According to experts as many as half of all probiotic health drinks do not contain the healthy bacteria they claim on the label.
A panel of British microbiologists from British warned yesterday that though established brands such as Yakult, Danone, Müller or Nestlé do not try to mislead consumers, as many as 25 products many of which are sold on the web - either do not contain the right bacteria, or contain it in too small quantities.
The experts say consumers should be suspicious unless the probiotic drinks and capsules state they contain lactobacilli or bifidobacterium and stipulate a minimum of 10 million bacteria per bottle.
The panel comprising Glenn Gibson, professor of food microbiology at the University of Reading, Sandra McFarlane, a microbiologist at Dundee University, and Christine Edwards, head of human nutrition at Glasgow University, say consumers need to be aware of these facts.
It seems the "healthy bacteria" account for 10-15% of the bacteria in the gut in adults, but become depleted through poor diets containing too much fatty, low fibre, preservative-laden food, environmental factors, antibiotics and stress.
Probiotic products attempt to redress the balance, and consumers are increasingly buying into the idea of replenishing their supplies of "healthy bacteria" with probiotic yoghurt drinks and yoghurts; a market said to be worth £307m a year.
Probiotics are thought to aid digestion and cut the risk of stomach upsets and some research suggests they help prevent bowel conditions such as ulcerative colitis, protect children against allergies, and may even reduce the risk of colon cancer.