Despite decades of research showing that dietary fiber is linked to lower rates of cardiovascular disease, type 2 diabetes, and colorectal cancer, most adults consume less than half of the recommended daily amount. For many patients, the advice to "eat more fiber" is familiar but not well understood in practice. Because fiber significantly influences gut health, glycemic control, lipid metabolism, and satiety, it has important implications for preventing and managing chronic diseases. Historical Definitions of Dietary Fiber Dietary fiber is a complex carbohydrate from the structural parts of plant foods, generally classified as soluble or insoluble. Soluble fiber dissolves in water and is partially fermented in the colon, while insoluble fiber does not dissolve and mainly adds bulk to the stool.[ASPEN Adult Nutrition Support Core Curriculum, Fourth Edition. 2025] No single universally accepted definition of dietary fiber has been established. In 1953, E.H. Hipsley of Australia first described fiber as the "nondigestible constituent that makes up the plant cell wall." Since then, many organizations and countries have proposed different definitions.  Creating a universally accepted definition remains difficult as researchers discover new compounds that share either the chemical structure or the physiological functions of fiber, but not always both. From a health perspective, fiber is best defined by its physiological effects, eg, supporting regular bowel movements, improving glycemic control, and lowering cholesterol. However, for food labeling and analytical purposes, scientists and regulatory agencies rely on the Association of Official Analytical Chemists' definition, based on chemical and analytical properties. Most definitions agree that fiber is composed of carbohydrates and lignin that resist digestion in the small intestine and are partially or fully fermented in the large intestine, producing beneficial metabolites such as short-chain fatty acids. Understanding these definitions is essential for clinicians, as it supports effective patient counseling, accurate interpretation of nutrition labels, and selection of foods that reliably provide the intended health benefits. Nutritional Impact of Dietary Fiber All dietary fiber comes from plant-based foods, including fruits, vegetables, whole grains, legumes, nuts, and seeds. Fiber plays a vital role in digestion, nutrient absorption, and gastrointestinal health. Soluble fibers, eg, pectin, gums, mucilage, fructans, and some resistant starches, absorb water to form a gel that slows gastric emptying, delays glucose absorption, and blunts postmeal blood sugar spikes. Soluble fiber also binds bile acids, modestly lowering LDL cholesterol levels, and acts as a prebiotic substrate for gut microbiota that produce short-chain fatty acids, which decrease inflammation and support metabolic and immune functions. In contrast, insoluble fiber does not dissolve in water. Insoluble fibers include lignin, cellulose, and hemicellulose, which reduce intestinal transit time and increase fecal bulk to promote digestive regularity. Both soluble and insoluble fibers enhance satiety, aid in weight management, and support cardiovascular and metabolic health. Added, or functional, fiber refers to indigestible carbohydrates that are extracted or isolated from plant sources and have been shown to offer health benefits, including better blood glucose regulation, lower cholesterol, and improved bowel regularity. This category includes certain concentrated or synthetically produced nondigestible carbohydrates, eg, psyllium, resistant starch, inulin, polydextrose, and cellulose. The effects of added fibers vary based on their chemical structure and physical properties, and laboratory-synthesized fibers must demonstrate proven health benefits before being labeled as dietary fiber. Adding fibers to foods can help individuals meet daily fiber goals when the naturally occurring fiber from whole foods is insufficient. Consumers can identify added fibers by looking for terms like "soluble fiber," "psyllium," "inulin," "resistant starch," or "functional fiber," which are listed under total dietary fiber on the Nutrition Facts label. Dietary Fiber Recommendations The recommended adequate daily intake for fiber is 25 g for women and 38 g for men, or 14 g per 1,000 kcal consumed. This recommendation is based on evidence showing protection against coronary heart disease and other chronic diseases. It is supported by the Institute of Medicine, the Academy of Nutrition and Dietetics, and major U.S. guidelines. For children and adolescents, the target intake varies by age and sex, from 19 g daily for young children to 31 to 38 g/day for older boys and 25 to 26 g/day for older girls. Between 2017 and 2020, the mean consumption of dietary fiber by American adults was only 17 g per day, about half of the recommended adequate intake level. Approximately 94% of American children and adults fail to meet the adequate intake levels for dietary fiber. Dietary sources include: Soluble fiber: Fruits high in soluble fiber: apples, pears, citrus, berries, plums, peaches, and apricots. Vegetables high in soluble fiber: carrots, broccoli, Brussels sprouts, sweet potatoes, turnips, onions, and asparagus. Legumes, grains, and seeds high in soluble fiber: beans, lentils, chickpeas, oats, barley, rye, and chia seeds. Insoluble fiber : Fruits high in insoluble fiber: apples and pears with skin, berries (especially raspberries and blackberries), grapes, bananas, and oranges. Vegetables high in insoluble fiber: green beans, cauliflower, zucchini, broccoli stems, leafy greens (spinach, kale, and collards), potatoes, celery, and bell peppers. Other sources of insoluble fiber: whole grains (whole wheat, brown rice, rye, corn bran, and bulgur), nuts and seeds (almonds, walnuts, flaxseeds, chia seeds), legumes (beans, lentils, chickpeas, and peas).

