyphenols can potentially be taken up by the enterocytes. These results highlight that GI digestion may substantially affect native apple-derived polyphenolic patterns and concentrations.     

膳食营养剂对灰褐牛肝菌中镉的生物可给性及其健康风险的影响

聚焦灰褐牛肝菌(Boletus griseus)富镉(Cd)问题,调研了云南3个地区B. griseus样本中的总Cd含量,选取了高、中、低3种不同Cd含量B. griseus样本,建立了一种更易实现、更易量化的体外全仿生消化方法,评价了B. griseus中镉的生物可给性(Cd-BAc),研究了单宁酸、CaCl₂、原花青素、葡萄糖酸锌钙、红毛丹果皮多酚5种膳食营养成分对Cd-BAc的影响,并以此为基础评价了B. griseus中Cd的食用健康风险。结果表明,采集的53个B. griseus样本均具有较高的总Cd含量,在胃部的Cd-BAc为55.30%~59.36%,但是小肠的弱碱近中性环境显著降低了B.griseus中Cd的溶出,Cd-BAc为39.59%~52.86%,大肠菌群发酵进一步降低Cd-BAc至21.41%~25.28%。5种膳食营养剂在胃部对Cd-BAc影响不大,在小肠部和大肠菌群发酵中,均显著降低了Cd-BAc,CaCl₂效果最为显著。以B. griseus中Cd总量计,摄食中镉、高镉含量的B. griseus,Cd对人体的风险熵为2.98和5.13;综合考虑Cd-BAc以及5种膳食营养剂的影响,其风险熵可降低至0~0.37。研究结果表明,B. griseus中Cd的食用健康风险很高,膳食营养剂可通过降低肠道Cd-BAc而调控其对人体的健康风险,因此,膳食营养剂可能是控制高镉食品健康风险的一种有效策略,但是该策略的有效性需要进一步的体内实验验证。     

Verbascosides from olive mill waste water: assessment of their bioaccessibility and intestinal uptake using an in vitro digestion/Caco-2 model system

Olive mill wastewater (OMWW) is an agricultural waste material produced in high quantities in the Mediterranean basin. OMWW may be an inexpensive source of health promoting phytochemicals with potential economic value including many low molecular weight compounds such as verbascosides. While promising as antioxidants in vitro, little information is available on the potential absorption of verbascosides by humans. The main objective of the present study was to characterize the verbascoside content and potential for their bioavailability from a partially purified phenolic fraction (IP) of OMWW. The IP was obtained after ultrafiltration step at 5000 Dalton and gel filtration low-pressure chromatography (LH20) of OMWW. RP-HPLC analysis identified several soluble phenolics compounds including verbascoside and isoverbascoside as major components of OMWW fractions. The potential for bioavailability of these polyphenols was estimated by using both in vitro digestion and Caco-2 human intestinal cell models. In vitro digestive recoveries (bioaccessibility) were found to be 35.5%± 0.55% for verbascoside and 9.2% ± 0.94% for isoverbascoside highlighting potential sensitivity of these phenolics to gastric and small intestinal digestive conditions. Accumulation of verbascosides by highly differentiated Caco-2 monolayers was linear between 10 and 100 μM of verbascoside and isoverbascoside from IP extract. Uptake of verbascoside and isoverbascoside was rapid with peak accumulation occurring after 30 min with total accumulation efficiency of 0.1% and 0.2% providing intracellular levels of 130 and 80 pmol/mg cell protein for verbascoside and isoverbascoside, respectively. Combined, these data suggest that verbascosides present in OMWW are bioaccessible and provides a rationale for subsequent in vivo studies on the bioavailability and bioactivity of OMWW components.     

In vitro bioaccessibility,bioavailability and plasma protein interaction of polyphenols from Annurca apple (M. pumila Miller cv Annurca)

The in vitro bioaccessibility, bioavailability and plasma protein interaction of polyphenols from Annurca apple and other conventional cultivars were evaluated. Salivary digestion concentrated into the medium 27–35% of native apple polyphenols, suggesting the potential bioavailability through the oral mucosal epithelium of significant amounts of bioactive compounds that could be gastric sensitive and/or poorly absorbed in the intestine. Annurca flesh revealed the highest content and provided the best intestinal bioaccessibility and bioavailability of oligomeric procyanidins among all of the apple peel and flesh tested. Since 49.4% of native procyanidins were not absorbed, they are expected to accumulate in the intestinal lumen where a potential inhibition capacity of cellular cholesterol uptake could be assumed. The permeated procyanidins (6.7% of their native pattern, 12.0% of intestinal procyanidins) significantly bound (58.7%) to plasma HDLs, suggesting a major role in cholesterol metabolism. Our results would indicate Annurca apple and its potential nutraceuticals as effective in the regulation of plasma cholesterol levels.     

