Recomendaciones y efectos de la fibra dietaria en niños / Recommendations and effects of dietary fiber for children

Conocida es la influencia de la fibra dietaria sobre los efectos mecánicos a nivel gastrointestinal, la composición y modulación de la microbiota intestinal y su función en la actividad metabólica y nutricional en adultos. En niños y adolescentes estos efectos son menos conocidos, generando interesantes áreas de investigación y desarrollo científico que nos puedan entregar mayor conocimiento de sus repercusiones a nivel fisiológicos y fisiopatológicos. Esta revisión tiene como objetivo entregar información actualizada sobre las diferentes clasificaciones de fibra, sus principales funciones digestivas y metabólicas, así como las recomendaciones de ingesta diaria en pediatría.

Among adults, the influence of dietary fiber on mechanical effects at the gastrointestinal level, the composition and modulation of the intestinal microbiota and function in the metabolic and nutritional activity is known. However, in children and adolescents, these effects are less known, generating interesting areas of research and development that could provide additional knowledge at the physiological and pathophysiological level. The aim of this review was to provide updated information about the different classifications of fiber, the principal digestive and metabolic functions, as well as recommendations for daily intake for pediatric populations.

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.

Fibra dietaria: nuevas definiciones, propiedades funcionales y beneficios para la salud: revisión / Dietary fiber: new definitions, functional properties and health benefits

En los últimos diez años hubo importantes modificaciones en la definición de la fibra dietaria bajo la dirección de la Comisión del CODEX Alimentarius. El más importante fue la inclusión de los carbohidratos no digeribles de 3 a 9 unidades de grado de polimerización dentro de la definición química, la que fue adoptada algunos países y en otras están en proceso de evaluación tal como los Estados Unidos; lo que hace que no exista un consenso global. Donde sí hay un consenso es en la definición fisiológica de la fibra dietaria, considerada como grupo de carbohidratos resistentes a la digestión por las enzimas del intestino delgado y fermentado en forma parcial o total en el colon, con efectos favorables en la salud. La Association of Official Analytical Chemist (siglas en Inglés: AOAC), en armonía con la nueva definición del CODEX Alimentarius, establecieron los métodos AOAC 2009.01 y 2011.25, diseñado para cuantificar la fibra dietaria solubles, fibra dietaria insoluble y la fibra dietaria total. En este contexto, se vienen desarrollando investigaciones in vitro e in vivo (en animales y humanos) para demostrar los efectos fisicoquímicos, funcionales y fisiológicos que van orientados hacia la prevención y tratamiento de algunas enfermedades no transmisible (ENTs). La presente revisión, pretende informar de las nuevas definiciones y los métodos de análisis, las propiedades funcionales y fisiológicas de la fibra dietaria y sus efectos en la salud humana(AU)

In the last ten years there have been important changes in the definition of dietary fiber under the leadership of the CODEX Alimentarius Commission. The most important was the inclusion of non-digestible carbohydrates of 3 to 9 units of degree of polymerization within the chemical definition, which was adopted in some countries and in others are in the process of evaluation such as the United States which indicates that does not exist a global consensus. Where there is a consensus is in the physiological definition of dietary fiber, considered as a group of carbohydrates resistant to the digestion by enzymes of the small intestine and fermented partially or totally in the colon, with favorable health effects. The Association of Official Analytical Chemists (AOAC), in line with the new definition of CODEX Alimentarius, established the AOAC 2009.01 and 2011.25 methods, designed to quantify soluble dietary fiber, insoluble dietary fiber and total dietary fiber. In this context, In Vitro and In Vivo research (in animals and humans) are being carried out to demonstrate the physicochemical, functional and physiological effects that are directed towards the prevention and treatment of some non-communicable diseases (NCDs). This review aims to inform the new definitions and methods of analysis, the functional and physiological properties of dietary fiber and their effects on human health(AU)

A Critical Look at Prebiotics Within the Dietary Fiber Concept.

This article reviews the current knowledge of the health effects of dietary fiber and prebiotics and establishes the position of prebiotics within the broader context of dietary fiber. Although the positive health effects of specific fibers on defecation, reduction of postprandial glycemic response, and maintenance of normal blood cholesterol levels are generally accepted, other presumed health benefits of dietary fibers are still debated. There is evidence that specific dietary fibers improve the integrity of the epithelial layer of the intestines, increase the resistance against pathogenic colonization, reduce the risk of developing colorectal cancer, increase mineral absorption, and have a positive impact on the immune system, but these effects are neither generally acknowledged nor completely understood. Many of the latter effects are thought to be particularly elicited by prebiotics. Although the prebiotic concept evolved significantly during the past two decades, the line between prebiotics and nonprebiotic dietary fiber remains vague. Nevertheless, scientific evidence demonstrating the health-promoting potential of prebiotics continues to accumulate and suggests that prebiotic fibers have their rightful place in a healthy diet.

