Influence of chemical and physical modification on the bile acid binding capacity of dietary fibre from lupins (Lupinus angustifolius L.)

A review of healthy role of dietary fiber in modulating chronic diseases

Dietary fiber (DF) is considered an interventional diet beneficial for human health. High DF intake effectively reduces the incidence of three major chronic diseases, type 2 diabetes (T2DM), cardiovascular disease (CVD), and colorectal cancer (CRC). The health benefits of DF are closely related to their physicochemical properties with major positive roles in human digestion and intestinal health. However, mechanisms linking DF with diseases remain unclear. The development of genomics, metabolomics, and immunology, and the powerful combination of animal models and clinical trials, have facilitated a better understanding of the relationships between DF and diseases. Accumulating evidence suggests that the physical existence of DF and DF-microbiota interaction are the key parameters controlling the action mechanisms of DF in chronic diseases. Therefore, this review discusses the potential mechanism of DF modulating T2DM, CVD, and CRC, therefore providing a theoretical basis for more effective use of DF to intervene in chronic diseases.

Exploring faba beans (Vicia faba L.): bioactive compounds, cardiovascular health, and processing insights

Faba beans (Vicia faba L.), integral to the legume family, are a significant component of the global pulse market because of their nutritional richness and positive health implications. While existing reviews have extensively covered the nutritional composition and anti-nutritional factors of faba beans, and their utilization in food product development, the insights into the optimization of processing methods and upcycling the wastewater during faba bean processing remain insufficient. Therefore, this review focuses on consolidating information about their bioactive compounds, elucidating associated health benefits and unveiling the possible application of processing water derived from faba beans. Key issues discussed include the impact of bioactive compounds in faba beans on cardiovascular health and carcinogenic condition, the challenges in processing that affect bioactive content, and the potential nutritional and functional applications of processing water in food production.

Polysaccharide-based biosorbents for cholesterol and bile salts in gastric-intestinal passage: Advances and future trends

Cholesterol is one of the hazard elements for many cardiovascular diseases, but many cholesterol-lowering drugs are expensive and unhealthy. Therefore, it is necessary to develop edible and safe biosorbents to reduce excess cholesterol and bile salts in the gastric-intestinal passage. Polysaccharide-based biosorbents offer a feasible strategy for decreasing them. This review summarized polysaccharide-based biosorbents that have been developed for adsorbing cholesterol and bile salts from the gastric-intestinal passage and analyzed common modification methods for these adsorbents. Finally, the adsorption models were also elucidated. Polysaccharides, including β-cyclodextrin, pectin, chitin/chitosan, dietary fiber extract, and cellulose, have been proposed for adsorbing cholesterol and bile salts in the gastric-intestinal passage as biosorbents. This is mainly due to the retention of pores, the capture of the viscosity network, and the help of hydrophobic interactions. In spite of this, the adsorption capacity of polysaccharides is still limited. Therefore, the modifications for them became the most popular areas in the recent studies of in vitro cholesterol adsorption. Chemical approaches namely grafting, (1) acetylation, (2) hydroxypropylation, (3) carboxymethylation, and (4) amination are considered to modify the polysaccharides for higher adsorption ability. Moreover, ultrasonic/microwave/pressure treatment and micron technology (microfluidization, micronization, and ball milling) are effective physical modification methods, while the biological approach mainly refers to enzymatic hydrolysis and microbial fermentation. The adsorption models are generally explained by two adsorption isotherms and two adsorption kinetics. In sum, it is reckoned that further food applications will follow soon.

Dietary fiber modification: structure, physicochemical properties, bioactivities, and application-a review

There is increasing attention on the modification of dietary fiber (DF), since its effective improvement on properties and functions of DF. Modification of DF can change their structure and functions to enhance their bioactivities, and endow them with huge application potential in the field of food and nutrition. Here, we classified and explained the different modification methods of DF, especially dietary polysaccharides. Different modification methods exert variable effects on the chemical structure of DF such as molecular weight, monosaccharide composition, functional groups, chain structure, and conformation. Moreover, we have discussed the change in physicochemical properties and biological activities of DF, resulting from alterations in the chemical structure of DF, along with a few applications of modified DF. Finally, we have summarized the modified effects of DF. This review will provide a foundation for further studies on DF modification and promote the future application of DF in food products.

