Consuming probiotic supplements is of no benefit to healthy people and can, infact, harm a person with compromised immune systems, warns a leading microbiologist.
According to Michael Wilson, Professor of Microbiology at University College London, there were some cases when topping up on "good bacteria" could help recovery from illness, but understanding of the supplements is "shaky".
"There are certain instances when probiotics are useful but the problem is there's no regulation," The Telegraph quoted Wilson, as saying.
"They are regarded as food supplements not medicinal products - anyone can get a suspension of bacteria and market it as a probiotic," said Wilson, speaking at the Cheltenham Science Festival.
"With medicinal treatments, the pharmaceutical industry makes sure the things they produce are safe," he added.
Prof Wilson believes increasing the bacterial load in people with compromised immune systems could lead to health problems.
"No bacterium is totally innocuous. If you are healthy there is probably no harm in taking probiotics, but there is also no benefit. But to increase the bacterial burden if you are immuno-compromised is asking for trouble," he said.