[Fiber-type indication among different pathologies]. / INDICACIONES DE DIFERENTES TIPOS DE FIBRA EN DISTINTAS PATOLOGÍAS.

INTRODUCTION: Fiber definition includes all those carbohydrates which are not digested nor absorbed in the upper gastrointestinal tract allowing them to reach the colon with no previous processing. Traditionally fiber has been classified according to their solubility into soluble and insoluble and different physiological properties have been defined for each type. The physiologic role of the fiber intake has been studied in diabetes, dyslipidemia or obesity. Fiber intake has also demonstrated to be beneficial in the prevention of many neoplastic diseases like colorectal cancer. It´s also known that fiber plays an important role in the faecal excretion of nitrogen. AIM: To evaluate the current evidence that fiber intake plays in the management and prevention of several different diseases, being able to determine, if possible, the most recommended fiber type for each clinical condition. METHODS: A non-systematic review by searching the Medline and Pubmed was made and studies which met the inclusion criteria were identified and selected for analysis. RESULTS: Different fiber types can be useful for the treatment of several gastrointestinal diseases like constipation, diarrhea, irritable bowel syndrome, ulcerative colitis remission or short bowel syndrome. Patients diagnosed with diabetes, obesity, hyperlipidemia, hypertension and other cardiometabolic diseases can get a clinical improvement with soluble fiber intake. Dietary fiber has demonstrated to play a role in the prevention of colorrectal cancer and other neoplastic diseases. Patients with hepatic encephalopathy or chronic kidney disease will also benefit from fermentable fiber intake. DISCUSSION: Fiber plays an important role in the prevention and treatment of many clinical conditions. However further investigations are needed to establish specific fiber intake recommendations.

Introducción: la fibra engloba los carbohidratos no digeridos ni absorbidos en el tubo digestivo, llegando intactos al colon. Se clasifica en soluble e insoluble, con propiedades fisiológicas distintas. La fibra se ha empleado frecuentemente para tratar y prevenir diversas patologías gastrointestinales. También se ha estudiado su papel en la fisiopatología de enfermedades como la diabetes, la dislipemia, la hipertensión arterial y la obesidad. Además se ha relacionado su consumo con la prevención de ciertos tumores, en especial del cáncer colorrectal, así como con el aumento de la excreción de nitrógeno en heces. Objetivos: analizar la evidencia del papel que la fibra puede tener en el tratamiento y prevención de distintas enfermedades, así como el tipo de fibra más adecuado en cada una. Métodos: revisión no sistemática en Medline y Pubmed, y posterior aplicación de los criterios de inclusión y exclusión. Resultados: diferentes tipos de fibra pueden ser útiles en el tratamiento de enfermedades gastrointestinales, como el estreñimiento, la diarrea, el síndrome de intestino irritable, la colitis ulcerosa en remisión o el síndrome de intestino corto. Los pacientes con diabetes, obesidad, hiperlipidemia, hipertensión y enfermedad cardiovascular también pueden beneficiarse del consumo principalmente de fibra soluble. La fibra alimentaria ha demostrado prevenir el cáncer de colon y otros tumores. En pacientes con encefalopatía hepática o insuficiencia renal, la fibra fermentable ha demostrado beneficios. Conclusiones: la fibra tiene un papel importante en la prevención y tratamiento de múltiples enfermedades; sin embargo, son necesarios más estudios de calidad para poder realizar recomendaciones más específicas.

Sickness behavior induced by endotoxin can be mitigated by the dietary soluble fiber, pectin, through up-regulation of IL-4 and Th2 polarization.

