Fiber and Prebiotics: Mechanisms and Health Benefits

Abstract

The health benefits of dietary fiber have long been appreciated. Higher intakes of dietary fiber are linked to less cardiovascular disease and fiber plays a role in gut health, with many effective laxatives actually isolated fiber sources. Higher intakes of fiber are linked to lower body weights. Only polysaccharides were included in dietary fiber originally, but more recent definitions have included oligosaccharides as dietary fiber, not based on their chemical measurement as dietary fiber by the accepted total dietary fiber (TDF) method, but on their physiological effects. Inulin, fructo-oligosaccharides, and other oligosaccharides are included as fiber in food labels in the US. Additionally, oligosaccharides are the best known “prebiotics”, “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-bring and health.” To date, all known and suspected prebiotics are carbohydrate compounds, primarily oligosaccharides, known to resist digestion in the human small intestine and reach the colon where they are fermented by the gut microflora. Studies have provided evidence that inulin and oligofructose (OF), lactulose, and resistant starch (RS) meet all aspects of the definition, including the stimulation of Bifidobacterium, a beneficial bacterial genus. Other isolated carbohydrates and carbohydrate-containing foods, including galactooligosaccharides (GOS), transgalactooligosaccharides (TOS), polydextrose, wheat dextrin, acacia gum, psyllium, banana, whole grain wheat, and whole grain corn also have prebiotic effects.

Modulation of the gut microbiota by prebiotic fibres and bacteriocins

“…Prebiotics are a subgroup of dietary fibres with resistance to gastric acidity and the digestive enzymes of mammals, and which confer a variety of health benefits [37,38]. The main characteristic of prebiotics is their selective stimulation of the growth and/or activity of intestinal bacteria associated with health and well-being [38].…”

“…Resistant starch fulfils the definition of a prebiotic [37,48]. It provides prebiotic-type fermentation in the colon and confers many metabolic benefits, such as increasing bile salt turnover and laxation, reducing the risk of gastrointestinal tract cancers, and lowering the postprandial glucose response and blood lipid levels [48,49].…”

Investigating cholesterol metabolism and ageing using a systems biology approach

“…There are a variety of mechanisms that dietary fibre could influence; for example, bile acid micelle formulation, fat excretion, intestinal motility, SCFA production and absorption of macronutrients (95)(96)(97) . Interestingly, diet may not only impact cholesterol metabolism directly, and may also interact with the gut microbiome (98) .…”

Efeito das farinhas de jatobá-do-cerrado (Hymenaea stigonocarpa Mart.) in natura e extrusada no metabolismo lipídico e parâmetros fermentativos em hamsters e resposta glicêmica em humanos após a extrusão

“…O amido resistente é um componente da fibra alimentar, caracterizado como um carboidrato dietético não digerível, que possui efeitos fisiológicos similares aos das fibras alimentares (FAO/WHO, 1998;SLAVIN, 2013), além disso, após o processamento por extrusão, há formação de amido resistente no produto final (SAJILATA et al, 2006), portanto, quantificouse, além da fibra alimentar, o amido resistente na farinha in natura e nas farinhas extrusadas.…”

“…Este resultado era esperado, uma vez que geralmente as fibras solúveis são quase totalmente fermentáveis e possuem maior viscosidade do que as insolúveis (WONG et al, 2006;SLAVIN, 2013), e as dietas dos grupos farinha in natura e extrusada continham 3,65 % e 5,47 % de fibra solúvel, respectivamente.…”