Bile Acid Sequestrants for Hypercholesterolemia Treatment Using Sustainable Biopolymers: Recent Advances and Future Perspectives

Bile acids, the endogenous steroid nucleus containing signaling molecules, are responsible for the regulation of multiple metabolic processes, including lipoprotein and glucose metabolism to maintain homeostasis. Within our body, they are directly produced from their immediate precursors, cholesterol C (low-density lipoprotein C, LDL-C), through the enzymatic catabolic process mediated by 7-α-hydroxylase (CYP7A1). Bile acid sequestrants (BASs) or amphiphilic resins that are nonabsorbable to the human body (being complex high molecular weight polymers/electrolytes) are one of the classes of drugs used to treat hypercholesterolemia (a high plasma cholesterol level) or dyslipidemia (lipid abnormalities in the body); thus, they have been used clinically for more than 50 years with strong safety profiles as demonstrated by the Lipid Research Council-Cardiovascular Primary Prevention Trial (LRC-CPPT). They reduce plasma LDL-C and can slightly increase high-density lipoprotein C (HDL-C) levels, whereas many of the recent clinical studies have demonstrated that they can reduce glucose levels in patients with type 2 diabetes mellitus (T2DM). However, due to higher daily dosage requirements, lower efficacy in LDL-C reduction, and concomitant drug malabsorption, research to develop an "ideal" BAS from sustainable or natural sources with better LDL-C lowering efficacy and glucose regulations and lower side effects is being pursued. This Review discusses some recent developments and their corresponding efficacies as bile removal or LDL-C reduction of natural biopolymer (polysaccharide)-based compounds.

Production, physicochemical characteristics, and in vitro biological activities of polysaccharides obtained from fresh bitter gourd (Momordica charantia L.) via room temperature extraction techniques

In this study, polysaccharides (BPSs) were obtained from fresh bitter gourd (Momordica charantia L.) by room temperature extraction techniques, including three-phase partitioning (TPP) and ultrasonic-assisted extraction (UAE) performed in different solvents. The results showed that the extraction methods had significant influence on the extraction yield, chemical composition, weight-average molecular weight (M_w), monosaccharide composition, preliminary structural characterization and microstructure of the BPSs. The BPS-W sample obtained from the bitter gourd residue via UAE in distilled water had a higher uronic acid content (24.22%) and possessed stronger antioxidant capacities and α-amylase and α-glycosidase inhibitory activities than BPS-C extracted with UAE in citric acid, BPS-A extracted with UAE in 1.25 mol/L NaOH/0.05% NaBH₄, and BPS-J extracted from bitter gourd juice by TPP. Moreover, BPS-A, which had the lowest M_ws, showed the best bile acid-binding capacity among the four BPSs. This study had great potentials for the preparation of bioactive polysaccharides from fresh vegetables.

Soluble dietary fibers from black soybean hulls: Physical and enzymatic modification, structure, physical properties, and cholesterol binding capacity