Peripheral activation of the immune system by infectious agents triggers the brain-cytokine system causing sickness behaviors which profoundly impact well-being. Dietary fiber is a beneficial foodstuff that, from a gastrointestinal tract perspective, exists in both insoluble and soluble forms. We show that a diet rich in soluble fiber protects mice from endotoxin-induced sickness behavior by polarizing mice Th2 when compared to a diet containing only insoluble fiber. Mice fed soluble fiber became less sick and recovered faster from endotoxin-induced sickness behaviors than mice fed insoluble fiber. In response to intraperitoneal endotoxin, mice fed soluble fiber had up-regulated IL-1RA and reduced IL-1beta and TNF-alpha in the brain as compared to mice fed insoluble fiber. Importantly, mice fed soluble fiber had a basal increase in IL-4 in the ileum and spleen which was absent in MyD88 knockout mice. Con-A stimulated splenocytes from mice fed soluble fiber showed increased IL-4 and IL-5 and decreased IL-2, IL-12 and IFN-gamma when compared to mice fed insoluble fiber. Likewise, endotoxin-stimulated macrophages from mice fed soluble fiber demonstrated decreased IL-1beta, TNF-alpha, IFN-gamma, IL-12 and nitrate and increased IL-1RA, arginase 1 and Ym1 when compared to mice fed insoluble fiber. Finally, the behavioral protection afforded by feeding mice soluble fiber was reduced in IL-4 knockout mice, as was the impact of soluble fiber on Con-A stimulated splenocytes and endotoxin activated macrophages. These data show that a diet rich in soluble fiber protects against endotoxin-induced sickness behavior by polarizing mice Th2 and promoting alternative activation of macrophages.

Effects of dietary fiber and its components on metabolic health.

Dietary fiber and whole grains contain a unique blend of bioactive components including resistant starches, vitamins, minerals, phytochemicals and antioxidants. As a result, research regarding their potential health benefits has received considerable attention in the last several decades. Epidemiological and clinical studies demonstrate that intake of dietary fiber and whole grain is inversely related to obesity, type two diabetes, cancer and cardiovascular disease (CVD). Defining dietary fiber is a divergent process and is dependent on both nutrition and analytical concepts. The most common and accepted definition is based on nutritional physiology. Generally speaking, dietary fiber is the edible parts of plants, or similar carbohydrates, that are resistant to digestion and absorption in the small intestine. Dietary fiber can be separated into many different fractions. Recent research has begun to isolate these components and determine if increasing their levels in a diet is beneficial to human health. These fractions include arabinoxylan, inulin, pectin, bran, cellulose, ß-glucan and resistant starch. The study of these components may give us a better understanding of how and why dietary fiber may decrease the risk for certain diseases. The mechanisms behind the reported effects of dietary fiber on metabolic health are not well established. It is speculated to be a result of changes in intestinal viscosity, nutrient absorption, rate of passage, production of short chain fatty acids and production of gut hormones. Given the inconsistencies reported between studies this review will examine the most up to date data concerning dietary fiber and its effects on metabolic health.

Papel das fibras alimentares sobre o controle glicêmico, perfil lipídico e pressão arterial em pacientes com diabetes melito tipo 2 / The role of dietary fibers on glycemic control, lipid profile, and blood pressure in type 2 diabetic patients

O diabetes melito (DM), cuja forma mais prevalente é o DM tipo 2, acomete mais de 5% da população mundial. Pacientes com DM podem apresentar complicações crônicas micro- e macrovasculares, sendo possível prevenir ou impedir a progressão destas complicações com medicamentos e mudanças de estilo de vida, que incluem prática de atividade física regular e adoção de uma dieta saudável. O objetivo deste manuscrito foi revisar os principais efeitos da ingestão de fibras sobre o controle glicêmico, perfil lipídico e pressão arterial em pacientes com DM tipo 2. Também foi revisada a definição das fibras. As fibras alimentares, em especial as fibras solúveis, têm comprovadamente um papel importante no manejo do DM tipo 2, apresentando efeitos benéficos sobre a homeostase glicêmica, perfil lipídico e hipertensão arterial. Adicionalmente, as fibras insolúveis contribuem para perda de peso, através de ação no mecanismo de saciedade, promovendo também melhora do controle metabólico nesses pacientes. Em conclusão, para atingir a recomendação diária de 14 g de fibras/1000 kcal, deve-se estimular o consumo de fibras em pacientes com DM tipo 2, tanto a partir da ingestão de alimentos fonte, como frutas, cereais integrais, verduras, legumes e leguminosas, como através de suplementos.

Diabetes mellitus (DM), whose most prevalent form is type 2 DM, affects more than 5% of the world population. Patients with DM may have chronic micro- and macrovascular complications. It is possible to prevent or halt the progression of these complications with medications and lifestyle changes that include regular physical activity and adopting of a healthy diet. The aim of this study was to review the main effects of fiber intake on glycemic control, lipid profile, and blood pressure in patients with type 2 DM. The definition of dietary fiber was also reviewed. Dietary fibers, particularly soluble fibers, have played an important role in the management of type 2 DM, with beneficial effects on glucose homeostasis, lipid profile and hypertension. Additionally, insoluble fibers contribute to weight loss by their influence on satiety, as well as by improving metabolic control. In conclusion, in order for patients with type 2 DM to reach the recommendation of 14 g of fiber/1000 kcal /day, consumption of fibers should be stimulated, both from natural food sources like fruits, whole grains, vegetables and legumes, and also from supplements.