Estimation of the intake of phenol compounds from virgin olive oil of a population from southern Spain

The objective of the study was to determine the mean polyphenol composition of different varieties of virgin olive oil (VOO) habitually consumed in the region of southern Spain and to estimate the dietary exposure to olive oil polyphenols in that population. There were statistically significant differences in total polyphenols among varieties, with the Picual variety containing the largest amount with a mean value of 591.8 mg kg^–1. The main phenolic compounds found in the VOOs under study were tyrosol and hydroxytyrosol. The highest amounts of both substances were found in Picual olive oils with concentrations of 2.3–6.6 mg kg^?1. The total intake of polyphenols from VOO ranged between 8.2 mg day^–1 (SD = 4.14) for the under 19 year olds and 21.3 mg day^–1 (SD = 3) for the over 50 year olds. Some polyphenols, including tyrosol and hydroxytyrosol, were consumed principally as olive oil. The intake of these compounds in the studied population was in the range of 88.5–237.4 μg day^–1. This has particular importance as recent studies have demonstrated that hydroxytyrosol helps to improve plasma lipids levels and repair oxidative damage related to cardiovascular disease. There was a greater dietary consumption of polyphenols in olive oil among the participants who more closely followed the Mediterranean diet pattern. A higher consumption of olive oil and therefore a greater exposure to polyphenols was observed in females versus males and in participants of normal weight versus those who were overweight. The total intake of polyphenols from VOO significantly increased with higher age, reflecting the greater intake of this oil by older people, who also show a closer adherence to the Mediterranean diet. The over 50-year-old age group showed the greatest consumption of this olive oil and therefore of phenolic compounds, which are healthy protectors in the human diet that contribute to the acknowledged benefits of the Mediterranean diet.     

Influence of mercury bioaccessibility on exposure assessment associated with consumption of cooked predatory fish in Spain

BACKGROUND: Predatory fish tend to accumulate high levels of mercury (Hg). Food safety assessment of these fish has been carried out on the raw product. However, the evaluation of the risk from Hg concentrations in raw fish might be modified if cooking and bioaccessibility (the contaminant fraction that solubilises from its matrix during gastrointestinal digestion and becomes available for intestinal absorption) were taken into account. Data on Hg bioaccessibility in raw predatory fish sold in Spain are scarce and no research on Hg bioaccessibility in cooked fish is available. The aim of the present study was to evaluate Hg bioaccessibility in various kinds of cooked predatory fish sold in Spain to estimate their health risk. RESULTS: Both Hg and bioaccessible Hg concentrations were analysed in raw and cooked fish (swordfish, tope shark, bonito and tuna). There were no changes in Hg concentrations during cooking. However, Hg bioaccessibility decreased significantly after cooking (42 ± 26% in raw fish and 26 ± 16% in cooked fish), thus reducing in swordfish and tope shark the Hg concentration to which the human organism would be exposed. CONCLUSION: In future, cooking and bioaccessibility should be considered in risk assessment of Hg concentrations in predatory fish. Copyright © 2011 Society of Chemical Industry     

Bioaccessible nutrients and bioactive components from fortified products prepared using finger millet (Eleusine coracana)

BACKGROUND: Finger millet (Eleusine coracana), a staple food in semi‐arid parts of the world, is a rich source of nutrients and bioactive components comparable to rice and wheat but with higher fibre content. Unprocessed and processed finger millet (whole flour (WFM), sieved flour (SFM), wafers and vermicelli with altered matrices (added Fe or Zn or reduced fibre)) were analysed for chemical composition, bioaccessible Fe, Zn and Ca, in vitro digestible starch (IVSD) and protein (IVPD) and bioactive components (polyphenols and flavonoids). RESULTS: WFM and SFM flours differed significantly in their composition. Sieving decreased the content of both nutrients and antinutrients in WFM but increased their digestibility/bioaccessibility. WFM products with Zn and Fe showed highest IVPD, whereas SFM products with Fe showed highest IVSD. Products with externally added Fe and Zn showed maximum bioaccessibility of Fe and Zn respectively. WFM had the highest levels of total polyphenols and flavonoids, 4.18 and 15.85 g kg^?1 respectively; however, bioaccessibility was highest in SFM vermicelli. CONCLUSION: The availability of nutrients and bioactive components was influenced by both processing methods and compositional alterations of the food matrix in finger millet products, and bioaccessibility of all constituents was higher in vermicelli (wet matrix) than in wafers (dry matrix). Copyright © 2012 Society of Chemical Industry     