We used ultrasound-microwave comodification and enzyme modification (cellulase and hemicellulase) methods to extract soluble dietary fibers (SDFs) from black soybean hulls. Moreover, the structure, physical, and chemical properties, as well as the cholesterol-binding capacity of SDFs before and after modification were analyzed. The average molecular weight of SDFs extracted from raw black soybean hulls was 2.815 × 105  Da. By comparison, the average molecular weight of SDFs from ultrasound-microwave comodified hulls and enzyme-modified hulls decreased by 33.21% and 45.29%, respectively. The water-holding capacity (WHC), water-swelling capacity (WSC), and oil-holding capacity (OHC) of the extracted SDFs modified by the ultrasound-microwave method were 3.79 g/g, 1.39 mL/g, and 1.14 g/g, respectively, a 9.54%, 23.01%, and 17.53% increase from the values of raw SDF. The WHC, WSC, and OHC of SDFs modified via the enzyme method were 3.59 g/g, 1.25 mL/g, and 1.03 g/g, respectively, with a 3.76%, 10.62%, and 6.19% increase when compared to raw SDFs. The cholesterol-binding capacity of SDFs modified via the ultrasound-microwave and enzyme methods was 13.82 and 12.34 mg/g, respectively, with an increase of 47.98% and 32.20% when compared to raw SDFs. The changes in structure and physical and chemical properties were shown to be closely related to the significantly improved cholesterol-binding capacity of the SDFs from modified black soybean hulls. This provides a theoretical basis for subsequent research and development of black soybean hulls products. PRACTICAL APPLICATION: At present, the black soybean hull, a byproduct of general grains, is usually abandoned, but black soybean hull is rich in dietary fiber. Enzymatic modification and ultrasound-microwave comodification were used to treat black soybean hull to prepare small molecular weight, highly active soluble dietary fiber. This research is of great significance to the deep processing of black soybean hull and improvement of the economic benefits of black soybean byproducts.

Characterisation of the molecular interactions between primary bile acids and fractionated lupin cotyledons (Lupinus angustifolius L.)

Interactions between bile acids and plant-based materials, and the related feedback mechanisms in enterohepatic circulation, have been considered targets for lowering cholesterol. This study aimed to identify lupin compounds that interact with primary bile acids on molecular level. Lupin cotyledons were fractionated and bile acid adsorbing activities were investigated using in vitro digestion, equilibrium dialysis and kinetic analyses. Protein- and fibre-enriched fractions significantly (p ≤ 0.05) adsorbed chenodesoxycholic acids (up to 2.33 µmol/100 g DM). Alcohol purification showed that bile acid adsorption is independent of protein and fibre structures. Moreover, high adsorption was observed with an alcohol extract (6.97 µmol chenodesoxycholic acids/100 g DM) that was rich in phytochemicals, such as flavonoids (1842 mg/100 g DM). These results suggest the formation of hydrophobic interactions between polyphenols and bile acids. Further studies of molecular mechanisms are required to define the contributions of polyphenols to the cholesterol-lowering actions of lupins.

Manipulation of the dry bean (Phaseolus vulgaris L.) matrix by hydrothermal and high-pressure treatments: Impact on in vitro bile salt-binding ability

The capacity of high-fiber foods to sequester BS during digestion is considered a mechanism to lower serum-cholesterol. We investigated the effect of hydrothermal (HT) and high-hydrostatic-pressure (HHP) on the bile salt (BS)-binding ability of dry beans, and how this relates to changes in bean microstructure, fiber content (insoluble-IDF/soluble-SDF), and viscosity. HT and HHP-600 MPa led to significant IDF reduction, including resistant starch (RS), whereas 150-450 MPa significantly increased RS, without modifying IDF/SDF content. Microscopy analysis showed that heating disrupted the bean cell wall integrity, protein matrix and starch granules more severely than 600 MPa; however, tightly-packed complexes of globular starch granules-protein-cell wall fiber formed at HHP ≤ 450 MPa. While HT significantly reduced BS-binding efficiency despite no viscosity change, HHP-treatments maintained or enhanced BS-retention. 600 MPa-treatment induced the maximum BS-binding ability and viscosity. These results demonstrate that BS-binding by beans is not solely based on their fiber content or viscosity, but is influenced by additional microstructural factors.

Retention of Primary Bile Acids by Lupin Cell Wall Polysaccharides Under In Vitro Digestion Conditions

Interference of dietary fibres with the enterohepatic circulation of bile acids is proposed as a mechanism for lowering cholesterol. We investigated how lupin hull and cotyledon dietary fibres interact with primary bile acids using an in vitro model under simulated upper gastrointestinal conditions. Cell wall polysaccharides were isolated and extracted to separate pectin-like, hemicellulosic, and lignocellulosic structures. Lupin hull consisted mainly of structural components rich in cellulose. The viscosity of the in vitro digesta of lupin hull was low, showing predominantly liquid-like viscoelastic properties. On the other hand, lupin cotyledon fibre retarded bile acid release due to increased viscosity of the in vitro digesta, which was linked with high contents of pectic polymers forming an entangled network. Molecular interactions with bile acids were not measured for the hull but for the cotyledon, as follows: A total of 1.29 µmol/100 mg DM of chenodesoxycholic acids were adsorbed. Molecular interactions of cholic and chenodesoxycholic acids were evident for lignin reference material but did not account for the adsorption of the lupin cotyledon. Furthermore, none of the isolated and fractionated cell wall materials showed a significant adsorptive capacity, thus disproving a major role of lupin cell wall polysaccharides in bile acid adsorption.

