Beneficial bacteria are normally found in the gut in adults but the stock runs out due to poor nutrition, stress and other external influences. People resort to probiotic items to balance this deficiency of beneficial bacteria.
Prof Gibson, who led the research, said, "Half the products on sale don't contain the bacteria they say on the label. As a rule of thumb, you can trust the big manufacturers. Their quality control is very good. It would be disastrous for Nestlé, Danone or Yakult to have these other organisms in their products. On the other hand, there are a lot of manufacturers - many of which sell products on the web - who are unheard of and these are the ones to worry about. Half of the products you can buy have got the wrong bacteria in them, the wrong amount, or are completely sterile. There's no legislation to protect you against this at present."
The professor also warned against potentially harmful organism called clostridia that is present in a product called Acidophilus, which incites spores that are defiant to the effects of antibiotics. Products that are safe for consumption include Activia, Immunitas, Digestivas, Yakult, Actimel, Vitality and the tablet Multibionta.