Dietary fiber, the evolution of the human diet and coronary heart disease

Interactions in Aqueous Mixtures of Cationic Hydroxyethyl Cellulose and Different Anionic Bile Salts

It is known that the reduction of blood cholesterol can be accomplished through foods containing a large number of dietary fibers; this process is partially related to the binding of bile salt to fibers. To gain new insights into the interactions between dietary fibers and bile salts, this study investigates the interactions between cationic hydroxyethyl cellulose (catHEC) and sodium deoxycholate (NaDC) or sodium cholate (NaC), which have a similar structure. Turbidity measurements reveal strong interactions between catHEC and NaDC, and under some conditions, macroscopic phase separation occurs. In contrast, the interactions with NaC are weak. At a catHEC concentration of 2 wt %, incipient phase separation is approached at concentrations of NaC and NaDC of 32.5 and 19.3 mM, respectively. The rheological results show strong interactions and a prominent viscosification effect for the catHEC/NaDC system but only moderate interactions for the catHEC/NaC system. Both cryogenic transmission electron microscopy and small-angle X-ray scattering results display fundamental structural differences between the two systems, which may explain the stronger interactions in the presence of NaDC. The surmise is that the extended structures formed in the presence of NaDC can easily form connections and entanglements in the network.

Dietary fiber in bakery products: Source, processing, and function

Bakery products are prevalently consumed foods in the world, and they have been regarded as convenient dietary vehicles for delivering nutritive ingredients into people's diet, of which, dietary fiber (DF) is one of the most popular items. The food industry attempts to produce fiber-enriched bakery products with both increasing nutritional value and appealing palatability. As many new sources of DFs become available, and consumers are moving towards healthier diets, studies of using these DFs as functional ingredients in baked goods are becoming vast. Besides, the nutrition value of DF is commonly accepted, and many investigations have also revealed the health benefits of fiber-enriched bakery products. Thus, this chapter presents an overview of (1) trends in supplementation of DF from various sources, (2) impact of DF on dough processing, quality and physiological functionality of bakery products, and (3) technologies used to improve the compatibility of DF in bakery products.

Biomimetic cellulose-based superabsorbent hydrogels for treating obesity

In the treatment of obesity, nutritional and behavioral modifications are difficult to implement and maintain. Since vegetable consumption is a fundamental part of many dietary interventions and daily nutrient requirements, we developed a novel cellulose-based superabsorbent hydrogel (CB-SAH) platform, inspired by the composition and mechanical properties of raw vegetables, as a mechanobiological therapy. The CB-SAHs properties were studied in a simulated gastrointestinal environment, while their impact on gut tissue was investigated by an ex vivo organ culture (EVOC) model. Functional fibers and raw vegetables were used as reference. CB-SAHs demonstrated orders of magnitude higher elasticity in comparison to the tested functional fibers, however performed similar to the tested raw vegetables. Notably, the biomimetic CB-SAHs with elasticity levels similar to raw vegetables showed benefits in preserving and regulating the gut tissue in the EVOC model. Non-systemic oral mechanotherapeutics based on this technology were advanced through clinical studies, with a first product cleared as an aid for weight management in the US and Europe.

Human Fecal Metabolome Reflects Differences in Body Mass Index, Physical Fitness, and Blood Lipoproteins in Healthy Older Adults

This study investigated how body mass index (BMI), physical fitness, and blood plasma lipoprotein levels are related to the fecal metabolome in older adults. The fecal metabolome data were acquired using proton nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry on 163 healthy older adults (65-80 years old, 80 females and 83 males). Overweight and obese subjects (BMI ≥ 27) showed higher levels of fecal amino acids (AAs) (valine, alanine, and phenylalanine) compared to normal-weight subjects (BMI ≤ 23.5). Adults classified in the high-fitness group displayed slightly lower concentrations of fecal short-chain fatty acids, propionic acid, and AAs (methionine, leucine, glutamic acid, and threonine) compared to the low-fitness group. Subjects with lower levels of cholesterol in low-density lipoprotein particles (LDLchol, ≤2.6 mmol/L) displayed higher fecal levels of valine, glutamic acid, phenylalanine, and lactic acid, while subjects with a higher level of cholesterol in high-density lipoprotein particles (HDLchol, ≥2.1 mmol/L) showed lower fecal concentration of isovaleric acid. The results from this study suggest that the human fecal metabolome, which primarily represents undigested food waste and metabolites produced by the gut microbiome, carries important information about human health and should be closely integrated to other omics data for a better understanding of the role of the gut microbiome and diet on human health and metabolism.

