Miracle Bug
Fancy 'probiotic' yoghurt drinks are they good for you?
Probiotics are one of the most over-hyped health products of recent years.
Until now doctors have been sceptical about these yoghurts, drinks and pills -
partly because the evidence for them hasn't been convincing, but also because
it's not clear what the different strains of these 'good' bacteria actually do.
However, new research shows that not only are probiotics useful, but they could
even act as effective medicines - and help you control your weight.
Probiotics are the 'good' strains of gut bacteria which play an important
role in digestive health and the immune system. The problem, as many a
nutritionist likes to point out, is that these good bacteria can be killed off
by poor diet and antibiotics.
Now, scientists have been able to pinpoint precisely what effects particular
types of bacteria have. For instance, they have found that some influence the
ways fats and nutrients are absorbed.
More importantly, this new understanding is helping them develop ways to
adapt probiotics more precisely. It seems they could actually replace certain
drugs such as antibiotics and even provide new treatments for other conditions
such as asthma - and without side effects.
Last month, for instance, researchers from University College Cork reported
that two probiotics specially prepared in their lab were as effective as the
best available antibiotics in fighting off various infections in animals.
Lead scientist Dr Colin Hill explains that each works in different ways.
'We've got one that protects mice from an infection called listeriosis that
causes vomiting and nausea and can affect pregnant women. The probiotic works by
producing a type of small molecule known as a peptide that specifically kills
the listeria bacteria.'
The other probiotic strain, rather than directly destroying the harmful
bacteria, stimulates the gut to produce a strong immune response that does the
job instead.
The Cork researchers have also been experimenting with genetically modifying
a probiotic to carry a gene that allows it to target the harmful gut bacteria
Clostridium difficile, which kills thousands of elderly patients in hospital
every year.
'The carrier probiotic is a hardy strain that survives the passage through
the acid in the stomach very well,' says Dr Hill.
But targeted probiotics don't only work by killing off dangerous pathogens;
they can also prevent infections simply by preventing invading bacteria from
establishing themselves.
Recently, a team from University Hospital in Lund, Sweden, found that a
certain type of bacteria was as effective as an antiseptic in preventing
patients on ventilators from developing pneumonia.
What's more, the probiotics didn't cause the irritation and allergic reaction
that can come with an antiseptic.
Another area of probiotic use that has been attracting a lot of attention is
the effect they can have on your risk of putting on weight.
This makes sense because we absorb nutrients and calories in the gut, and
bacteria are intimately involved in that process. A number of researchers have
found that just taking the kind of preparations you can buy over the counter can
affect weight gain.
Finnish researchers recently reported that children who had larger amounts of
a strain called bifidobacteria when they were infants were more likely to be a
normal weight at the age of seven than children who had low levels of this
probiotic.
Then last week, at the European Congress on Obesity, the same team described
how women who took a supplement of two widely used probiotics through their
pregnancy in a controlled trial had less belly fat.
'This is the sort of fat that is associated with raised risk of diabetes and
heart disease,' said lead researcher nutritionist Kirsi Laitinen.
'Only 25 per cent of the women who got the probiotics plus dietary
counselling developed belly fat, compared to 43 per cent who received only the
dietary advice.'
The big question, of course, is how do probiotics have this effect on weight
gain?
The interaction of two bacteria seems to be the cause, according to a report
published last year in the journal Proceedings Of The National Academy Of
Science.
This revealed that the two bacteria which aren't found in people of normal
weight are present in those who are obese, and meant they absorbed more calories
from their food and stored more fat. Scientists are looking at ways of using
probiotics to modify the action of these fat-inducing bacteria.
Some probiotics can also have a negative effect, studies have shown.
In a project under way at Imperial College, London, researchers have been
investigating what effects just two of the hundreds of probiotics can have.
They found a huge range, such as how much cholesterol you have in your blood
and how well you fight infection.
But they've also found that some can be harmful. For example, while both of
the probiotics seem to help fight off the hospital superbug infection MRSA, the
most effective one also boosted the amount of E.coli - another dangerous
bacterium.
We should be able to use probiotics much more effectively once scientists
have finished a huge project now under way to identify all the different strains
living in our guts.
As top microbial researcher Professor Glen Gibson, of Reading University,
explains: 'We each have a unique human genetic fingerprint, but we also each
have a bacterial genetic fingerprint.'
He believes that finding out how these two sets of genes affect each other
will 'ultimately create a powerful new tool to pinpoint your personal health
risks and strengths'.
When all this research starts coming together, we will have a much more
detailed picture of how bacteria affect us and how we use them much more
precisely. We will be able to manipulate directly such things as our weight or
levels of fats and cholesterol in blood, as well as gut disorders and
infections.'
So while we are waiting for a new world of probiotics treatments to arrive,
what should we do?
We know that all sorts of things, such as antibiotics, diet and a weakened
immune system, can affect your beneficial gut bacteria,' says Professor
Gibson.
'And there is quite good evidence that, in healthy people, taking probiotics
can have various good effects, such as reducing the number of colds you get and
making it less likely you will have to have a day off work.
'So, if you are taking them at home, go for the familiar ones such as
lactobacillus and bifidobacterium, and make sure you get a brand that has at
least ten million bacteria per dose.'
So how can you make sure you are taking the right probiotics?
Here, we offer a guide:
- PROBIOTIC drinks and supplements are better than yoghurts as they contain
more friendly bacteria. But beware, some probiotic drinks are full of sugar.
More than 10g per 100g is considered high, so if you're diabetic or watching
your sugar intake, it's best to opt for a pill.
- LOOK for products containing both bifidobacteria and lactobacilli. They
don't play vastly different roles, but taken together they promise a better
bacterial hit.
Also check the label for prebiotics (edible fibres that help pre-existing
healthy gut flora to flourish); you'll need at least 5g prebiotics a day for a
real effect.
Prebiotics will be listed on the label as inulin or fructo-oligosaccharides.
If you're prone to diarrhoea or bloating, don't take prebiotic-laden
formulations without professional advice.
- MAKE sure the probiotic dose is high enough; you need at least ten million
live micro- organisms. Reputable probiotics will list the strain and number of
live microorganisms on the label - most of the drinks available in the
supermarket will have around this amount. Always consume refrigerated drinks
before the expiry date as they're likely to become ineffective.
- YOU need to take your probiotics every day to see the benefit - it's no good
leaving days in between having them, whether you're taking them short term or
for longer.
- DO YOUR research. Probiotics are food supplements, so they can't make
medical claims.
But you can search for information on specific strains on scientific
publishing sites such as www.pubmed.com. -
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