Dietary glycemic index and the risk of age-related macular degeneration.

BACKGROUND: Dietary factors are known risk factors for age-related macular degeneration (AMD) -- the leading cause of visual loss among persons aged > or =65 y. High-glycemic-index diets have been hypothesized as a risk factor for AMD, but prospective data are unavailable. OBJECTIVE: The objective was to examine the association between dietary glycemic index and the 10-y incidence of AMD in the Blue Mountain Eye Study population. DESIGN: This was a population-based cohort study with 3,654 participants (> or =49 y) examined at baseline (1992-1994); 2,335 patients were reexamined after 5 y and 1952 after 10 y. The Wisconsin System was used to grade 10-y incident early and late AMD from retinal photographs. A food-frequency questionnaire was used to collect dietary information at baseline, and an Australian database was used to calculate the mean glycemic index. RESULTS: Over 10 y, 208 of 1,810 persons (cumulative incidence: 14.1%) developed early AMD. After age, smoking, other risk factors, and dietary constituents were adjusted for, a higher mean dietary glycemic index was associated with an increased 10-y risk of early AMD in a comparison of quartiles 1 and 4 [relative risk (RR): 1.77; 95% CI: 1.13, 2.78; P for trend = 0.03]. Conversely, a greater consumption of cereal fiber (RR: 0.68; 95% CI: 0.44, 1.04; P for trend = 0.05) and breads and cereals (predominantly lower glycemic index foods such as oatmeal) (RR: 0.67; 95% CI: 0.44, 1.02; P for trend = 0.03) was associated with a reduced risk of incident early AMD. No relation was observed with late AMD. CONCLUSIONS: A high-glycemic-index diet is a risk factor for early AMD -- the recognized precursor of sight-threatening late AMD. Low-glycemic-index foods such as oatmeal may protect against early AMD.

Classificação de coeficientes de variação na experimentação com nutrição de eqüinos / Classification of the coefficient of variation in experimentation with equine nutrition

Foi realizada a classificação de coeficientes de variação dos coeficientes de digestibilidade da matéria seca, matéria orgânica, proteína bruta, fibras em detergente neutro e ácido, energia bruta, fibra bruta, celulose, hemicelulose, lignina, extrato etéreo e ganho de peso diário, com base em artigos científicos e teses em eqüinocultura. Os coeficientes de variação foram classificados em: baixo [<(m-1DP)]; médio [(m-1D)(m+2DP)]. Todas as respostas medidas apresentaram distribuição normal pelo teste Lilliefors. Quanto aos coeficientes de digestibilidade da fibra em detergente neutro e celulose, houve concordância entre a classificação proposta e a sugerida na literatura, sendo os mais discrepantes os coeficientes de digestibilidade da energia bruta e lignina. Desse modo, para cada variável analisada existe distribuição diferenciada dos coeficientes de variação, o que sugere a necessidade de classificação específica para as respostas medidas em nutrição de eqüinos.

Coefficients of variation (CV) distribution for several variables in equine nutrition were obtained. The data are from theses and published scientific papers in equine nutrition. The CV were classified as low [CV£(m-1sd)]; medium [(m-1sd)(m+2sd)]. The Lilliefors test for all variables showed no discrepancy from normal distribution. The distributions obtained for coefficients of digestibility for cellulose and fibre in neutral and acid detergent, were close enough to the classification suggested in the literature. However, the distributions for coefficient of digestibility for gross energy and lignin, showed high discrepancies from this classification suggesting that trial precision should be evaluated according to the variable considered. There is a different distribution for coefficients of variation for each variable suggesting the need of specific classification for each characteristic in equine studies.

Dietary change in an intervention trial of wheat bran fiber and colorectal adenoma recurrence.