Wheat bran, as the resource of dietary fiber: a review

Wheat bran is a major by-product of white flour milling and had been produced in large quantities around the world; it is rich in dietary fiber and had already been used in many products such as whole grain baking or high dietary fiber addition. It has been confirmed that a sufficient intake of dietary fiber in wheat bran with appropriate physiological functions is beneficial to human health. Wheat bran had been considered as the addition with a large potential for improving the nutritional condition of the human body based on the dietary fiber supplement. The present review summarized the available information on wheat bran related to its dietary fiber functions, which may be helpful for further development of wheat bran as dietary fiber resource.

Advances in research on the carrot, an important root vegetable in the Apiaceae family

Carrots (Daucus carota L.), among the most important root vegetables in the Apiaceae family, are cultivated worldwide. The storage root is widely utilized due to its richness in carotenoids, anthocyanins, dietary fiber, vitamins and other nutrients. Carrot extracts, which serve as sources of antioxidants, have important functions in preventing many diseases. The biosynthesis, metabolism, and medicinal properties of carotenoids in carrots have been widely studied. Research on hormone regulation in the growth and development of carrots has also been widely performed. Recently, with the development of high-throughput sequencing technology, many efficient tools have been adopted in carrot research. A large amount of sequence data has been produced and applied to improve carrot breeding. A genome editing system based on CRISPR/Cas9 was also constructed for carrot research. In this review, we will briefly summarize the origins, genetic breeding, resistance breeding, genome editing, omics research, hormone regulation, and nutritional composition of carrots. Perspectives about future research work on carrots are also briefly provided.

Fabrication and Optimization of Bilayered Nanoporous Anodic Alumina Structures as Multi-Point Interferometric Sensing Platform

Herein, we present an innovative strategy for optimizing hierarchical structures of nanoporous anodic alumina (NAA) to advance their optical sensing performance toward multi-analyte biosensing. This approach is based on the fabrication of multilayered NAA and the formation of differential effective medium of their structure by controlling three fabrication parameters (i.e., anodization steps, anodization time, and pore widening time). The rationale of the proposed concept is that interferometric bilayered NAA (BL-NAA), which features two layers of different pore diameters, can provide distinct reflectometric interference spectroscopy (RIfS) signatures for each layer within the NAA structure and can therefore potentially be used for multi-point biosensing. This paper presents the structural fabrication of layered NAA structures, and the optimization and evaluation of their RIfS optical sensing performance through changes in the effective optical thickness (EOT) using quercetin as a model molecule. The bilayered or funnel-like NAA structures were designed with the aim of characterizing the sensitivity of both layers of quercetin molecules using RIfS and exploring the potential of these photonic structures, featuring different pore diameters, for simultaneous size-exclusion and multi-analyte optical biosensing. The sensing performance of the prepared NAA platforms was examined by real-time screening of binding reactions between human serum albumin (HSA)-modified NAA (i.e., sensing element) and quercetin (i.e., analyte). BL-NAAs display a complex optical interference spectrum, which can be resolved by fast Fourier transform (FFT) to monitor the EOT changes, where three distinctive peaks were revealed corresponding to the top, bottom, and total layer within the BL-NAA structures. The spectral shifts of these three characteristic peaks were used as sensing signals to monitor the binding events in each NAA pore in real-time upon exposure to different concentrations of quercetin. The multi-point sensing performance of BL-NAAs was determined for each pore layer, with an average sensitivity and low limit of detection of 600 nm (mg mL⁻¹)⁻¹ and 0.14 mg mL⁻¹, respectively. BL-NAAs photonic structures have the capability to be used as platforms for multi-point RIfS sensing of biomolecules that can be further extended for simultaneous size-exclusion separation and multi-analyte sensing using these bilayered nanostructures.