Valorizing cabbage (Brassica oleracea L. var. capitata) and capsicum (Capsicum annuum L.) wastes: in vitro health-promoting activities

The capsicum seed core and cabbage outer leaves are common wastes generated in the vegetable processing industry. We explored the in vitro health-promoting activity of these waste products for valorization. Freeze-dried and pulverized cabbage wastes had a high bile acid binding capacity and the capsicum wastes inhibited glucose dialysis more effectively. Methanolic extracts prepared with conventional solvent extraction and ultrasound-assisted extraction were analyzed to determine their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, in vitro α-amylase inhibitory, in vitro lipase inhibitory, and prebiotic activity. Crude extracts of cabbage and capsicum wastes were screened using GC-MS analysis. The cabbage waste extracts showed high antioxidant activities but did not inhibit α-amylase. The capsicum waste extracts inhibited both lipase and α-amylase activities and supported the growth of the probiotic bacterium, Lactobacilli brevis. Volatile compounds of the vegetables consisted mainly of phenols and fatty acid esters. In all assays except the α-amylase inhibition assay, the extracts prepared with ultrasound-assisted solvent extraction showed higher activity than those prepared using the conventional method. The capsicum seed core and cabbage outer leaves are potential sources of phytochemicals and antioxidant fibers. Capsicum waste extract supported probiotic bacterial growth without a lag phase. These waste products may be processed into high-value functional ingredients.

In Vitro Interactions of Dietary Fibre Enriched Food Ingredients with Primary and Secondary Bile Acids

Dietary fibres are reported to interact with bile acids, preventing their reabsorption and promoting their excretion into the colon. We used a method based on in vitro digestion, dialysis, and kinetic analysis to investigate how dietary fibre enriched food ingredients affect the release of primary and secondary bile acids as related to viscosity and adsorption. As the main bile acids abundant in humans interactions with glyco- and tauroconjugated cholic acid, chenodesoxycholic acid and desoxycholic acid were analysed. Viscous interactions were detected for apple, barley, citrus, lupin, pea, and potato derived ingredients, which slowed the bile acid release rate by up to 80%. Adsorptive interactions of up to 4.7 μmol/100 mg DM were significant in barley, oat, lupin, and maize preparations. As adsorption directly correlated to the hydrophobicity of the bile acids the hypothesis of a hydrophobic linkage between bile acids and dietary fibre is supported. Delayed diffusion in viscous fibre matrices was further associated with the micellar properties of the bile acids. As our results indicate changes in the bile acid pool size and composition due to interactions with dietary fibre rich ingredients, the presented method and results could add to recent fields of bile acid research.

Differentiation of Adsorptive and Viscous Effects of Dietary Fibres on Bile Acid Release by Means of In Vitro Digestion and Dialysis

To explain the cholesterol-reducing effects of dietary fibres, one of the major mechanisms proposed is the reduced reabsorption of bile acids in the ileum. The interaction of dietary fibres with bile acids is associated with their viscous or adsorptive effects. Since these fibre characteristics are difficult to investigate in vivo, suitable in vitro methodologies can contribute to understanding the mechanistic principles. We compared the commonly used centrifugal approach with a modified dialysis method using dietary fibre-rich materials from different sources (i.e., barley, citrus, lupin, and potato). Digestion was simulated in vitro with oral, gastric, and small intestinal digestion environments. The chyme was dialysed and released bile acids were analysed by high-performance liquid chromatography. The centrifugation method showed adsorptive effects only for cholestyramine (reference material) and a high-fibre barley product (1.4 µmol taurocholic acid/100 mg dry matter). Alternatively, the dialysis approach showed higher values of bile acid adsorption (2.3 µmol taurocholic acid/100 mg dry matter) for the high-fibre barley product. This indicated an underestimated adsorption when using the centrifugation method. The results also confirmed that the dialysis method can be used to understand the influence of viscosity on bile acid release. This may be due to entrapment of bile acids in the viscous chyme matrix. Further studies on fibre structure and mechanisms responsible for viscous effects are required to understand the formation of entangled networks responsible for the entrapment of the bile acids.

