Michael Wilson, a professor of Microbiology at University College London, said the €230m+ UK probiotics industry lacked robust scientific backing while speaking at the Cheltenham Science Festival.
Professor Wilson did not write off the idea of topping up the system with “good bacteria” but countered it was based on “a lot of shaky understanding” and potentially problematic among those with certain ailments.
He acknowledged clinical trials had shown probiotic consumption could help people with disorders such as antibiotic-associated diarrhoea, but called for more robust testing.
Probiotics are best known for their ability to benefit gut health and boost the immune system but have shown potential in areas such as weight management and vaginosis.
“There are certain instances when probiotics are useful but the problem is there’s no regulation,” professor Wilson was quoted from his presentation in The Times.
“They are regarded as food supplements not medicinal products - anyone can get a suspension of bacteria and market it as a probiotic. With medicinal treatments, the pharmaceutical industry makes sure the things they produce are safe. There’s none of that with probiotics and the point is we just don’t know.
“It’s all well and good saying that certain bacteria are good for you, but we don’t know about all the other species in the gut and how they all interact. We are basing a lot of probiotic understanding on shaky ground. You need to know you are using appropriate strains for appropriate conditions in appropriate people and we just don’t know those things.”
Professor Wilson questioned the apparent logic of increasing probiotic counts in an ad hoc way, as some sections of the population, especially the sick, may react to this approach in an adverse way.
“No bacterium is totally innocuous,” he said. “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.”
“The fact is we know so little about microbiota,” he concluded.