Optimization of low-fat meat hamburger formulation containing quince seed gum using response surface methodology

In the present study, feasibility of low-fat hamburger production by partial replacement with quince seed gum (QSG) was investigated. The effects of different QSG levels (1.2, 2.4, 3.6, and 4.8 wt%) on cooking loss, water holding capacity, lipid oxidation, antioxidant activity, and hardness of hamburger were investigated during a period of 9 days. The optimization was carried out based on minimum cooking loss, lipid oxidation, and maximum water holding capacity, antioxidant activity, and tissue hardness. Optimum conditions were achieved as 3.26% oil, 4.73% QSG, and 8.25th day of storagability. According to the optimum conditions, values for cooking loss, water holding capacity, lipid oxidation, free radical scavenging, raw hamburger hardness, and fried hamburger hardness were as 13.80%, 55.61%, 0.59 mg MDA/Kg, 48.12%, 2.99 N, and 8.66 N, respectively. Overall acceptability of optimized hamburgers was better and more acceptable than control ones.

Effects of concentrated and dephytinized wheat bran and rice bran addition on bread properties

Wheat bran and rice bran were concentrated in terms of dietary fiber and were dephytinized by two different methods (fermentation and hydrothermal). Untreated, concentrated, concentrated-dephytinized by fermentation method, and concentrated-dephytinized by hydrothermal method bran samples were each incorporated into flour at levels of 0, 10, 15, and 20%, and their effects on bread properties were investigated. Unprocessed wheat bran and rice bran addition decreased the volume yield, and the specific volume of the bread depends on the incorporation level. A further decrease was observed with the addition of concentrated bran. However, the dephytinization treatments slightly improved these values. The same pattern was observed for the total number of cells and the total cell area of bread crumbs. Both wheat bran and rice bran were observed to cause a darker crumb color, and the effects of bran samples on crumb color were more pronounced after the dephytinization treatment. The addition of concentrated wheat bran and rice bran significantly increased hardness, as well as decreasing springiness, cohesiveness, and resilience of the bread, depending on the bran levels. Although dephytinization treatments enhanced the textural properties of bread, these results were still inferior to those obtained using bread produced with untreated bran. Regarding the dephytinization treatments, the influence of fermentation treatment on bread properties was slightly beneficial compared to hydrothermal treatment.

PRACTICAL APPLICATIONS

Consumption of dietary fiber offers a range of health benefits. Cereal bran has great potential as a dietary fiber source. However, this bran's high phytic acid content and adverse effects on bread quality limit that potential. It is possible to obtain high dietary fiber and low phytic acid bran samples through bran concentration and dephytinization treatments. The dephytinization treatment is an effective method for degradation of phytic acid. The negative effects of wheat bran and rice bran on bread quality decreased significantly following the dephytinization treatments. This study demonstrated that fiber-enriched bread with low phytic acid content and acceptable texture can be produced using concentrated and dephytinized bran.

Utilization of Food Processing By-products as Dietary, Functional, and Novel Fiber: A Review

Fast growing food processing industry in most countries across the world, generates huge quantity of by-products, including pomace, hull, husk, pods, peel, shells, seeds, stems, stalks, bran, washings, pulp refuse, press cakes, etc., which have less use and create considerable environmental pollution. With growing interest in health promoting functional foods, the demand of natural bioactives has increased and exploration for new sources is on the way. Many of the food processing industrial by-products are rich sources of dietary, functional, and novel fibers. These by-products can be directly (or after certain modifications for isolation or purification of fiber) used for the manufacture of various foods, i.e. bread, buns, cake, pasta, noodles, biscuit, ice creams, yogurts, cheese, beverages, milk shakes, instant breakfasts, ice tea, juices, sports drinks, wine, powdered drink, fermented milk products, meat products and meat analogues, synthetic meat, etc. A comprehensive literature survey has been carried on this topic to give an overview in the field dietary fiber from food by-products. In this article, the developments in the definition of fiber, fiber classification, potential sources of dietary fibers in food processing by-products, their uses, functional properties, caloric content, energy values and the labelling regulations have been discussed.

Classification of 31 Korean Wheat (Triticum aestivum L.) Cultivars Based on the Chemical Compositions

Whole grain wheat flour (WGWF) is the entire grain (bran, endosperm, and germ) milled to make flour. The WGWF of 31 Korean wheat (Triticum aestivum L.) cultivars were analyzed for the chemical compositions, and classified into groups by hierarchical cluster analysis (HCL). The average composition values showed a substantial variation among wheat varieties due to different wheat varieties. Wheat cv. Shinmichal1 (waxy wheat) had the highest ash, lipid, and total dietary fiber contents of 1.76, 3.14, and 15.49 g/100 g, respectively. Using HCL efficiently classified wheat cultivars into 7 clusters. Namhae, Sukang, Gobun, and Joeun contained higher protein values (12.88%) and dietary fiber (13.74 %). Regarding multi-trait crop breeding, the variation in chemical compositions found between the clusters might be attributed to wheat genotypes, which was an important factor in accumulating those chemicals in wheat grains. Thus, once wheat cultivars with agronomic characteristics were identified, those properties might be included in the breeding process to develop a new variety of wheat with the trait.