Psyllium husk gel (PHG) is a soluble dietary fiber with well-documented health benefits, yet its application in whole wheat products is constrained by complex interactions with the gluten network. This study investigated the effects of PHG at 0%, 2%, 8%, and 14% on the phase mass and protein redistribution, microstructure, thermal properties, and steamed bread quality of whole wheat dough. PHG reduced the aqueous phase mass after ultracentrifugation and reallocated proteins predominantly to the water-insoluble fraction, while non-protein substances shifted to the water-soluble fraction associated with insoluble matter. Scanning electron microscopy revealed that PHG transformed the dough from discrete starch granules into continuous aggregates with enhanced granule coverage, and X-ray micro-computed tomography further quantified that PHG increased mean gas cell wall thickness by 3.2%-43.1%, with uniform thickening achieved only at 8% addition. At 14%, PHG disrupted thickness uniformity and reduced the optimal thermal stability observed at 8%, as evidenced by a 28.6% higher tan δ at 60°C and a 15.8% lower residual weight at 350°C. Nevertheless, both 8% and 14% PHG still maintained favorable crumb cellular structure, characterized by higher junction numbers and increased cell wall thickness relative to the control, which resulted in higher springiness even after 7 days of short-term storage. These findings clarify how PHG redistributes dough components and reinforces gas cell walls, and provide a practical basis for improving the quality and storage stability of high-fiber whole wheat steamed bread.

In this study, whey protein isolate (WPI) and psyllium husk powder (PHP) were used as raw materials to prepare WPI-PHP composites, which were subsequently employed as emulsifiers to construct emulsion systems. The effects of PHP content (0-0.18%) and environmental pH (3-11) on the structural properties of the composites, as well as on the performance and stability of the resulting emulsions, were systematically investigated. The composites and emulsions were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), interfacial tension measurement, three-phase contact angle analysis, zeta potential, particle size analysis, rheological testing, and multi-stability assessment. The results indicate that polysaccharides and proteins form an ordered composite film at the oil-water interface through the synergistic effects of electrostatic, hydrogen bonding, and hydrophobic interactions. Under optimal conditions (0.09% polysaccharide content, pH 7), the emulsion exhibited the smallest particle size, the highest absolute zeta potential (approximately -30 mV), and an interfacial contact angle of 95.05°, indicating a moderately hydrophobic state favorable for long-term droplet stability. FTIR and XRD analyses confirmed that, under these conditions, the polysaccharides and proteins formed structurally ordered intermolecular complexes. Rheological analysis revealed that this emulsion system behaves as a viscous fluid with optimal energy dissipation capacity. Stability tests further confirmed that the optimized emulsion showed the smallest change in particle size after 28 days of storage at room temperature. It displayed no significant instability following thermal treatment (90 °C), freeze-thaw cycles, or pH adjustments, demonstrating exceptional tolerance to multiple environmental stresses. Notably, at the protein isoelectric point (pH 5), the emulsion particles were largest, the zeta potential was lowest, and the stability was poorest. In contrast, an excessive polysaccharide content (≥0.12%) increased the system's viscosity but impaired long-term storage stability by inducing interfacial reorganization and relaxation. In summary, this study identifies the optimal formulation conditions for WPI-PHP composite emulsions (0.09%PHP, pH 7) and elucidates the underlying mechanisms by which polysaccharide concentration and pH dynamically modulate interfacial structure and macroscopic properties through the regulation of intermolecular interactions. These findings provide both theoretical guidance and a practical basis for the design of highly efficient and stable natural emulsifier systems.