PURPOSE: The objectives of this study were to determine whether participants in the Wheat Bran Fiber (WBF) trial exhibited changes in diet over time, and whether these changes were differential by assigned treatment group. METHODS: The WBF trial was a randomized trial with participants assigned to one of two groups: a low-fiber (2.0 g/d) or high-fiber (13.5 g/d) wheat bran fiber cereal supplement. A total of 685 participants from both treatment groups completed the Arizona Food Frequency Questionnaire (AFFQ) at baseline, year one, and year three of the trial. Means were calculated for nutrient intake, change in nutrient intake, number of food group servings, and change in number of food group servings. RESULTS: For both treatment groups combined, significant increases were observed for most micronutrients and vitamins at years one and three, while fat intake significantly decreased. Participants from both groups significantly increased their consumption of cereals, breads, and crackers, but decreased the number of servings from the meat, poultry, and egg group, the fats group, and the salty snacks group. The only differential changes in intake between the treatment groups were for sugar and iron, which increased to a lesser extent among those assigned to the high-fiber treatment as compared with the low-fiber group. CONCLUSIONS: Although differential dietary intake was not appreciable in the WBF trial, participants exhibited longitudinal changes. Future intervention studies should carefully monitor dietary changes during the trial with multiple dietary assessment tools to assess potential secular and treatment-related diet changes.

Suppressive effect of viscous dietary fiber on elevations of uric acid in serum and urine induced by dietary RNA in rats is associated with strength of viscosity.

This study was performed to clarify how dietary fiber (DF) with different viscosities would be associated with dietary RNA metabolism. Male Wistar strain rats, four weeks old, were fed diets containing a 3% (w/w) yeast RNA and a 5% (w/w) viscous DF for five days. Viscosity of DF samples used, in order of strength, were xanthan gum (XG) > guar gum (GG) > locust bean gum (LBG) > karaya gum (KG) > pectin (PE) = arabic gum (AG) > CM-cellulose (CMC) = inulin (IN). The serum uric acid concentration in the viscous DF groups significantly decreased as compared with that in the cellulose (CL) group. The urinary excretions of uric acid and allantoin in the respective groups given AG, GG, IN, KG, PE, and XG were significantly suppressed as compared with those in the CL group. The fecal RNA excretion was markedly increased in the IN, KG, PE, and XG groups in comparison to the CL group. The DF with high viscosity significantly suppressed RNA digestion by RNase A and decreased uptakes of 14C-labeled adenosine and adenosine 5'-monophosphate (5'-AMP) in rat jejunum. The results reveal that the suppressive effect of DF on elevation of serum uric acid concentration induced by dietary RNA in rats is associated with the strength of DF viscosity. The mechanism by which this is accomplished is suggested to be attributed to the inhibitions of digestion for dietary RNA and/or absorption of the hydrolyzed compounds.

Healthy eating: something to chew over?

Most of us probably feel that we know enough about healthy eating and fibre in the diet; after all we have been advising people to eat more of it for years. But do we know all that we should? Alison Sullivan provides an update on the latest dietary recommendations.

Plausible mechanisms for the protectiveness of whole grains.

Dietary guidelines recommend the consumption of whole grains to prevent chronic diseases. Epidemiologic studies support the theory that whole grains are protective against cancer, especially gastrointestinal cancers such as gastric and colon can-cer, and cardiovascular disease. Components in whole grains that may be protective include compounds that affect the gut environment, such as dietary fiber, resistant starch, and oligosaccharides. Whole grains are also rich in compounds that function as antioxidants, such as trace minerals and phenolic compounds, and phytoestrogens, with potential hormonal effects. Other potential mechanisms whereby whole grains may protect against disease include binding of carcinogens and modulation of the glycemic response. Clearly, the range of protective substances in whole grains is impressive and advice to consume additional whole grains is justified. Further study is needed regarding the mechanisms behind this protection so that the most potent protective components of whole grains will be maintained when developing whole grains into acceptable food products for the public.

Effect of roughage type and concentrate supplementation on follicle numbers and in vitro fertilisation and development of oocytes recovered from beef heifers.

