6Probiotics
Section snippets
Gut microbiota—an unexplored ecosystem
The intestine's normal microbiota is as yet an unexplored organ of host defence. Although bacteria are distributed throughout the intestine, the major concentration of microbes and metabolic activity is found in the large intestine.1., 2., 3. The mouth harbours a complex microbiota consisting of facultative and strict anaerobes including streptococci, Bacteroides, lactobacilli and yeasts. The upper bowel is sparsely populated, and from the ileum on bacterial concentrations gradually increase,
What is the human intestinal ‘microbiota’?
For years, the microbial community in our intestines has been referred to as the ‘intestinal microflora’, or sometimes just ‘flora’. The term ‘microflora’ literally means ‘small plants’. However, bacteria, viruses, yeasts and protozoa are taxonomically markedly different from plants, and consequently, the use of the alternative term ‘microbiota’ (‘small life’) has been recommended.7
Moreover, the human intestinal microbiota is frequently discussed as if it were a defined entity. Accumulating
What is colonization—is manipulation of the microbiota possible?
According to the Oxford English Dictionary, to colonize is ‘to establish a settlement in a new country’. This is precisely what microbes do when they colonize the intestine. Whether colonization by a particular strain is of a shorter or longer duration is not obvious, but in most cases what is implied is a long-term presence in the intestine. For short-term ‘colonization’ use of the terms ‘transient colonization’ or ‘persistence’ is recommended.22
An obvious question, then, is whether any of the
Probiotics: the past, present and future
Probiotic bacteria, by definition, are living microbial food ingredients which have a beneficial effect on human health.3 The terminology originates from early studies assessing the effects of specific yogurt bacteria on the overall composition of the human intestinal microbiota. Probiotics were originally used to influence both animal and human health through intestinal microbiota alterations. At present, the specific live microbial food ingredients and their effects on human health are
Clinical prospects of gut microbiota research
The predisposition to infections is associated with immaturity and dysfunction of the gut defence barrier. In addition, many of the immunoregulatory aberrations favouring inflammatory response exert their major effects in early infancy, when the main load of new antigens is first encountered. The application of probiotics currently lies in reducing the risk of diseases associated with gut barrier dysfunction.4
The potential health effects of the normal gut microbiota need to be demonstrated by
Summary
The human gastrointestinal tract harbours a complex collection of microorganisms which form an individual microbiota typical for each person. Healthy microbiota is defined as the normal microbiota, which both preserves and promotes wellbeing and absence of disease, especially in the gastrointestinal tract. Correction of the properties of unbalanced indigenous microbiota forms the rationale of probiotic therapy. However, an important part of the beneficial effects of probiotics are related to
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