Comparison Study on Polysaccharide Fractions from Laminaria japonica: Structural Characterization and Bile Acid Binding Capacity

Our previous study has suggested that the crude polysaccharide obtained from Laminaria japonica by acid assisted extraction (LP-A) have significant bile acid-binding capacity, which probably ascribed to its specific structure characterization. The relationship between structure characterization and bile acid-binding capacity of the purified LP-A fractions are still unknown. This paper conducted a comparison study on the structure characterization and bile acid-binding capacity of three LP-A fractions (LP-A4, LP-A6, and LP-A8). The results indicated that LP-A4, LP-A6, and LP-A8, characterized as mannoglucan, fucomannoglucan, and fucogalactan, had significantly different structure characterization. Furthermore, the bile acid-binding capacity of LP-A8 was obviously higher than the other fractions, which may be attributed to its highly branched structure, abundant sulfate, fucose, and galactose in chemical composition and denser interconnected macromolecule network in molecular morphology. This study provides scientific evidence for the potential utilization of LP-A8 as an attractive functional food supplement candidate for the hyperlipidemia population.

A comparison study on polysaccharides extracted from Laminaria japonica using different methods: structural characterization and bile acid-binding capacity

In this study, the structural characterization and bile acid-binding capacity of Laminaria japonica polysaccharides (LP), obtained by seven different extraction methods, were investigated. The results indicated that extraction methods exhibited significant effects on extraction yield, molecular weight, monosaccharide composition and the content of neutral sugar, fucose, uronic acid and sulfate of LP. AFM analysis indicated that LP extracted by different methods exhibited certain different, flexible and worm-like chains with many branches. Rheological measurements showed that the LP, obtained by pressurized hot water extraction and acid assisted extraction, exhibited lower viscosity due to their lower molecular weight, compared to other extracted polysaccharides. The bile acid-binding capacity of acid assisted extracted LP was significantly higher than other LP samples tested, which was probably ascribed to its highly branched structure, low molecular weight, low viscosity and abundant uronic acid and fucose in total monosaccharides. The present study provides scientific evidence and advances in the preparation technology and a method for evaluating hypolipidemic activities of L. japonica polysaccharides.

Bioactivities of alternative protein sources and their potential health benefits

Increasing the utilisation of plant proteins is needed to support the production of protein-rich foods that could replace animal proteins in the human diet so as to reduce the strain that intensive animal husbandry poses to the environment.

Effect of Wheat Dietary Fiber Particle Size during Digestion In Vitro on Bile Acid, Faecal Bacteria and Short-Chain Fatty Acid Content

The influence of bile acid concentration on the growth of Bifidobacterium spp. and Lactobacillus spp. bacteria was demonstrated. Exposing these bacteria to the environment containing bile acid salts, and very poor in nutrients, leads to the disappearance of these microorganisms due to the toxic effect of bile acids. A multidimensional analysis of data in the form of principal component analysis indicated that lactic acid bacteria bind bile acids and show antagonistic effect on E. coli spp. bacteria. The growth in E. coli spp. population was accompanied by a decline in the population of Bifidobacterium spp. and Lactobacillus spp. with a simultaneous reduction in the concentration of bile acids. This is direct proof of acid binding ability of the tested lactic acid bacteria with respect to cholic acid, lithocholic acid and deoxycholic acid. This research demonstrated that the degree of fineness of wheat dietary fibre does not affect the sorption of bile acids and growth of some bacteria species; however, it has an impact on the profile of synthesized short-chained fatty acids. During the digestion of a very fine wheat fibre fraction (WF 90), an increase in the concentration of propionic and butyric acids, as compared with the wheat fiber fraction of larger particles - WF 500, was observed. Our study suggested that wheat fibre did not affect faecal bacteria growth, however, we observed binding of bile acids by Bifidobacterium spp. and Lactobacillus spp.

