Advances in Probiotics

The bacteria of the intestine are many and varied in their properties. There sheer numbers in the colon, in particular, means that the bowel produces more enzymes and other compounds than the liver and can thus have a major impact on health. It is generally accepted that, ideally, the healthy GIT should contain only bacteria, though other organisms can be present. Although it is an over-simplification to catagorise bacteria as either "good" or "bad", it is difficult to avoid those descriptors. More correctly, the "goodness" or otherwise relates to the nett effect of the combination of all the micro-organisms present. However, it is true to say that most disorders of the intestine are caused by the microflora resident therein.
Medical conditions involving the microflora of Gastro-intestinal Tract may be divided into several groups:

• Firstly there are those where there is a preponderance of bacteria, protozoans or even, in some cases, yeasts with undesirable properties. These result in conditions such as Irritable Bowel Syndrome (IBS) diarrhoea and constipation (all of which are centred on the colon), gastric reflux and bloating (which are more centred on the small intestine) and Chronic Fatigue Syndrome (CFS), which may well relate to "imbalances" in either area and also to post-viral conditions. One research paper reported the presence of 200 times the normal level of Clostridia and E. coli in the colons of individuals with constipation. It seems that the production of neurotoxins, by these bacteria, paralyses the rythmic contractions (peristalsis) of the colon.
  
• A second group of conditions involves the auto-immune diseases and food sensitivities, both of which seem to be associated with the presence, in the small intestine, of bacteria that have the ability to open up "pores" or junctions in the intestinal wall, thereby permitting the translocation of both bacteria and large food molecules across into blood and lymph. This provokes an immediate response from the immune system which makes antibodies to the various bacterial components or food molecules in an attempt to throw off the invasion. In individuals who are genetically predisposed to a particular auto-immune disease, these antibodies then "recognise" similar structures in the body and attack those too. For example, it is known that the antibodies that attack human DNA in Systemic Lupus also cross-react with a piece of DNA (the lac 7 gene) of E. coli, suggesting that the latter is the trigger for the disease. In fact lupus sufferers (and those with rheumatoid arthritis) have been shown to have an overgrowth of E. coli from the colon, up into the small intestine.
  
• Another group of disorders is the asthma/hay fever/eczema group. In the small intestine there are myriad receptors called Peyer's patches and these are receptors that are connected into the immune system. Adhesion of the "wrong" bacteria to these receptors switches the immune system towards a more allergic response and reduces our resistance to infection. It is interesting that antibiotics increase the propensity for people to become allergic, presumably by killing off "good" bacteria and replacing them with bacteria that induce an increase in the production of compounds such as interleukin 4 which increase the allergic reaction. New research by U-M Medical School scientists Gary B. Huffnagle, Ph.D., and Mairi C. Noverr (Ph.D. 2002) suggests there’s a direct connection between microbial changes in the GI tract, caused by antibiotics, and how the immune system responds to common allergens in the lungs.
  “We all have a unique microbial fingerprint — a specific mix of bacteria and fungi living in our stomach and intestines,” says Huffnagle, an associate professor of internal medicine and of microbiology and immunology. “Antibiotics knock out bacteria in the gut, allowing fungi to increase temporarily until the bacteria grow back after the antibiotics are stopped. Our research indicates that these alterations in intestinal microflora can lead to changes in the entire immune system.” Read more at http://www.medicineatmichigan.org/magazine/2004/fall/huron/huron01.asp

• Cancer of the GIT can be caused by coliform bacteria converting bile into carcinogens. People who are chronically constipated increase their chances of getting bowel cancer because of increased contact time.