So now we know what Prebiotics and Probiotics are, Dr Geoff looks at the health benefit claims:
There are many claims for the health benefits of regular consumption of probiotics and/or prebiotics. For example they are claimed to:
• Increase the availability of some vitamins and to reduce the bloating and diarrhoea that some people get because they cannot fully digest milk sugar (called lactose intolerance)
• Reduce the risk of gut infections and diarrhoea
• Reduce the risk of childhood eczema where taken by nursing mothers or added to bottle feeds
• Reduce the long term risk of bowel cancer
• Reduce the risk of vaginal thrush
• Reduce blood cholesterol
The evidence for the last three things on this list is either weak or the research is still at such an early stage that it is not yet possible to judge it properly. The evidence for the first three things on the list is more substantial. To test whether probiotics affect the risk of gut infections and diarrhoea is complicated by the fact there are several dozen different probiotic bacteria and several dozen different bacteria can cause diarrhoea. Overall their does seem to be fairly strong evidence that some probiotics can reduce the risk of some types of diarrhoea. The strongest evidence is that probiotics can reduce the risk of diarrhoea that commonly occurs after antibiotic treatment. There is conflicting evidence about their ability to reduce the risk of traveller’s or holiday diarrhoea but this may be because of the multiple causes and multiple probiotics problem mentioned earlier. There is some evidence that probiotics may have some benefits in treating and reducing the frequency of gut infections in babies and young children.
There are a small number of quite convincing studies that suggest that if particular probiotics are taken by nursing mothers or added to the feeds of bottle fed babies that it may reduce the chances of the baby developing allergic eczema by up to half. There is speculation but not much evidence as yet that this might also reduce the risk of other allergic conditions like asthma and hay fever in later years.
Lactic acid bacteria can reduce the symptoms of lactose intolerance even if they do not survive passing through the stomach because some of the lactose digesting enzyme may survive in the dead cells. Many non Europeans have some degree of lactose intolerance but these people can eat yoghurt and cheese without any problems because lactic acid bacteria have already digested the lactose.
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