Instant polysaccharide-based emulsions: impact of microstructure on lipolysis

The microstructure of instant emulsions is modulated upon mild shearing through specific rheological manipulation of the continuous phase. Finer emulsions display faster lipolysis kinetics underin vitroconditions.

Effect of substituent pattern and molecular weight of cellulose ethers on interactions with different bile salts

Some known mechanisms proposed for the reduction of blood cholesterol by dietary fibre are: binding with bile salts in the duodenum and prevention of lipid absorption, which can be partially related with the bile salt binding. In order to gain new insights into the mechanisms of the binding of dietary fibre to bile salts, the goal of this work is to study the main interactions between cellulose derivatives and two types of bile salts. Commercial cellulose ethers: methyl (MC), hydroxypropyl (HPC) and hydroxypropylmethyl cellulose (HPMC), have been chosen as dietary fibre due to their highly functional properties important in manufactured food products. Two types of bile salts: sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), have been chosen to understand the effect of the bile salt type. Interactions in the bulk have been investigated by means of differential scanning calorimetry (DSC) and linear mechanical spectroscopy. Results show that both bile salts have inhibitory effects on the thermal structuring of cellulose ethers and this depends on the number and type of substitution in the derivatised celluloses, and is not dependent upon molecular weight. Concerning the bile salt type, the more hydrophobic bile salt (NaTDC) has greater effect on these interactions, suggesting more efficient adsorption onto cellulose ethers. These findings may have implications in the digestion of cellulose-stabilised food matrices, providing a springboard to develop new healthy cellulose-based food products with improved functional properties.

Guava (Psidium guajava L.) Powder as an Antioxidant Dietary Fibre in Sheep Meat Nuggets

This study was conducted to explore the antioxidant potential and functional value of guava (Psidium guajava L.) powder in muscle foods. Guava powder was used as a source of antioxidant dietary fibre in sheep meat nuggets at two different levels i.e., 0.5% (Treatment I) and 1.0% (Treatment II) and its effect was evaluated against control. Guava powder is rich in dietary fibre (43.21%), phenolics (44.04 mg GAE/g) and possesses good radical scavenging activity as well as reducing power. Incorporation of guava powder resulted in significant decrease (p<0.05) in pH of emulsion and nuggets, emulsion stability, cooking yield and moisture content of nuggets while ash and moisture content of emulsion were increased. Total phenolics, total dietary fibre (TDF) and ash content significantly increased (p<0.05) in nuggets with added guava powder. Product redness value was significantly improved (p<0.05) due to guava powder. Textural properties did not differ significantly except, springiness and shear force values. Guava powder was found to retard lipid peroxidation of cooked sheep meat nuggets as measured by TBARS number during refrigerated storage. Guava powder did not affect sensory characteristics of the products and can be used as source of antioxidant dietary fibre in meat foods.

Interactions between cellulose ethers and a bile salt in the control of lipid digestion of lipid-based systems

In order to gain new insights into the potential of specific dietary fibres to control lipid digestion, the goal of this work is to study the main interactions between commercial cellulose ethers, as dietary fibre, and a bile salt, as an important duodenal component present during the digestibility of lipids. These interactions have been evaluated in two different scenarios found for an oil-in-water emulsion on its transit through the duodenum. Namely, interactions in the continuous phase and competitive adsorption at the oil-water interface have been looked at by means of micro-differential scanning calorimetry (micro-DSC) and interfacial tension (IT). Micro-DSC revealed that the presence of the bile salt affects the thermogelation process of cellulose derivatives, suggesting binding to cellulose ethers. The effect on thermogelation seems to be cellulose type-dependent. IT measurements proved the ability of cellulose ethers to compete for the oil-water interface in the presence of the bile salt. Interactions in the bulk might have an impact on this interfacial scenario. These findings may have implications in the digestion of emulsified lipids, hence providing a springboard to develop new cellulose-based food products with improved functional properties.

