Probiotic yoghurts and drinks are marketed as aids to improve health and digestion. They contain high concentrations of digestion-aiding bacteria. However there is no evidence that they offer any real benefit unless you are unwell.
Within your bowels there are huge numbers of bacteria (about 100 trillion) that feed off the remnants of your last meal. They help digest your food, absorb nutrients and keep your immune system in tiptop shape. The types and amounts of different gut bacteria species are kept in a continuous balance. Occasionally, due to illness or a long course of antbiotics, the balance of gut bugs can be upset; some harmful types of gut bacteria can 'overgrow' and predominate, which can make you unwell. So for someone suffering diarrhoea due to antibiotics, probiotics, which contain high numbers of good bacteria, are proven as a useful treatment for replacing lost bacteria.
For pretty much everyone else, the balance of bacteria is likely to be fine, and adding extra from a probiotic will do nothing - though it won't do you any harm, either.
Dt Stuart Farrimond in the Wiltshire Times, 28 March 2014