Definition of the Mediterranean diet based on bioactive compounds

Antioxidant (polyphenols and carotenoids) and nonantioxidant (phytosterols) bioactive compounds and dietary fiber may have a significant role in health. The intake of these compounds is strongly linked with the high consumption of fruits, vegetables, and unrefined cereals. A whole-diet approach to these food constituents is intended to render the current definition of Mediterranean diet based on food consumption more comprehensive. The Mediterranean dietary pattern can be characterized by the following four essential dietary indicators: 1) Monounsaturated to saturated fatty acid ratio (range: 1.6 to 2.0); 2) Intake of dietary fiber (41 to 62 g/person/day); 3) Antioxidant capacity of the whole diet (3500 to 5300 trolox equivalent/person/day); 4) Phytosterols intake (370 to 555 mg/person/day). The contribution of foods and beverages to these parameters is described. Spanish National Food Consumption Data for the years 2000 and 1964 were used to quantify the lowest and highest range values. The occurrence of these indicators in the Mediterranean diet has specific characteristics and there is sufficient scientific evidence to support the beneficial health effects.     

Dry-fractionation of wheat bran increases the bioaccessibility of phenolic acids in breads made from processed bran fractions

This study evaluated the potential of using ultra-fine grinding and electrostatic separation of wheat bran as methods to improve the bioaccessibility of para-coumaric acid (pCA), sinapic acid (SA) and ferulic acid (FA) from bran-rich breads. Bran fractions were produced and used to bake white bread, whole-grain bread, and seven different bran-rich breads. The influence of bran particle size and bread composition on the bioaccessibility of pCA, SA and FA was studied using a dynamic computer-controlled in vitro gastro-intestinal model. The amount of bioaccessible phenolic acids was higher in whole-grain bread and bran-rich breads than in white bread, and the finer the bran particles in bran-rich breads, the more bioaccessible the phenolic acids. The highest amounts of bioaccessible phenolic acids were observed for two of the fractions obtained by electrostatic separation of ground bran. Only the free and conjugated phenolic acids forms were found to be bioaccessible, and the bioaccessibility of SA was much higher than that of FA, due to the higher solubility of SA. This study demonstrated that the use of bran fractionation to reduce the particle size, or to include only some parts of the bran in foods, can help developing grain-based products with increased nutritional potential.     

Tannase improves gallic acid bioaccessibility and maintains the quality of mango juice

The effect of tannase on gallic acid (GA) bioaccessibility and auto-oxidative browning of mango juice was investigated. After 2 h of simulated gastric digestion, the concentration of bioaccessible GA increased (P < 0.05) 94.3 ± 7.0% in juice treated with 0.5 U mL⁻¹ tannase while juice not treated with tannase had only a 6.3 ± 3.4% increase in GA. During 2–10 h of simulated intestinal digestion, tannase treated juice continued to have a higher concentration (P < 0.05) of bioaccessible GA in comparison to juice that was not treated with tannase. The use of 167 U 100 mL⁻¹ tannase while processing mango juice did not result in any differences (P < 0.05) in browning measured at 420 nm, yet there was significantly higher (P < 0.05) GA in mango juice post-storage. Processing mango juice with tannase can help improve the bioaccessibility of mango polyphenols without hindering the quality of juice during storage.     

Studies on apple and blueberry fruit constituents: do the polyphenols reach the colon after ingestion?

The aim of our studies was to determine the amount of polyphenols reaching the colon after oral intake of apple juice and blueberries. After a polyphenol-free diet healthy ileostomy volunteers consumed a polyphenol-rich cloudy apple juice while others consumed anthocyanin-rich blueberries. Ileostomy effluent was collected and polyphenols were identified using HPLC-DAD as well as HPLC-ESI-MS/MS; quantification was performed with HPLC-DAD. Most of the orally administered apple polyphenols were absorbed from or metabolized in the small intestine. Between 0 and 33% of the oral dose was recovered in the ileostomy bags with a maximum of excretion after 2 h. A higher amount of the blueberry anthocyanins under study (up to 85%, depending on the sugar moiety) were determined in the ileostomy bags and therefore would reach the colon under physiological circumstances. Such structure-related availability has to be considered when polyphenols are used in model systems to study potential preventive effects in colorectal diseases.