Good Bacteria, Bad Science

The purveyors of 'probiotic' products which 'top up your good bacteria' have now lurched into the kiddie market with a breakfast cereal that will work wonders on your children's guts.
These 'friendly bacteria' have escaped from their traditional home of 'live' yogurt and are now infesting products from drinks to handwash in a market worth possibly £135M a year.
I heard an expert on the ecology of the human gut say on the radio that the problem with the claims made for probiotic products is that the ecology of every human gut is unique. Not only that, the ecology of each individual's gut can be completely different every day. The implication of this is that for a top-up of good bacteria to be effective, the dose would have to be tailor-made for each individual person every 24 hours.
The mystery is how all this nonsense gets past Trading Standards, the Advertising Standards Authority and a raft of Government regulators.
These topics are trenchantly covered in The Guardian's Bad Science column every week, although he probably has to be more wary of m'learned friends than I do - if that's not tempting fate.