Drought-induced reduction in crop yield is becoming a serious threat worldwide, especially in arid to semiarid regions. The introduction of medicinal plants into cropping patterns in arid regions is a suitable alternative to conventional crops because of their high demand and market value. Keeping in view the situation, an experiment was planned under natural arid conditions to screen out the best psyllium varieties in less time for cultivation in arid regions. The experiment included three psyllium varieties (V1 = Gujrat isabgol-2, V2 = Vallabh isabgol and V3 = Jawahar isabgol-4) and three irrigation regimes (control = CK, partial rootzone drying = PRD and deficit irrigation = DI) and was carried out in a completely randomized design with eight replications. The results of our experiment revealed that although cell stress indicators (electrolyte leakage, relative cell injury, methylglyoxal, malondialdehyde, and hydrogen peroxide contents) were less and photosynthesis, water relationships, and membrane stability were greater in the control irrigation, the activities of enzymatic and nonenzymatic antioxidants were greater in the PRD and DI regimes. Among the water deficit treatments, more water potential, proline contents, ascorbic acid contents, membrane stability index, and yield were recorded in the PRD than in the DI. Among the varieties, V3 performed the best under water deficit conditions, whereas variety V2 presented the lowest values. It was concluded that under less water availability, the combination of the PRD with the variety V3 optimized physiological and yield outcomes by sustained higher relative water contents (77.10%), mesophyll conductance (0.67 mol CO2 m-2 s-1 bar-1), photosynthesis (15.10 µmol of CO2 m-2s-1), and membrane stability index (78.80%). Consequently, maximized water use efficiency (0.21 g L-1) and antioxidant activities, leading to higher yield (0.76 g plant-1). Future research should focus on integrating PRD with other water management techniques like mulching, osmoprotectants spray to enhance its efficacy under water deficit conditions.

This study investigates the potential of arabinoxylan-rich Psyllium Seed Hydrocolloid (PSH) as a bioink with enhanced pro-angiogenic potential for 3D bioprinting. PSH, derived from the Plantago ovata, is polysaccharide-based hydrocolloid with gel-forming ability. Here, aqueous extraction of PSH was done without post-processing to overcome the limitations caused by using toxic solvent. FTIR-ATR and SEM analyses were used to characterize extracted PSH bioink both chemically and morphologically. Arabinoxylan-rich PSH bioink showed a viscoelastic nature with shear-thinning ability, and high print-fidelity based on rheology and printability analyses, then optimal bioprinting parameters were determined to be 100 mg/mL, a 27G nozzle, and 10.5 psi. Further characterization was done by biodegradation and swelling tests, resulting in a 20.4-fold swelling ratio while gradual biodegradation was observed. Moreover, cell-laden structures were bioprinted using NIH-3T3 fibroblast cells, and homogeneous cell dispersion was visualized, with sustained cell viability and increased Collagen Type-I and F-actin expression observed over time. Besides, the pro-angiogenic potential of PSH was evaluated by an in ovo CAM assay, and increased vascular density was observed during embryonic development. Findings suggest that PSH is a promising bioink for bioprinting, supporting printability through enhanced viability, ECM production, and angiogenesis-associated behavior. Overall, this study integrates hydrocolloids with bioprinting, providing insights into eco-friendly, bioactive biomaterials for tissue engineering.

The gelation characteristics of surimi are a key determinant of the quality and functional performance of surimi-based products. This study examined how psyllium husk powder (PHP) modulates the gelation behavior, structural properties, and molecular interactions of myofibrillar protein (MP) extracted from unwashed surimi. Surimi gel and MP composites containing different PHP levels were evaluated using texture profile analysis, water-holding capacity, low-field nuclear magnetic resonance, differential scanning calorimetry, particle size distribution, turbidity and solubility assays, Fourier transform infrared spectroscopy, ultraviolet absorption spectroscopy, and scanning electron microscopy. PHP addition noticeably enhanced the structural integrity and water retention of surimi gels, resulting in denser and more cohesive networks with reduced cooking loss. Water mobility shifted toward more tightly bound states, accompanied by improved thermal stability. PHP promoted protein aggregation, as evidenced by increased particle size and turbidity and reduced solubility. Spectroscopic and molecular-force analyses revealed PHP-induced conformational rearrangements of MP, including decreased α-helix content, increased β-sheet structures, strengthened hydrophobic interactions and disulfide bonding, and adjustments in ionic and hydrogen bonding. Microstructural observations further showed that PHP effectively filled voids within the protein matrix and facilitated the formation of a more compact and continuous gel network. Overall, moderate PHP incorporation reinforced protein-polysaccharide interactions and improved the heat-induced gelation behavior of unwashed surimi. These findings highlight PHP as a functional bio-based additive with potential for engineering higher-quality, structurally stable surimi products.

