Metabolite Production during in Vitro Colonic Fermentation of Dietary Fiber: Analysis and Comparison of Two European Diets

Abstract

Metabolite production and antioxidant released during colonic fermentation of naturally occurring dietary fiber (DF) from two European diets (Mediterranean and Scandinavian) were determined. With this aim, DF and associated components were isolated from both whole diets, as well as from cereals and fruits and vegetables comprising the diets. DF was used as substrate for colonic fermentation in a dynamic in vitro model of the colon, samples were collected, and fermentation metabolites were analyzed. Statistical differences between samples were observed in the concentrations of short-chain fatty acids and ammonia and in the ratio acetate/propionate/butyrate. Whole grain cereal DF generated a larger amount of propionate than refined flour cereal DF. Fruit and vegetable DF generated higher amounts of butyrate than cereal DF. Most antioxidant compounds were released from DF during in vitro colonic fermentation. It is concluded that different sources of DF may play a specific role in health maintenance mediated by metabolites produced during colonic fermentation.

Synergic effect of exogenous microorganism combination on propionic and butyric acid formation during in vitro colonic fermentation of maize resistant starch

“…A different result is also found in other reported researches. Tabernero et al [25] investigated in vitro colonic fermentation of dietary fibers from two European diets, and found butyric acid to be the least produced. Williams et al [26] fermented arabinoxylan or b-glucan with fecal inoculum from porcine for 48 h, and found propionic or butyric acid to be less or the least produced.…”

Approaches that ascertain the role of dietary compounds in colonic cancer cells

“…The physiological properties of diet-derived mixtures could be analyzed with in vitro models of the human GI tract, and one such model has been developed by TNO in the Netherlands [55] . This system closely mimics the physiological conditions in the GI tract, as established in numerous validation studies [32,[56][57][58][59][60][61][62][63][64][65][66][67] . The GI system is composed of two separate models: TIM-1 that simulates the stomach and the small intestine (not further discussed here), and TIM-2 that simulates the colon [68] and contains compartments with a high density, metabolically active microbiota of human origin.…”

“…The technology also allows for controlled analyses on the colonic outputs from various diets. Thus, entire meals representative of different types of diet can be "fed" to the GI model [60] and the resulting real-time fermented samples from the TIM-2 compartments can be tested on neoplastic and normal colonic cells in vitro [32] . Although fecal water from human subjects could be used for similar studies, there are several problems associated with this approach: inter-individual differences in metabolic rates and colonic microbiota, noncompliance with diet, preferential absorption of some compounds by the colonocytes, and the impossibility of acquiring samples from different locations of the human GI tract (e.g., pre-colon, proximal colon).…”

Could cheese be the missing piece in the French paradox puzzle?

“…However, besides red wine and its major constituent resveratrol, which seem to confer cardioprotective effects on wine drinkers [4], multiple other factors seem to be implemented in the French paradox. These include smaller portion size, lower number of eating occasions, regular gardening and exercise and higher intake of fruit and vegetables rich in flavonoids, phytosterols and dietary fiber [5][6][7][8]. Although a single causative factor explaining the occurrence of ''French paradox'' is unlikely ever to be found, the identification of contributory factors to reduced cardiovascular mortality in France would seem to be extremely important.…”