The effects of biopolymer encapsulation on total lipids and cholesterol in egg yolk during in vitro human digestion

The purpose of this study was to examine the effect of biopolymer encapsulation on the digestion of total lipids and cholesterol in egg yolk using an in vitro human digestion model. Egg yolks were encapsulated with 1% cellulose, pectin, or chitosan. The samples were then passed through an in vitro human digestion model that simulated the composition of mouth saliva, stomach acid, and the intestinal juice of the small intestine by using a dialysis tubing system. The change in digestion of total lipids was monitored by confocal fluorescence microscopy. The digestion rate of total lipids and cholesterol in all egg yolk samples dramatically increased after in vitro human digestion. The digestion rate of total lipids and cholesterol in egg yolks encapsulated with chitosan or pectin was reduced compared to the digestion rate of total lipids and cholesterol in other egg yolk samples. Egg yolks encapsulated with pectin or chitosan had lower free fatty acid content, and lipid oxidation values than samples without biopolymer encapsulation. Moreover, the lipase activity decreased, after in vitro digestion, in egg yolks encapsulated with biopolymers. These results improve our understanding of the effects of digestion on total lipids and cholesterol in egg yolk within the gastrointestinal tract.

Properties of bread dough with added fiber polysaccharides and phenolic antioxidants: a review

During breadmaking, different ingredients are used to ensure the development of a continuous protein network that is essential for bread quality. Interests in incorporating bioactive ingredients such as dietary fiber (DF) and phenolic antioxidants into popular foods such as bread have grown rapidly, due to the increased consumer health awareness. The added bioactive ingredients may or may not promote the protein cross-links. Appropriate cross-links among wheat proteins, fiber polysaccharides, and phenolic antioxidants could be the most critical factor for bread dough enhanced with DF and phenolic antioxidants. Such cross-links may influence the structure and properties of a bread system during baking. This article presents a brief overview of our current knowledge of the fate of the key components (wheat proteins, fibers, and phenolic antioxidants) and how they might interact during bread dough development and baking.

Effects of high- and low-fiber diets on fecal fermentation and fecal microbial populations of captive chimpanzees

We examined fiber fermentation capacity of captive chimpanzee fecal microflora from animals (n = 2) eating low-fiber diets (LFDs; 14% neutral detergent fiber (NDF) and 5% of cellulose) and high-fiber diets (HFDs; 26% NDF and 15% of cellulose), using barley grain, meadow hay, wheat straw, and amorphous cellulose as substrates for in vitro gas production of feces. We also examined the effects of LFD or HFD on populations of eubacteria and archaea in chimpanzee feces. Fecal inoculum fermentation from the LFD animals resulted in a higher in vitro dry matter digestibility (IVDMD) and gas production than from the HFD animals. However, there was an interaction between different inocula and substrates on IVDMD, gas and methane production, and hydrogen recovery (P <0.001). On the other hand, HFD inoculum increased the production of total short-chain fatty acids (SCFAs), acetate, and propionate with all tested substrates. The effect of the interaction between the inoculum and substrate on total SCFAs was not observed. Changes in fermentation activities were associated with changes in bacterial populations. DGGE of bacterial DNA revealed shift in population of both archaeal and eubacterial communities. However, a much more complex eubacterial population structure represented by many bands was observed compared with the less variable archaeal population in both diets. Some archaeal bands were related to the uncultured archaea from gastrointestinal tracts of homeothermic animals. Genomic DNA in the dominant eubacterial band in the HFD inoculum was confirmed to be closely related to DNA from Eubacterium biforme. Interestingly, the predominant band in the LFD inoculum represented DNA of probably new or yet-to-be-sequenced species belonging to mycoplasms. Collectively, our results indicated that fecal microbial populations of the captive chimpanzees are not capable of extensive fiber fermentation; however, there was a positive effect of fiber content on SCFA production.

Effect of maturity and processing on total, insoluble and soluble dietary fiber contents of Indian green leafy vegetables