Binding of bile acids by pastry products containing bioactive substances during in vitro digestion

The modern day consumer tends to choose products with health enhancing properties, enriched in bioactive substances. One such bioactive food component is dietary fibre, which shows a number of physiological properties including the binding of bile acids. Dietary fibre should be contained in everyday, easily accessible food products. Therefore, the aim of this study was to determine sorption capacities of primary bile acid (cholic acid - CA) and secondary bile acids (deoxycholic - DCA and lithocholic acids - LCA) by muffins (BM) and cookies (BC) with bioactive substances and control muffins (CM) and cookies (CC) in two sections of the in vitro gastrointestinal tract. Variations in gut flora were also analysed in the process of in vitro digestion of pastry products in a bioreactor. Enzymes: pepsin, pancreatin and bile salts: cholic acid, deoxycholic acid and lithocholic acid were added to the culture. Faecal bacteria, isolated from human large intestine, were added in the section of large intestine. The influence of dietary fibre content in cookies and concentration of bile acids in two stages of digestion were analysed. Generally, pastry goods with bioactive substances were characterized by a higher content of total fibre compared with the control samples. These products also differ in the profile of dietary fibre fractions. Principal Component Analysis (PCA) showed that the bile acid profile after two stages of digestion depends on the quality and quantity of fibre. The bile acid profile after digestion of BM and BC forms one cluster, and with the CM and CC forms a separate cluster. High concentration of H (hemicellulose) is positively correlated with LCA (low binding effect) and negatively correlated with CA and DCA contents. The relative content of bile acids in the second stage of digestion was in some cases above the content in the control sample, particularly LCA. This means that the bacteria introduced in the 2nd stage of digestion synthesize the LCA.

Modification of deoiled cumin dietary fiber with laccase and cellulase under high hydrostatic pressure

In this study, we evaluated the effects of high hydrostatic pressure (HHP) and enzyme (laccase and cellulase) treatment on the structural, physicochemical, and functional properties and antioxidant activity of deoiled cumin dietary fiber (DF). HHP-enzyme treatment increased the contents of soluble dietary fiber (SDF) (30.37 g/100g), monosaccharides (except for glucose), uronic acids, and total polyphenol. HHP-enzyme treatment altered the honey-comb structure of DF and generated new polysaccharides. DF modified by HHP-enzyme treatment exhibited improved water retention capacity (10.02 g/g), water swelling capacity (11.19 mL/g), fat and glucose absorption capacities (10.44 g/g, 22.18-63.54 mmol/g), α-amylase activity inhibition ration (37.95%), and bile acid retardation index (48.85-52.58%). The antioxidant activity of DF was mainly correlated to total polyphenol content (R=0.8742). Therefore, DF modified by HHP-enzyme treatment from deoiled cumin could be used as a fiber-rich ingredient in functional foods.

The formation of short-chain fatty acids is positively associated with the blood lipid-lowering effect of lupin kernel fiber in moderately hypercholesterolemic adults