BackgroundPatients receiving peritoneal dialysis (PD) often report problems with constipation. Constipation in PD is associated with increased risks of mechanical and infectious complications, such as poor drainage and fluid removal, catheter migration and peritonitis. A natural fibre supplement, psyllium husk, has been identified as a potential alternative therapy to minimise the risk of constipation for patients receiving PD.MethodsFIBRE-PD is a prospective parallel-arm open-label feasibility study in which patients on PD were 1:1 randomly assigned to receive either psyllium husk (intervention group) or continue routine Movicol[®] (control group) for four weeks (28 days). The primary outcome was feasibility, defined as successful recruitment of 60 patients, representing 70% of eligible PD patients. Secondary outcomes included adherence, retention, safety, bowel frequency and patient-reported outcomes (e.g., gastrointestinal symptom burden, quality of life).ResultsOverall, 96 patients were screened for eligibility. Sixty-six (69%) were deemed not eligible, mainly due to non-adherence to prescribed regular Movicol (n = 41, 62%). Among 30 eligible patients, 20 patients (67% of eligible population) were successfully recruited into the study. The intervention group demonstrated high retention (77%), adherence rates (78%) and significant improvement in gastrointestinal symptoms and quality of life compared to patients in the control group. No adverse outcomes were reported.ConclusionThe FIBRE-PD did not meet its original recruitment target due to an unexpectedly high number of ineligible patients. The recruited proportion almost reached the pre-specified target of 70% of eligible patients, and participants in the intervention group demonstrated high retention and adherence rates with observed benefits in gastrointestinal symptom burden and quality of life.

Irritable bowel syndrome (IBS) is a highly prevalent disorder of gut-brain interaction characterized by chronic abdominal pain associated with altered bowel habits, including constipation-predominant (IBS-C), diarrhea-predominant (IBS-D), mixed (IBS-M), and unsubtyped forms. The pathophysiology of IBS is believed to be multifactorial as it involves dysregulation of the gut-brain axis, visceral hypersensitivity, serotonergic imbalance, epithelial barrier dysfunction, immune activation, dysbiosis, bile acid alterations, in addition to psychosocial stressors. These interacting mechanisms are known to be involved in the generation of persistent symptoms as well as the widely reported clinical heterogeneity of the disease. Current management strategies include dietary modification, psychological therapies, microbiota-targeted approaches, and pharmacological agents targeting the prevalent symptom subtype. However, treatment responses remain variable, and many patients seek complementary and natural interventions to alleviate their symptoms. Emerging evidence suggests that natural products may exert therapeutic benefits through anti-inflammatory actions, modulation of serotonergic signaling, improvement of intestinal barrier integrity, microbiota regulation, and neuromodulatory effects. Clinical studies demonstrate that certain natural interventions, particularly peppermint oil, STW 5 (Iberogast), psyllium, and several selected probiotics, can provide modest but clinically meaningful symptom improvement, especially for abdominal pain. Nonetheless, heterogeneity in trial design, short durations, small sample sizes, and limited subtype stratification restrict the strength of the resulting recommendations. This review provides a comprehensive overview of IBS pathophysiology, current treatment strategies, and mechanistic and clinical evidence supporting natural products in IBS management, while highlighting critical gaps and future research priorities.