Vegetables are very important in the diet and provide minerals, vitamins, antioxidants and fiber. A beneficial role of dietary fiber in human nutrition is known but the data on the effect of maturity and processing of Indian vegetables on dietary fiber and its fractions are not available. Hence, the present study was undertaken to generate data on total (TDF), insoluble (IDF) and soluble (SDF) dietary fiber contents of green leafy vegetables (GLV) and to assess the effect of leaf maturity and cooking on these parameters. Sixteen GLV (namely, agathi, alternanthera, amaranth, basella, cabbage, colocasia, coriander, curry leaves, drumstick, fenugreek, hibiscus, mint, portulaca, rumex, spinach and tender tamarind leaves) were analysed for TDF, IDF and SDF by the enzymatic and gravimetric method of the Association of Official Analytical Chemists. Among the GLV analysed, the TDF and IDF contents were the lowest (2.5 g% and 1.6 g%) in basella and were the highest (16.3 g% and 13.4 g%) in curry leaves. The SDF content ranged from 0.7 g% in spinach to 2.9 g% in curry leaves. The SDF as a percentage of the TDF ranged from 11.3% in tender tamarind leaves to 36.0% in basella, but the majority of GLV had around 25% of the TDF as SDF. Significant (P < 0.01) variation was observed between inter-species and intra-species in TDF, IDF and SDF contents of all the GLV. As the leaf matured from tender to mature and to coarse stage, the TDF and IDF contents of amaranth, basella, hibiscus, rumex and spinach increased significantly (P < 0.05), The SDF content significantly (P < 0.05) increased from tender to mature stage in all five GLV, but there was no further increase from mature to coarse stage except in rumex, where a significant (P < 0.01) increase (25%) was observed. Processing/cooking of GLV had no significant effect on their TDF, IDF and SDF contents.

Detection of flavonoids and assay for their antioxidant activity based on enlargement of gold nanoparticles

We report our findings that natural flavonoids such as quercetin, daizeol and puerarin can act as reductants for the enlargement of gold nanoparticles (Au-NPs). Consequently, the UV-vis spectra of a solution containing Au-NPs will be gradually changed, and the molecules of the natural herbs can be detected by making use of changes in the UV-visible spectra. Furthermore, we have prepared a self-assembled monolayer modified electrode by modifying cysteamine on a gold substrate electrode, which is further modified by some Au-NP seeds. When the modified electrode is immersed in a solution containing flavonoids and tetrachloroauric acid as a gold source for the growth of the Au-NP seeds, with the increase of the concentration of flavonoids, the Au-NP seeds on the surface of the modified electrode can be enlarged to varying degrees. As a result, the peak currents in the corresponding cyclic voltammograms are inversely decreased, and simultaneously the peak separation is increased. Therefore, an electrochemical method to detect flavonoids is also proposed. Compared with the optical detection method, the electrochemical method has an extraordinarily lower detection limit and a significantly extended detection range. Moreover, the optical and electrochemical experimental results can be also used to assay and compare the relative antioxidant activities of the flavonoids. Figure Enlargement of Au nanoparticles by flavonoids at cysteamine modified electrode.

Composition, digestibility and application in breadmaking of banana flour

Banana flour (BF) was obtained from unripe banana (Musa paradisiacal L.) and characterized in its chemical composition. Experimental bread was formulated with BF flour and the product was studied regarding chemical composition, available starch (AS), resistant starch (RS) and rate of starch digestion in vitro. The chemical composition of BF showed that total starch (73.36%) and dietary fiber (14.52%) were the highest constituents. Of the total starch, available starch was 56.29% and resistant starch 17.50%. BF bread had higher protein and total starch content than control bread, but the first had higher lipid amount. Appreciable differences were found in available, resistant starch and indigestible fraction between the bread studied, since BF bread showed higher resistant starch and indigestible fraction content. HI-based predicted glycemic index for the BF bread was 65.08%, which was significantly lower than control bread (81.88%), suggesting a "slow carbohydrate" feature for the BF-based goods. Results revealed BF as a potential ingredient for bakery products containing slowly digestible carbohydrates.

Nutritional genomics: the next frontier in the postgenomic era

The interface between the nutritional environment and cellular/genetic processes is being referred to as “nutrigenomics.” Nutrigenomics seeks to provide a molecular genetic understanding for how common dietary chemicals (i.e., nutrition) affect health by altering the expression and/or structure of an individual’s genetic makeup. The fundamental concepts of the field are that the progression from a healthy phenotype to a chronic disease phenotype must occur by changes in gene expression or by differences in activities of proteins and enzymes and that dietary chemicals directly or indirectly regulate the expression of genomic information. We present a conceptual basis and specific examples for this new branch of genomic research that focuses on the tenets of nutritional genomics: 1) common dietary chemicals act on the human genome, either directly or indirectly, to alter gene expression or structure; 2) under certain circumstances and in some individuals, diet can be a serious risk factor for a number of diseases; 3) some diet-regulated genes (and their normal, common variants) are likely to play a role in the onset, incidence, progression, and/or severity of chronic diseases; 4) the degree to which diet influences the balance between healthy and disease states may depend on an individual’s genetic makeup; and 5) dietary intervention based on knowledge of nutritional requirement, nutritional status, and genotype (i.e., “individualized nutrition”) can be used to prevent, mitigate, or cure chronic disease.

