TV, radio and newspapers are awash with adverts for ‘probiotic’ yoghurt products.
It’s been assumed that anything that boosts ‘good’ bacteria in the stomach and gut is beneficial.
But now scientists at the European Food Safety Agency (EFSA) have announced that there is little evidence to support the health benefits of probiotic products.
And only a couple of weeks ago, the Advertising Standards Authority refused to allow a new advert suggesting that children who consume probiotic yoghurts will boost their natural defence mechanisms.
The claim that probiotics are giving health benefits are being challenged and Huddersfield University scientists are leading the charge.
For two decades, the university has been at the forefront of research into the human body’s complex relationship with its bacteria.
This research got a huge boost a decade ago with a £1m EU grant and university scientists comprise one of the few UK teams to study the molecular structure of the bacteria in the stomach and gut.
“We are building a picture of the bacteria that communicate with the immune system and the chemical messengers they use,” said Dr Andy Laws, a reader in chemistry at the university’s department of chemistry and biology.
“Research is now putting more emphasis on ‘prebiotics’, (non-digestible food fibres and complex sugars) on which bacteria feed.”
There are between 4,000 and 500 different kinds of bacteria in the gut, some good and some bad.
You can distinguish and to an extent ‘sculpt’ the prebiotics to help the good bacteria thrive and deprive the bad bacteria of nourishment.
This, rather than the indiscriminate bombardment of the gut with probiotics, might be the way forward, says Dr Laws.
“The manufacturers of probiotics have met problems in which their products have had an adverse effect on the stomach, creating excess wind,” he said.
“So should we rush to consume probiotic yoghurts? The answer is not clear.
“If you have a good diet then your gut bacteria should be strong enough to supply the immune response needed to keep you healthy.
“There is evidence in the scientific literature to suggest that the consumption of probiotic drinks can be advantageous when the normal gut flora has been damaged, such as after antibiotic treatment.”
“At the same time, there are a limited number of reports that the consumption of too many probiotic strains – particularly by people who have serious medical conditions such as pancreatitis – can have negative effects.
“This is an area of research which we urgently need to develop. We need to know how the communication between the normal gut flora and the immune system works.”
One of the most common causes of a breakdown in this communication is after treatment with antibiotics.
Often elderly patients who have bacterial infections are given broad spectrum antibiotics that help them tackle infections.
However, these antibiotics also kill a significant proportion of the normal healthy gut flora.
This gives resistant strains of bad bacteria, notably C. difficile, the opportunity to colonise the gut with the consequence that patients experience so called ‘antibiotic’ induced diarrhoea.
There are also a number of severe diseases where there is believed to be the result of poor communication between the bacteria and the immune system.
Crohn’s disease and inflammatory bowel disease are the most notable here.
We often think of bacteria as harmful organisms, but while many do cause disease, some are beneficial to the body.
Since the majority of these bacteria are in the gut, the gut can be viewed as the body’s largest immune organ with the biggest responsibility for fending off harmful organisms known as pathogens.
Good bacteria also plays another important role, breaking down food we eat to provide a source of energy essential for the cells that line the intestines.
Yet another benefit is that good bacteria helps to make vitamins needed by the body and keep the digestive system working as it should.
Probiotics like lactobacilli plantarum and bifidobacteria, which are favoured by the therapeutic yoghurt makers, are present naturally in fruit and vegetables, but you have to eat massive amounts each day for the bacteria to have an effect.
And, indeed, if you choose to take Actimel, Muller or other products, the benefits will only be felt if you take them regularly.
One live yoghurt just isn’t enough to repopulate your intestines with healthy bacteria.
Dr Trisha Mcnair, the BBC’s health adviser, said: “It may be more effective to take prebiotics that boost growth of the good bacteria you already have in your gut, rather than take supplements of live bacteria that may be destroyed by the acidity of the stomach as soon as you swallow them.”