The human diet plays a pivotal role in health, yet many studies seeking to identify health-promoting foods rely on experimental designs that poorly reflect natural circumstances. The effects of dietary fibres on the microbiota are typically examined using pooled faecal material and isolated fibres, creating unrealistic environments. Additionally, little progress has been made in distinctly characterising the fermentation rates of dietary fibres. To evaluate the temporal dynamics of gut microbial composition and metabolite production, as well as to characterise the fermentation rates of dietary fibres at an individual level, we conducted an n-of-1 longitudinal study examining responses to eight distinct dietary fibres, fermented both individually and in combination. A blend of sugarcane fibre and cassava resistant starch produced significantly higher butyrate levels (p < 0.0001) than either fibre alone. Microbial profiling showed that inulin and pectin selectively enriched Bifidobacterium spp. Anaerobutyricum hallii was increased with psyllium husk, wheat dextrin, and banana resistant starch, but decreased with a mixture of sugarcane fibre and cassava resistant starch (p < 0.0001). Fermentation kinetics were distinctly categorised into "fast", "medium", "slow" and "poorly-fermentable". These findings indicate that combinations of dietary fibres can be used as a strategy to engineer synergistic health-promoting metabolite responses in an individual, while establishing a standardised framework for describing fermentation rates across studies.

Stabilizers are extensively employed in yogurts to enhance their textural properties. Recently, there has been a growing demand for natural, plant-derived stabilizers as these not only improve water-holding capacity, control syneresis, and regulate firmness-like textural properties but also their ability to enhance the nutritional value of yogurts. Plant stabilizers like gums and mucilages, including almond gum, psyllium husk gum, okra mucilage, flaxseed mucilage, quince seed mucilage, chia seed mucilage, and jujube mucilage, have successfully been revealed to improve water holding capacity of yogurt curd, and reducing syneresis by increasing the total solid content in yogurt. The anionic polysaccharides in these plant stabilizers interact with milk proteins, aided by calcium ions in milk, improving the gel structure. Neutral hydrocolloids also enhance yogurt viscosity, further contributing to improving the textural properties of yogurt. In contrast, aloe vera gel like plant sources which contain weak fibrous polysaccharides network and antimicrobial agents like salicylic acid, are less effective as stabilizers. Fibers from apple pomaces, orange peels, and passion fruit peels are excellent stabilizers due to their high pectin content. Excessive use of stabilizers however can result in textural defects. Thus, optimizing the amount of natural stabilizer is crucial to obtain optimal textural properties in yogurt. This review consolidates current research to serve as a comprehensive guide for yogurt manufactures, providing optimal usage levels for various plant stabilizers to achieve desirable texture and minimize syneresis without inducing other defects.

This review was conducted to examine the promising health benefits of psyllium, its therapeutic potential in relation to various chronic diseases, its mechanisms, and its possible side effects or toxicity; to explore its applications in food systems; to identify the positive and negative effects of its consumption; and to provide perspectives for future research and development efforts for psyllium.

The development of gluten-free (GF) bakery items is a technological and nutritional challenge due to the absence of gluten, a significant structural protein in conventional bakery products. Plant-derived hydrocolloids have appeared as functional additives capable of substituting for the role of gluten by enhancing dough rheology, water-holding capacity, texture, and shelf life. This review comprehensively categorizes and evaluates major plant-based hydrocolloids such as xanthan gum, guar gum, psyllium, flaxseed, chia, and locust bean gum. Their individual and collective effects on dough behavior, crumb texture, and sensory attributes are examined. Further, emerging patterns in hybrid hydrocolloid systems, clean-label product development, and sustainable sources are discussed. Constraints such as cost, formulation complexity, and low consumer acceptance of certain gums are also taken into account. Comparative tables and case studies describe the functionality of each hydrocolloid, giving practical details on formulation strategies. Future research must be directed toward application-specific optimization, safety regulations, and sensory acceptability to optimize the functionality of GF baked foods.

This study aimed to enhance the shelf-life and quality of Asian hard clam (HC) using pulsed electric field (PEF) pre-treatment, vacuum impregnation (VI), and natural additives. PEF-treated HC were infused with psyllium husk (PH, 0.5-2 %; w/v) or κ-carrageenan (KC, 0.5-2 %; w/v), in which 2 % PH yielded the highest weight gain and lowest cooking loss. HC was further treated with chitooligosaccharide-epigallocatechin gallate conjugate (CEC, 2-3 %; w/w) without and with PH, then stored at 4 °C for 15 days. Histology confirmed structural changes in the muscle by PEF, especially in combination with CEC and PH. Microbial counts in 3 % CEC-treated HC remained below 5 log CFU/g sample until day 12. Lipid oxidation was suppressed and fatty acid analysis showed preservation of PUFA. Integration of PEF pre-treatment with CEC and PH infusion preserved clams for 12 days with lower cooking and quality losses, indicating a synergistic effects on HC preservation during refrigerated storage.