Butyrate impairs lipid transport by inhibiting microsomal triglyceride transfer protein in Caco-2 cells

Recently, the idea was advanced that short-chain fatty acids (SCFA) may potentially regulate intestinal fat absorption. The aim of this investigation was to examine the effects of butyrate on the intracellular events governing the assembly of triglyceride-lipoproteins in enterocytes. To this end, differentiated human Caco-2 cells were exposed to 10 or 20 mmol/L butyrate for 20 h. The incubation of Caco-2 cells with butyrate decreased cholesteryl ester (P < 0.005) export in the basolateral medium, probably due to reduced activity of DL-3-hydroxy-3-methyl-glutaryl-CoA reductase (P < 0.02), the rate-limiting enzyme in cholesterol synthesis. Furthermore, a drop was noted in the protein expression of microsomal triglyceride transfer protein (P < 0.03), concomitant with the inhibition of de novo apolipoprotein B-48 synthesis (P < 0.02) and triglyceride-rich lipoprotein output (P < 0.03). Our results support the hypothesis that SCFA can influence lipoprotein concentrations by limiting lipid release from the small intestine into the circulation.

Whole wheat and triticale flours with differing viscosities stimulate cecal fermentations and lower plasma and hepatic lipids in rats

Whole flours from oat, rye or barley effectively modify digestive fermentation and lipid metabolism, whereas the effectiveness of whole wheat flour has not been established. To address this question, cecal digestion, short-chain fatty acid (SCFA) metabolism and cholesterol metabolism were investigated in four groups of rats fed the following semipurified diets differing in their carbohydrate source: a control diet (purified wheat starch) and three whole cereal flour diets [Valoris wheat (Wv), Soissons wheat (Ws), or Carnac triticale (Tc)]. Wv is particularly viscous and rich in arabinoxylans, and Tc is richer in hemicellulose than wheat. Compared with controls, rats fed the whole-flour diets had enlarged ceca and a moderate acidification of the bulk pH ( approximately 6.4). In these rats, the cecal SCFA pool size was enhanced (P < 0.05), and the SCFA molar ratio reflected propionic/butyric acid-rich fermentations, especially in those fed TC: The portal SCFA concentrations reflected the rise of the acetic and propionic acid pools in the cecum, whereas portal butyric acid remained relatively low, probably reflecting extensive metabolism by the cecal wall. The fecal excretion of total steroids (bile acids + sterols) was markedly enhanced by all of the whole-flour diets, with Wv (+78%) > Tc (+64%) > Ws (+47%). In parallel, there was a significant plasma cholesterol-lowering effect for rats fed Wv (-27%) and Tc (-32%) and a plasma triglyceride-lowering effect (approximately -40%) in all rats fed whole-flour diets (P < 0.05). This effect was observed mainly for triglyceride-rich lipoprotein-cholesterol, whereas HDL cholesterol was unaffected. These results indicate that whole wheat flours can strikingly affect cecal SCFA, especially butyrate, and are effective plasma cholesterol-lowering agents.

Tolerance of low-digestible carbohydrates: a general view

The tolerance of low-digestible carbohydrates (LDCs) may be measured as the potential to cause abdominal symptoms and laxation. Tolerance of any one LDC is determined by its concentration in the food product eaten, the amount of the food product eaten, the frequency of eating the food and the consumption of other foods (increasing tolerance) and water decreasing tolerance). Added to these, individuals vary considerably in their response to low-digestible carbohydrates in the reporting of gastrointestinal symptoms. A precise maximum no-response dose is sometimes difficult to obtain because some dose--response curves are distinctly sigmoidal. Food regulators hoping to set a trigger level at which laxation may occur have been unable to take account of all these factors because the necessary information matrices are not available for any one LDC. Nevertheless analysis of the data shows consistent trends and for circumstances when food is consumed throughout the day it now seems feasible to assign specific tolerances to specific low-digestible carbohydrates, especially the polyols for which most is known. The method by which the no-effect dose or laxative threshold is expressed is critical to its application to individual foods.