Peter
Cartwright investigates whether probiotics have any benefit, or whether
they are just another health fad.
Probiotics
are appearing in increasing numbers. In the supermarket there are little
bottles of milk drinks containing ‘friendly bacteria’, and there is a
growing range of bio-yoghurts and similar fermented products. Health food
stores and vitamin/mineral suppliers stock capsules and powders with names
such as ‘acidophilus’.
But
what exactly is a probiotic?
Probiotics
are products containing special types of microbes (live microscopic
creatures) which help to create a better mixture among the bacteria living
in the human intestine. Each of us has billions upon billions of bacteria
living in the lower gut. These resident bacteria are commonly known as the
microflora, and some of these bacteria are more desirable than others. By
consuming probiotics, the idea is to increase the numbers of the better
bacteria.
We gain
our microflora in the first few days of birth, and the mixture becomes
fully developed from the time of weaning. One of the benefits of the
microflora is that they prevent harmful microbes (pathogenic bacteria,
viruses, fungi and parasites) from growing in the intestine and causing
disease.
But the
protective process sometimes called “competitive exclusion” does not
always work. If you eat food that is seriously contaminated by harmful
microbes, they may be so great in number that they become established
despite the opposition of the microflora, leading to infectious diarrhoea.
Sometimes,
antibiotics are prescribed to counter an infection, but in addition to
attacking harmful bacteria, the antibiotics also kill the protective
bacteria. The resulting “vacuum” in the lower intestines can make it
easier for other harmful microbes to get established, leading to what is
known as “antibiotic-associated diarrhoea”.
Certain
long-term conditions have altered mixtures of bacteria in the microflora.
People with Crohn’s disease and ulcerative colitis (UC) have a different
mixture from people without these illnesses. There are more of the types
that can be harmful and fewer of the beneficial types (e.g., lactobacilli
and bifidobacteria).
Is
there any evidence that taking probiotics can lead to improvements in
health?
Over
the last 10 years there has been a growing amount of scientific evidence
that shows that probiotics can:
If you
have Crohn’s disease and an ileostomy or a colostomy, probiotics may be
able to reduce the severity of your continuing inflammation.
There
is a problem with probiotics, however. They cannot be prescribed by
doctors as there are not classified as drugs.
Instead,
they are food or food supplements. While this means that they can be
purchased over the counter, it also means that the products are not
allowed to claim that they treat or prevent disease.
It can
therefore be difficult to know how to choose a probiotic that is likely to
be effective in altering the microflora mixture and leading to better
health.
Factors
you should look for in a good product include:
