Definition Of Dietary Fiber Research Articles

A review of current analytical methods for the determination of dietary fiber in food

Fiber benefits health and is an essential requirement in the body's daily diet. The definition of fiber has been evolving over the past 70 years. Initially, the definition of fiber focused only on plant cell walls (cellulose, hemicellulose, pectin, cutin, glycoprotein) and intracellular storage and secretion substances (gum, mucilage). More recently, the world has focused on resistant starch and oligosaccharides. The CODEX definition of dietary fiber includes all non-digestible carbohydrate polymers with a degree of polymerization of 3 or higher, provided that they benefit health. Fiber has many components, requiring the development of different methods to analyze components such as fructo-oligosaccharide, galacto-oligosaccharide, polydextrose, resistant maltodextrin, resistant starch, etc. A series of AOAC methods have been developed to explore different types of fiber, and these methods are still valid and widely used. For the analysis of total fiber content, the enzymemass method according to Prosky (AOAC 985.29) was considered the gold standard when it was first published. However, this method only determines a part of the fiber. When adding up the specific fiber components calculated from different methods, some types of fiber are double counting. Therefore, the method for determining total fiber is constantly updated and revised. The Enzymatic-Gravimetric-Liquid Chromatography method has been developed and can fully determine the components of dietary fiber; the newly published updated version is AOAC 2022.01.

Dietary fiber - a scoping review for Nordic Nutrition Recommendations 2023.

Dietary fiber is a term crudely defined as carbohydrates (CHOs) that escape digestion and uptake in the small intestine. Lignin, which is not a CHO, is also a part of the dietary fiber definition. Dietary fibers come in different sizes and forms, with a variety of combinations of monomeric units. Health authorities worldwide have for many years recommended a diet rich in dietary fibers based on consistent findings that dietary fibers are associated with reduced incidences of major non-communicable diseases, including obesity, type 2 diabetes, cardiovascular disease, and colorectal cancer. Most fibers come from common edible foods from the plant kingdom, but fibers are also found in food additives, supplements, and breast milk. The recommended intake in Nordic Nutrition Recommendations 2012 (NNR2012) is 25 g/d for women and 35 g/d for men, whereas the actual intake is significantly lower, ranging from 16 g/d to 22 g/d in women and 18 g/d to 26 g/d in men. New studies since NNR2012 confirm the current view that dietary fiber is beneficial for health, advocating intakes of at least 25 g/day.

Intake and sources of dietary fibre and dietary fibre fractions in Finnish children.

The current definition of dietary fibre was adopted by the Codex Alimentarius Commission in 2009, but implementation requires updating food composition databases with values based on appropriate analysis methods. Previous data on population intakes of dietary fibre fractions are sparse. We studied the intake and sources of total dietary fibre (TDF) and dietary fibre fractions insoluble dietary fibre (IDF), dietary fibre soluble in water but insoluble in 76 % aqueous ethanol (SDFP) and dietary fibre soluble in water and soluble in 76 % aqueous ethanol (SDFS) in Finnish children based on new CODEX-compliant values of the Finnish National Food Composition Database Fineli. Our sample included 5193 children at increased genetic risk of type 1 diabetes from the Type 1 Diabetes Prediction and Prevention birth cohort, born between 1996 and 2004. We assessed the intake and sources based on 3-day food records collected at the ages of 6 months, 1, 3 and 6 years. Both absolute and energy-adjusted intakes of TDF were associated with age, sex and breast-feeding status of the child. Children of older parents, parents with a higher level of education, non-smoking mothers and children with no older siblings had higher energy-adjusted TDF intake. IDF was the major dietary fibre fraction in non-breastfed children, followed by SDFP and SDFS. Cereal products, fruits and berries, potatoes and vegetables were major food sources of dietary fibre. Breast milk was a major source of dietary fibre in 6-month-olds due to its human milk oligosaccharide content and resulted in high SDFS intakes in breastfed children.

Comparative analysis of dietary fibre determination by AOAC 991.43 and AOAC 2011.25 for frequently consumed foods in Slovenia

The definition of dietary fibre was modified by Codex Alimentarius commission in 2009, and now includes low molecular weight soluble dietary fibre. This prompted the development of new methods for determination of dietary fibre, such as AOAC 2009.01 and AOAC 2011.25. We compared the dietary fibre contents of 45 different foods from six food groups, as sources of dietary fibre frequently consumed in Slovenia. Dietary fibre was determined with methods AOAC 991.43 and AOAC 2011.25, and the results were compared. Majority of results show significantly higher dietary fibres when determined using AOAC 2011.25. Differences can be explained by low molecular weight soluble dietary fibre, which is measured by AOAC 2011.25. New methods for dietary fibre determination have impacts on national food composition databases, which remain mainly based on AOAC 991.43; defining the need to update food composition databases with data that include low molecular weight soluble dietary fibre.

Alpha-Cyclodextrin Attenuates the Glycemic and Insulinemic Impact of White Bread in Healthy Male Volunteers.

The demonstration of a physiological benefit has recently become an indispensible element of the definition of dietary fibers. In the here-reported pilot study, the effect of alpha-cyclodextrin (alpha-CD) on the postprandial glycemic and insulinemic effect of starch was examined. Twelve fasted, healthy male volunteers received, on three subsequent days, a test breakfast consisting of (A) 100 g fresh white bread (providing 50 g starch) and 250 mL drinking water, (B) the same bread with a supplement of 10 g alpha-CD dissolved in the drinking water, and (C) 25 g alpha-CD dissolved in drinking water. Capillary and venous blood was sampled before the breakfast and in regular intervals for a three-hour period thereafter. Glucose was determined in capillary blood and insulin in the plasma of venous blood samples. Breakfast (A) led to a rapid rise in blood glucose and insulin. In breakfast (B), alpha-CD reduced the areas under the curve of blood glucose and insulin significantly by 59% and 57%, respectively, demonstrating that alpha-CD inhibits and thereby delays starch digestion. Treatment (C) was not associated with a rise of blood glucose. Hence, alpha-CD complies with the current definition of dietary fiber in every respect.

FRIED FOOD AND POSSIBLE HEALTH HAZARDS

FRIED FOOD AND POSSIBLE HEALTH HAZARDS

Comparison and Optimization of Different Protein Nitrogen Quantitation and Residual Protein Characterization Methods in Dietary Fiber Preparations.

Proteins are plant cell wall components but they are not included in the definition of dietary fiber. Therefore, dietary fiber preparations have to be corrected for their residual protein contents. This is commonly done by calculating the residual protein concentrations from the nitrogen contents after Kjeldahl digestion. Here, three different methods to determine nitrogen in Kjeldahl digests were compared: conventional titration with hydrochloric acid after steam distillation, a colorimetric assay (24-well microplates and cuvettes), and the determination by using an ammonia electrode. All assays gave similar results but detection using the ammonia electrode was found to be the most time-efficient approach. Also, an amino-acid profiling method, which is not based on commercial kits and which is suitable for routine analysis of dietary fiber preparations, was established. For this purpose, an HPLC-FLD method following amino acid derivatization using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) was optimized for fiber samples. Although all commonly used dietary fiber preparation methods involve the application of proteases the amino acid profiles of fiber samples from different sources were shown to be quite diverse. Considering the amino acid composition of the residual protein in various dietary fiber preparations, residual protein is probably not only based on structural proteins.

Perspective: Physiologic Importance of Short-Chain Fatty Acids from Nondigestible Carbohydrate Fermentation

ABSTRACTIn recent years, it has become increasingly obvious that dietary fiber or nondigestible carbohydrate (NDC) consumption is critical for maintaining optimal health and managing symptoms of metabolic disease. In accordance with this, the US FDA released its first official definition of dietary fiber in 2016 for regulation of Nutrition and Supplement Facts labels. Included in this definition is the requirement of an isolated or synthetic NDC to produce an accepted physiologic health benefit, such as improved laxation or reduced fasting cholesterol concentrations, upon consumption. Even though NDC fermentation and production of short-chain fatty acids elicit many physiologic effects, including serving as a source of energy for colonocytes, curbing glycemic response and satiety, promoting weight loss, enhancing mineral absorption, reducing systemic inflammation, and improving intestinal health, the process of fermentation is not considered a physiologic endpoint. Instead, expensive and laborious clinical trials must be conducted and an accepted physiologic benefit observed. In this review, we discuss the physiologic importance of NDC fermentation through extensive examination of clinical evidence and propose that the degree of fermentability of an NDC, rather than the endpoints of a clinical trial, may be appropriate for classifying it as a dietary fiber.

Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health.

Research into the analysis, physical properties and health effects of dietary fibre has continued steadily over the last 40-50 years. From the knowledge gained, countries have developed guidelines for their populations on the optimal amount of fibre to be consumed each day. Food composition tables from many countries now contain values for the dietary fibre content of foods, and, from these, combined with dietary surveys, population intakes have been determined. The present review assessed the uniformity of the analytical methods used, health claims permitted, recommendations and intakes, particularly from national surveys across Europe and around the world. It also assessed current knowledge on health effects of dietary fibre and related the impact of different fibre types on health. The overall intent was to be able to provide more detailed guidance on the types of fibre which should be consumed for good health, rather than simply a total intake figure, the current situation. Analysis of data indicated a fair degree of uniformity in the definition of dietary fibre, the method used for analysis, the recommended amount to be consumed and a growing literature on effects on digestive health and disease risk. However, national dietary survey data showed that intakes do not reach recommendations and very few countries provide guidance on the types of fibre that are preferable to achieve recommended intakes. Research gaps were identified and ideas suggested to provide information for more detailed advice to the public about specific food sources that should be consumed to achieve health benefits.

Challenges and opportunities in the use of low‐energy sugar replacers

Challenges and opportunities in the use of low‐energy sugar replacers

A Brief Overview and Comparison of Global Fiber Regulations

Dietary fiber, which has a long history of scientific research, has been identified as a nutrient that is often underconsumed. This was most recently noted in the 2015 U.S. Department of Agriculture Dietary Guidelines for Americans. Dietary fiber encompasses a diverse group of carbohydrate compounds with a variety of structures and functional properties. There has been a general understanding about which carbohydrates constitute a dietary fiber based on composition and physiological effects. Analytical methods have been developed and are relied on to classify dietary fibers and demonstrate resistance to digestion in the small intestine. However, simply having the ability to measure the presence of compounds that are resistant to digestion may not be adequate. The current Codex definition of dietary fiber promotes the concept that compounds that behave like fiber in vivo, regardless of source, can be considered dietary fiber provided that physiological health benefits can be shown. In general, the health b...

Dietary Fiber Analysis of Four Pulses Using AOAC 2011.25: Implications for Human Health.

Chickpeas, common beans, dry peas, and lentils are pulse crops that have been a cornerstone of the human diet since the inception of agriculture. However, the displacement of pulses from the diet by low fiber protein alternatives has resulted in a pervasive deficiency referred to as the dietary fiber gap. Using an analytical method American Association of Analytical Chemists (AOAC) 2011.25 that conforms to the Codex Alimentarius Commission consensus definition for dietary fiber, the fiber content of these pulse crops was evaluated in seed types used for commercial production. These pulse crops have 2 to 3 times more fiber per 100 g edible portion than other dietary staples. Moreover, there is marked variation in fiber content among cultivars of the same crop. We conclude that pulse crop consumption should be emphasized in efforts to close the dietary fiber gap. The substantial differences in fiber content among currently available cultivars within a crop can be used to further improve gains in fiber intake without the need to change dietary habits. This provides a rationale for cultivar-based food labeling.

New dietary fibre content results for cereals in the Nordic countries using AOAC 2011.25 method

The definition of dietary fibre (DF) has been revised, and an analytical method AOAC 2011.25 is based on the updates. DF content and monosaccharide composition in composite samples from Swedish, Norwegian, Estonian and Finnish wholegrain wheat flour, rye flour and rolled oats were analysed and compared. Furthermore, DF amounts of 11 industrial and 6 commercial Finnish cereal products were analysed. New DF results are needed, since the national Food Composition Databases (FCDBs) currently contain DF values obtained using older methods underestimating some DF components, such as resistant starch and non-digestible oligosaccharides. The total DF amounts of rolled oats and rye flour were similar among countries, but variation was found in wholegrain wheat flour. The analysed cereal products contained 0.2–5.7g/100g oligosaccharides (SDFS), with the highest level in rye bran. Wheat and rye bran were found to be the best sources for total DF (46 and 32g/100g, respectively), wheat bran was a superior source for water-insoluble DF (IDF; 41g/100g), whereas oat bran was found to contain the most water-soluble high molecular weight DF (SDFP; 6g/100g). These new analytical results for total DF are higher than currently presented in FCDBs.

Fermentable Carbohydrates Differentially Affect Colon Tumor Formation in Azoxymethane-Induced Male Fischer 344 Rats

Background: The role of fermentation compared with the source or type of the fermentable material in colon tumorigenesis remains an issue in refining the definition of dietary fiber (DF).Objective: The aim of this study was to investigate the fermentation and source-specific effects of various carbohydrates in a medium-term colon tumorigenesis model.Methods: Six-week-old male Fischer 344 rats were randomly allocated into 6 groups (n = 36/group) to receive either AIN-93G (control) or diets containing fructooligosaccharides, wheat bran (WB), oat bran (OB), polydextrose, or high-amylose maize starch (HAMS), each adjusted to contain a total DF concentration of 7% (wt:wt) and have a fermentability of 3% (wt:wt). After 2 wk, 24 rats/group received 2 subcutaneous doses of azoxymethane (at 15 mg/kg body weight) 1 wk apart while 12 rats/group were injected with a saline vehicle; all rats were maintained on the assigned diets for 24 wk postinjection and then killed. Colon tumor outcomes and pathology together with cecal short-chain fatty acid composition were assessed.Results: No tumors were found in saline-injected rats, and all subsequent analyses were restricted to azoxymethane-injected rats. Colon tumor incidence was significantly lower in the polydextrose (21%) and WB (13%) groups than in the control group (63%; P < 0.05) but not different from the fructooligosaccharide (58%), HAMS (46%), and OB (33%) groups. In comparison to the control group (8 proximal/31 total tumors), fermentable materials reduced the number of tumors (P < 0.05) originating in the proximal colon: HAMS (5/15), polydextrose (2/7), OB (2/9), fructooligosaccharides (1/21), and WB (1/3). The mean ± SEM number of tumors/tumor-bearing rats was significantly lower in the WB (1.00 ± 0.00), OB (1.13 ± 0.13), and HAMS (1.36 ± 0.15) groups than in the control group (2.07 ± 0.27; P < 0.02); other groups did not differ. The mean ± SEM tumor burden/diet group was lower in the WB (1.2 ± 0.7 mm2), polydextrose (6.7 ± 3.2 mm2), and OB (7.0 ± 3.0 mm2) groups than in the control (21.4 ± 5.9 mm2) and fructooligosaccharide (22.1 ± 7.1 mm2; P < 0.05) groups but not significantly different from the HAMS group (15.1 ± 6.1 mm2). Total cecal SCFA concentrations did not differ among diet groups (overall mean ± SEM: 81 ± 4 μmol/g wet weight).Conclusion: The rate and extent of fermentation of the carbohydrate material as well as the characteristics of the material in the lumen of the lower gastrointestinal tract all appear to have an important role in tumor outcomes in the azoxymethane-induced rat colon tumorigenesis assay.

New Horizons for the Study of Dietary Fiber and Health: A Review.

Dietary fibre has been consumed for centuries with known health benefits, but defining dietary fibre is a real challenge. From a functional perspective, dietary fibre is described as supporting laxation, attenuating blood glucose responses and assisting with cholesterol lowering. The problem is different types of dietary fibre have different effects, and new effects are increasingly observed, such as the influence on gut microbiota. Thus, a single definition may need to be described in more generic terms. Rather than being bound by a few functional definitions, we may need to embrace the possibilities of new horizons, and derive a working definition of dietary fibre based on a set of conceptual principles, rather than the limited definitions we have to date. To begin this process, a review of individual fibre types and their physiological effects would be helpful. Dietary fibre is a complex group of substances, and there is a growing interest in specific effects linked to fibre type. Different fractions of dietary fibre have different physiological properties, yet there is a paucity of literature covering the effects of all fibres. This paper describes a range of individual fibre types and identifies gaps in the literature which may expose new directions for a working definition of dietary fibre.

Dietary fibre and health in children and adolescents.

The role of dietary fibre in promoting sustained health has been studied for several decades and in adults there is good evidence that diets rich in high-fibre foods reduce the risk of chronic diseases, including CVD and cancer. Research in this area, however, has been hampered by uncertainties about the definition of dietary fibre which has resulted in many studies measuring fibre in different ways. There is also a wide range of properties and actions of different fibres in the human body, depending on their solubility, viscosity and fermentability by the colonic microbiota. This review considers the epidemiological evidence for dietary fibre and health in children and the current dietary recommendations and measured intakes in several countries using national surveys. In children and adolescents, there is a particular lack of relevant research on which to formulate appropriate dietary fibre recommendations and these are often based on extrapolation from adult data. However, children are not little adults and have differing physiology and nutritional needs as they grow. The dietary recommendations in different countries are based on varying premises and daily amounts. Intakes vary from country to country and on the whole do not meet recommendations. Much more research is needed in children to fully understand the impact of dietary fibre on growth and health in the young to allow more appropriate recommendations to be made.

Determination of total dietary fibre and available carbohydrates: A rapid integrated procedure that simulates in vivo digestion

The new definition of dietary fibre introduced by Codex Alimentarius in 2008 includes resistant starch and the option to include non‐digestible oligosaccharides. Implementation of this definition required new methodology. An integrated total dietary fibre method was evaluated and accepted by AOAC International and AACC International (AOAC Methods 2009.01 and 2011.25; AACC Method 32–45.01 and 32–50.01, and recently adopted by Codex Alimentarius as a Type I Method. However, in application of the method to a diverse range of food samples and particularly food ingredients, some limitations have been identified. One of the ongoing criticisms of this method was that the time of incubation with pancreatic α‐amylase/amyloglucosidase mixture was 16 h, whereas the time for food to transit through the human small intestine was likely to be approximately 4 h. In the current work, we use an incubation time of 4 h, and have evaluated incubation conditions that yield resistant starch and dietary values in line with ileostomy results within this time frame. Problems associated with production, hydrolysis and chromatography of various oligosaccharides have been addressed resulting in a more rapid procedure that is directly applicable to all foods and food ingredients currently available.

CODEX-aligned dietary fiber definitions help to bridge the 'fiber gap'.

A comprehensive dietary fiber (DF) definition was adopted by the CODEX Alimentarius Commission (CAC) (1) to reflect the current state of knowledge about DF, (2) to recognize that all substances that behave like fiber regardless of how they are produced can be named as DF if they show physiological benefits, and (3) to promote international harmonization for food labeling and food composition tables. This review gives the history and evolution of the state of DF knowledge as looked at by refinements in DF methods and definitions subsequent to the launch of the DF hypothesis. The refinements parallel both interventional and epidemiological research leading to better understanding of the role of DF in contributing to the numerous physiological benefits imparted by all the various digestion resistant carbohydrates. A comparison of the CODEX definition (including its footnote that authorizes the inclusion of polymers with DP 3–9) and approved CODEX Type 1 methods with other existing definitions and methods will point out differences and emphasize the importance of adoption of CODEX-aligned definitions by all jurisdictions. Such harmonization enables comparison of nutrition research, recommendations, food composition tables and nutrition labels the world over. A case will be made that fibers are analogous to vitamins, in that they vary in structure, function and amount needed, but each when present in the right amount contributes to optimal health. Since the intake of DF is significantly below recommended levels throughout the world, the recognition that ‘all fibers fit’ is an important strategy in bridging the ‘fiber gap’ by enfranchising and encouraging greater intake of foods with inherent and added DF. Fortifying foods with added DF makes it easier to increase intakes while maintaining calories at recommended levels.

Dietary Fiber Methods in Codex Alimentarius: Current Status and Ongoing Discussions

Currently there are multiple Type I methods for dietary fiber analysis, which conflicts with the principles of the Codex Procedural Manual. While not ideal, the Committee on Methods of Analysis and Sampling (CCMAS) is using the most recent scientific evidence to simplify and aid those involved in dietary fiber testing. The Codex Alimentarius is progressing using input from experts in dietary fiber method research. Harmonizing an internationally accepted definition for dietary fiber has been a large undertaking. Some authorities have accepted this fairly recent definition, whereas others have not commented on the topic for a number of years. To ensure the most appropriate test method is used, analysts, laboratory managers, and others analyzing foods for dietary fiber need to understand how and where the results from the testing will be used and any legal implications that may arise. While the Codex Alimentarius Commission (CAC) is working toward a single analytical method commensurate with its definition, ...

Codex dietary fibre definition – Justification for inclusion of carbohydrates from 3 to 9 degrees of polymerisation

The main controversy about the DF definition, adopted by the commission of Codex Alimentarius, refers to the inclusion of carbohydrates of 3–9 degrees of polymerisation (DP), decision which may be made individually by the authorities of each country. Due to the possibility of having two definitions and the negative impact it would cause over the harmonisation of nutritional information, a bibliographic review was carried, from 2009 to 2011, aiming to gather justifications for the inclusion of carbohydrates of 3–9 DP in the definition. The current review presents scientific bases that are directed to three topics: physiological aspects; repercussion over the analytical method; and impact on consumers and other users. The decision of including unavailable carbohydrates of 3–9 DP in the definition of DF may cause effective global harmonisation in the nutritional labelling, considering that the main goal is to help consumers choose healthy foods.