Investigating the effect of ‘probiotic’ yoghurt drinks on intestinal health - page 1
Keywords: probiotic stomach conditions bacteria dillution and plating series experiment bifidobacteria
By xbryonyx on 13/02/2007
Level: A Level (Year 12) / AS Level
Page Number: 1 of 3 pages: 1 2 3
Investigating the effect of ‘probiotic’ yoghurt drinks on intestinal health
Introduction
In this investigation I aim to explore the claim that ‘friendly’ bacteria in yoghurt drinks described as ‘Probiotic’, such as Actimel and Yakult, have a positive effect on health. Questions are raised as to whether ‘Bifidus Digestivum’ can survive the passage through the stomach and intestines and whether, if they do, they have a positive effect or, in fact, claimed improvements are coincidental or psychosomatic.
‘Bifidus Digestivum’ is actually a trade name of the Bifidobacterium animalis strain number DN 173 010, registered by the Danone company (1), a type of bifidobacteria found in the intestines of humans and animals. They are saccharolytic organisms that produce acetic and lactic acid without the generation of carbon dioxide, except during the degredation of gluconate.The population of these bacteria in the colon appears to be relatively stable until advanced age when it appears to decline.(2) There is a huge range of explanations given for this decline from inactivity to stress to antibiotics but, however explained, it is believed that ‘topping up’ this bacteria will lead to fewer stress related illnesses etc hence the wide use of ‘probiotic’ yoghurt drinks. (3)
There are, however, problems with the reasoning and claims made by companies such as Danone, the most prominent being speculation over whether the bacteria could survive the gastric transit. The wall of the stomach itself is made up of four layers: the mucous, submucous, muscular, and peritoneal layers. The mucous and submucous layers are made up of ridges called rugae. Within the ridges are gastric glands made up of mucous cells, parietal cells, chief cells, and G-cells. Each of these cells secretes a chemical that aids in the process of digestion.The stomach secretes 2–3 quarts (liters) of gastric juices every day. There are several types of specialized cells in the stomach that secrete gastric juices.Exocrine glands are located in the fundus and body of the stomach. These contain parietal cells that secrete hydrochloric acid (HCl), which makes the stomach strongly acidic, with a pH of about 2 or 3. This is an optimal pH for the action of pepsin enzyme that is responsible for the initial breakdown of protein molecules into smaller polypeptides. Hydrochloric acid is responsible for transforming the inactive pepsinogen into active pepsin. The hydrochloric acid in the chyme also stimulates the production of pancreatic and biliary secretions that further stimulate digestion. The
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