Prebiotic concept

More recently, the latter prebiotic concept was revised. The authors come to the definition that prebiotics have to be resistant until they are fermented by the intestinal (i.e., not only colonic) flora. The balanced stimulation of growth and/or activity of the health-promoting bacteria in the gastrointestinal tract have to be demonstrated finally by performing studies in the target group to produce sound scientific data (36). 

To increase the number of beneficial bacteria in the gut, large numbers of probiotic bacteria have to be consumed by means of capsules or by using food as vector. Incorporating suitable dietary polysaccharides or oligosaccharides to the capsules may be even more effective. The latter is referred to as the prebiotic concept. Arabinoxylan is another prebiotic compound commonly found in wheat and rye (Crittenden et al., 2002 Jaskari et al., 1998 Karppinen, 2003). 

Dewulf EM, Cani PD, Claus SP, et al. Insight into the prebiotic concept lessons from an exploratory, double blind intervention study with inulin-type fructans in obese women. Gut. 2013 62(8) 1112—1121. 

Human milk is a true prebiotic, and its neutral oligosaccharides are known as the main bifidus factor [404], which prevents digestive tract infections because it induces and improves the growth of good intestinal flora. The prebiotic concept was developed by Gibson and Roberfroid in 1995 [410]. According to their definition, a prebiotic effect is proven when bifidobacteria, lactobacilli, and other healthy bacteria are specifically stimulated and potentially harmful bacteria are depressed [411]. The concept of using prebiotics in infent formulas is related to three basic assumptions [412] ... 

Gibson, G.R. and Glenn, R. (2004) Fibre and effects on probiotics (the prebiotic concept). Clin Nutr Suppl 1, 25-31. Gibson, G.R., Probert, H.M., Loo, J.V., Rastall, R.A. and Roberfroid, M.B. (2004) Dietary modulation of the human colonic microbiota updating the concept of prebiotics. Nutr Res Rev 17, 259-275. 

Gibson, G. R. (2004). Fibre and effects on probiotics (the prebiotic concept). Clinical Nutrition Supplements, 7,25-31. 

GIBSON G R, ROBERFRoiD M B (1995) Dietary modulation of the human colonic microbiota introducing the concept of prebiotics. J Ante 125 1401-12. 

Concepts Spontaneous chemical reactions The use of thermodynamics to determine what reactions are possible in a particular prebiotic environment, including the ideas of chemical potential, equilibrium and extent of reaction... 

The conditions on Titan, both in the atmosphere and in the oceans, can be investigated using the kinetics and thermodynamics introduced in the modelling of the ISM and the prebiotic Earth, now tuned to the surface temperature and atmospheric temperature conditions on Titan. We have seen previously what happens to reaction rates in the ISM and the atmosphere using the Arrhenius equation but we have not yet extended the concepts of AG and thermodynamics to low temperatures. 

The recent developments and ideas in the field of prebiotic chemistry can be combined with the concepts noted here to produce what we regard as a research outline, rather than a detailed hypothesis, directed toward a coherent theory of the origin of complex self-contained, self-replicating chiral assemblies. In what follows we present one possible scenario that is consistent with our current knowledge of chiral induction and amplification and with the nature of early Earth as well as early life. It is exciting that this fundamental question can be formulated in a way that allows systematic experimental testing as we enter the next century. 

The next feature that I would like to discuss is the notion of selection that is central to the concept of evolution. That selection occurs even at the level of prebiotic conditions has been well demonstrated by Eigen and his group. In these experiments it was shown that several RNA sequences compete and of the many possibilities only a small fraction of... 

Figure 3. Some facts and open questions about the origin of life. The concept of an RN A world preceding present-day genetics based on DNA, RNAand protein, has been conceived by chemists and molecular biologists interested in problems of prebiotic chemistry and early biological evolution. Several pathways which are plausible under...

Heterogeneous photochemical processes are concerned with the effect of light on interacting molecules and solid surfaces. The concept of photoinduced surface chemistry is commonly used to integrate these processes. As cited earlier, they involve surface phenomena such as adsorption, diffusion, chemical reaction and desorption [3]. Experiments and theoretical calculations make clear that the photochemical behavior of an adsorbed molecule can be very different from that of a molecule in the gas or liquid phase [4]. Photochemical reactions of this type involve molecules and systems of quite different complexity, from species composed of a few atoms in the stratosphere to large chiral organic molecules that presumably were formed in prebiotic systems. 

One of the most talked-about dietary plans is the Garden of Eden concept (also called the Portfolio diet), which combines all the foods shown in scientific studies to lower levels of blood cholesterol. Key ingredients are soy products (fortified soy milk, tofu), phytosterol sources (banana, flaxseeds, strawberry seeds), prebiotic fiber (oatmeal, barley, psyllium, tofu, strawberries, banana), and nuts (almonds). 

Chemical evolution concerns the chemical processes that occurred on the ancient Earth about 4.5-3.5 million years ago. It is important to note that it preceded biological evolution that resulted in the formation of protocells. These forerunners of today s living cells were capable of self-reproduction at the expense of some protometabolism. After Oparin s ideas of the origin of life became widely known and especially after Stanley Miller reported his prebiotic soup experiments in 1953, the concept of chemical evolution became accepted. 

Roberfroid M. Functional food concept and its application to prebiotics. Dig Liver Dis 2002 ... 

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