Free Health Dissertations - Scientifically, The Benefits Of Probiotics Have Been Studied For At Least A
Scientifically, the benefits of probiotics have been studied for at least a century. As early as 1908, Elie Metchnikoff’s microbiological studies of the longevity of Bulgarian peasants, who had a diet rich in yoghurt, demonstrated the importance of microbial homeostasis, or bacterial balance, in the intestinal system. In what he termed the autointoxication effect, Metchnikoff theorised that harmful bacteria in the colon were adversely affecting the human host and that the condition could be reversed by ingesting soured milk. (Duggan et al. 2002; Gibson and Fuller 2000; Trankina 2002) Most studies on prebiotics have been conducted in Japan, dating to approximately 1978, although the term prebiotic was not established until the mid-1990s (Gibson and Fuller 2000; Gibson and Roberfroid 1995, cited in Gibson and Fuller 2000).
The Intestinal Environment
Adult humans have approximately one kilogram of live bugs residing inside their digestive tracts (Johnson 2004). These bugs represent over 400 diverse species which help to break down food substances thereby releasing nutrients (Gill and Guarner 2004; Johnson 2004). Colonisation of the human intestinal system by these bacteria begins at birth, maturing at about two years of age and maintaining at fairly stable levels through life (Gill and Guarner 2004). In terms of numbers, there are ten times as many bacteria in the intestinal tract as there are eukaryotic cells in the human body (Holzapfel et al. 1998) and that there are many more bacteria in the colon than in the stomach (Gill and Guarner 2004).
Most bacteria present in the intestine, such as Bifidobacteria and Lactobacilli, are either beneficial or benign (Gill and Guarner 2004; Reid et al. 2003; Trankina 2002). But some bacteria, such as Clostridia, may cause illness. Under normal conditions there is a balance between healthful and harmful bacteria but, when the balance is disturbed, the body is susceptible to diseases of an acute nature such as gastroenteritis and those of a chronic nature such as colon cancer. (Gibson and Fuller 2000; Gill and Guarner 2004)
Definitions of Probiotics and Prebiotics
Probiotics is derived from the Greek term for life (Trankina 2002; Reid et al. 2003). Definitions of probiotics have changed over time, but generally contain the following common elements: live microorganisms that, when ingested in sufficient quantities, offer health benefits.
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