Lupin kernel fiber beneficially modifies blood lipids because of its bile acid-binding capacity. The aim of this study was to evaluate the preventive effects of a lupin kernel fiber preparation on cardiovascular diseases and to clarify possible mechanisms. In a randomized, double-blind, controlled crossover trial, 60 moderately hypercholesterolemic adults (plasma total cholesterol: >5.2 mmol/L) passed 3 intervention periods in different orders with a 2-wk washout phase between each. Participants consumed either a high-fiber diet containing 25-g/d lupin kernel fiber (LF) or citrus fiber (CF), or a low-fiber control diet (CD) for 4 wk each. Anthropometric, plasma, and fecal variables were assessed at baseline and after the interventions. Contrary to the CF period, total (9%) and LDL (12%) cholesterol as well as triacylglycerols (10%) were lower after the LF period when compared with the CD period [P ≤ 0.02, adjusted for baseline, age, gender, and body mass index (BMI)]. HDL cholesterol remained unchanged. Moreover, the LF period reduced high-sensitivity C-reactive protein (P = 0.02) and systolic blood pressure (P = 0.01) when compared with baseline. Bile acid binding could not be shown because the excretion of total bile acids remained constant after the high-fiber diets. However, the LF period resulted in an enhanced formation of the main short-chain fatty acids in comparison with the CD period. During the CF period, only acetate increased significantly. Both high-fiber diets led to higher satiety and modified nutritional behavior, resulting in significantly lower body weight, BMI, and waist circumference compared with the CD period. The blood lipid-lowering effects of LF are apparently not a result of bile acid binding. Rather, we hypothesize for the first time, to our knowledge, that the blood lipid-lowering effects of LF may be mainly attributed to the formation of short-chain fatty acids, specifically propionate and acetate. This trial was registered at clinicaltrials.gov as NCT01035086.

Effects of legume kernel fibres and citrus fibre on putative risk factors for colorectal cancer: a randomised, double-blind, crossover human intervention trial

Background

In some studies, high intake of dietary fibre has been associated with a lower risk of colorectal cancer. The present study aimed to compare physiological effects of three legume kernel fibres and citrus fibre on blood lipids (primary outcome: LDL cholesterol) and colonic health.

Methods

Ninety-two subjects were recruited for the double-blind, controlled crossover trial. Seventy-eight participants were randomly divided into three groups. Following run-in, half the volunteers from each group consumed 25 g/d of a legume fibre, comprising blue lupin fibre, white lupin fibre, and soya fibre for two weeks. The other half received the same amount of citrus fibre (active comparator). The intervention was crossed within each group after two weeks wash-out. At the end of run-in and intervention, a quantitative faeces collection took place and fasting blood samples were drawn. Repeated measures ANOVA with the general linear model were applied to evaluate changes following interventions.

Results

Seventy-six subjects completed the study. Dietary fibre intake during all interventions was approximately twice the fibre intake at run-in. The lupin fibre supplementations increased daily faecal dry matter and faecal weight compared to run-in, representing an increase of 1.76 g faeces/g additional dietary fibre contributed by blue lupin and of 1.64 g faeces/g by white lupin, respectively. Both lupin interventions led to a significantly enhanced formation of short-chain fatty acids, and blue lupin fibre to a decrease in faecal pH compared to run-in (0.27 units, P < 0.01). Further, blue lupin increased primary bile acids-excretion (P = 0.02). All legume fibres reduced faecal concentrations of total and secondary bile acids (blue lupin: 16%; white lupin: 24%; soya: 16%). Blood lipids were not influenced by any intervention. No serious adverse effects were observed.

Conclusions

The tested fibre preparations do not affect lipid metabolism through bile acid-binding in normocholesterolaemic subjects. However, particularly blue lupin kernel fibre improve colonic function and have beneficial effects on putative risk factors for colorectal cancer such as faecal mass, transit time, SCFA, faecal pH, and secondary bile acid concentration. Therefore, enhancing dietary fibre intake through blue lupin up to about 50 g/d can be recommended.

Trial registration

NCT01036308

Effects of psyllium on metabolic syndrome risk factors

High-fibre intake has been shown to reduce the risk of metabolic syndrome (MS), cardiovascular disease and type 2 diabetes. Psyllium is one of the most widely used fibre supplements because it is reasonably cheap and is better tolerated than other fibre supplements. The review of the literature supports the notion that the consumption of psyllium provides benefits to many components of the MS. Psyllium supplementation does improve glucose levels and insulin response, blood pressure, as well as lipid profile in both animals and humans, thereby reducing metabolic risk factors. Appetite has also been reported to decrease after the consumption of psyllium in most studies. Collectively, psyllium supplementation could be promoted to patients who present MS risk factors, such as hypercholesterolaemia, hypertriglyceridaemia and hyperglycaemia. It may also play a role in controlling body weight, body composition, appetite and hypertension, but further investigation is still required.