Increasing dietary energy tends to decrease the ovulatory response and produce fewer viable embryos following superovulation of beef cattle. Data in sheep indicate that high energy intake can decrease progesterone concentrations (P4), although effects in cattle are not as clear. The objectives were to evaluate the effects of roughage type and concentrate supplementation on P4 concentrations, follicle growth and subsequent oocyte fertilisation and embryo development in vitro. Forty-two beef heifers were allocated to 3 treatment groups: (i) silage ad libitum plus 6 kg concentrates (silage + conc.; n = 14); (ii) silage ad libitum (silage; n = 14) or (iii) hay ad libitum (hay; n = 14) for 40 days. Oestrus was synchronised using a controlled intravaginal progesterone releasing device (CIDR) for 7 days plus prostaglandin F2 alpha (15 mg luprostiol) administered 2 days before CIDR withdrawal. Ovaries were stimulated with 600 i.u. of follicle stimulating hormone (pFSH) administered in 6 equal doses at 12-h intervals, starting 12 days after CIDR withdrawal. Daily blood samples were collected from 3 days after CIDR insertion until CIDR withdrawal, and for another 3 days prior to pFSH, for P4 determination. Oocytes were recovered postmortem 12 h after the last pFSH injection, matured, fertilised and cultured in vitro. There was no overall effect of diet (P > 0.05) on P4 concentrations. The number of follicles grown in heifers on silage + conc (18.8 +/- 3.3), silage (23.5 +/- 3.4) or hay (18.1 +/- 2.6) were not affected by the dietary treatment (P > 0.05). The percentage of oocytes fertilised from heifers on hay (88%) was higher compared to oocytes from heifers on silage (79%; P < 0.05), but was not different (P > 0.05) compared to the proportion of oocytes from heifers on silage + conc. (86%). The percentage of fertilised oocytes that cleaved was higher from heifers on silage (94%; P < 0.01) compared with oocytes from heifers on hay (82%) or silage + conc. (86%). The proportion of embryos that developed to blastocyst was not different (P > 0.05) between groups of oocytes from heifers on silage + conc. (8%), silage (14%) or hay (15%). Heifers on silage produced numerically more blastocysts (silage: 19 from 14 heifers; silage + conc.: 8 from 14 heifers; hay: 12 from 14 heifers). These results suggest that dietary treatment used prior to oocyte recovery did not significantly influence the developmental competence of the oocytes in vitro.

Butyric acid from the diet: actions at the level of gene expression.

A number of components present in the diet, although nutritionally nonessential, have been discovered to have beneficial effects toward both general health and disease prevention/protection. One such nutrient, butyric acid, can be derived in large quantities from bacterial fementation of dietary fiber in the bowel and is also a component of bovine milk. In gut fermentation, the production of butyric acid defines its delivery point; thus, the synthesis and site of action of butyric acid are in close proximity and have frustrated the investigation of its activities in vivo. Recent research has, however, revealed a number of activities of butyric acid toward isolated cells. In particular, its ability to modify nuclear architecture and induce death by apoptosis in colon cancer cells is arousing great interest. Butyric acid changes the structure of chromatin through its effects on posttranslational modifications, key modifications being acetylation and phosphorylation of the nuclear histones. Butyric acid can also modify the differentiation state of cells, and in the case of cancerous colonic cells overcomes their resistance to normal programmed death. Thus, the activities of this fermentation product of dietary fiber may contribute substantially to the decreased incidence of bowel cancer that has been associated with fiber intake.

El germen desgrasado de maíz: materia prima potencial para la industria de alimentos / Defatted corn germ: potencial raw material for the food industry

Se presentan algunas características fisicoquímicas, nutricionales y funcionales del germen desgrasado de maíz (GDM) y su efecto sobre la respuesta glicémica. Se proponen aplicaciones como sustituto parcial del maíz y el trigo. El germen nativo tiene alto contenido de grasas (15-30 por ciento), proteínas (10-18 por ciento), carbohidratos (50-60 por ciento) y fibra dietética total (FDT,32-33 por ciento), principalmente insoluble. Del gérmen de trigo extraído por molienda se extrae aceite de maíz, y se generan grandes cantidades de de GDM en forma de torta desgrasada. Esta se procesa comercialmente obteniéndose una fracción fina (30 por ciento del GDM, de granulometría mayor de 70 mesh, 21 por ciento de FDT), y la gruesa (70 por ciento del GDM, menos de 70 mesh y 26 por ciento FDT). Ambas fracciones contienen minerales en mayor cantidad que la harina de trigo. El GDM es una materia prima potencial para la industria por ofrecer un suministrto contínuo todo el año, ser de bajo costo y tener valor nutricional superior al endospermo de maíz. Las propiedades funcionales permiten proponer el uso de la fracción fina como agente espesante y como sustituto parcial de la harina de maíz precocida, así como del trigo o en la elaboración de pan, galletas y pastas. Se ha estudiado la factibilidad de utilizarla para obtener derivados de almidones y proteínas. La fracción gruesa podría utilizarse para empanizar, elaborar pastas, galletas integrales y embutidos. El contenido de almidón y de FDT del GDM lo ubica como ingrediente energético rico en carbohidratos complejos, que provocan una respuesta glicémica moderada