Taking a course of antibiotics could harm the beneficial bacteria living inside us. So should we be taking probiotics after we finish them? The answer may not be so simple.
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| Taking probiotics when your
gut health is weak may not be a good idea (Credit: Getty Images) |
Probiotics have been touted as a
treatment for a huge range of conditions, from obesity to mental health
problems. One of their popular uses is to replenish the gut microbiome after a course of antibiotics. The logic is – antibiotics wipe out your gut bacteria along with the
harmful bacteria that might be causing your infection, so a probiotic can help
to restore order to your intestines.
But while it might sound like sense, there is scant solid evidence
suggesting probiotics actually work if taken this way. Researchers have found that taking probiotics after antibiotics in fact delays
gut health recovery.
Part of the problem when trying to figure out whether or not probiotics
work is because different people can mean a variety of things with the term ‘probiotic’. To a scientist, it might be seen as a living
culture of microorganisms that typically live in the healthy human gut. But the
powdery substance blister packs on supermarket shelves can bear little
resemblance to that definition.
Even when researchers use viable, living bacterial
strains in their research, the cocktail varies
from one lab to another making it tricky to compare.
[…] A particular concern is a lack of research on the
safety of taking
probiotics. While they are generally assumed to be safe in healthy people, there have
been worrying case
reports of probiotics causing problems – such as fungus spreading into the blood
– among more vulnerable patients.
A recent study by
scientists at the
Weizmann Institute of Science in Israel found that even among healthy people, taking probiotics after antibiotics was not
harmless. In fact, they hampered
the very recovery processes that they are commonly thought to improve.
The researchers,
led by Eran Elinav, gave 21 people a course of broad-spectrum antibiotics for one week. After
this, they had a colonoscopy and an upper-gastrointestinal endoscopy to investigate the state of their microbiome
throughout the gut.
[…] The volunteers were divided into three groups. The
first was a wait-and-see group, with no intervention after the antibiotics. The
second group was given a common probiotic for a month. The third was given
perhaps the least savoury option: a faecal transplant. This group had a small
sample of their own stool – taken before the antibiotic treatment – returned to
their colon once the treatment was over.
The surprising
finding was that the group who received the probiotic had the poorest response in terms of their microbiome. They were the
slowest group to return to a healthy gut. Even at the end of the study – after five months of monitoring – this
group had not yet reached their pre-antibiotic gut health.
“We have found a
potentially alarming adverse effect of probiotics,” says Elinav.
The good news,
incidentally, is that the group who received a faecal transplant did very well indeed. Within days, this group completely reconstituted their original
microbiome.
“So many people
are taking antibiotics all over the world,” says Elinav. “We can aim to better
understand this potentially
very important adverse effect that we didn’t realise existed.”
And the evidence
is mounting that taking
probiotics when gut health is weak is not
such a good idea. Another recent study has
found that probiotics don’t do any good for young children
admitted to hospital for gastroenteritis. In a randomised controlled trial in the US, 886 children with
gastroenteritis aged three months to four years were given either a five-day
course of probiotics or a placebo.
The rate of
continued moderate to severe gastroenteritis within two weeks was slightly
higher (26.1%) in the probiotic group than in the placebo group (24.7%). And
there was no difference between the two groups in terms of the duration of
diarrhoea or vomiting.
Despite evidence such as this, the demand
for probiotics is large and growing. In 2017, the market for probiotics was more than $1.8bn, and it is predicted to reach $66bn by 2024.
“Given the very heavy involvement of the industry,
clear conclusions as to whether probiotics are
truly helpful to humans remain to be proven,” says Elinav. “This is the
reason why regulatory authorities such as the US’s Food and Drug Administration
and European regulators have yet to approve a
probiotic for clinical use.”
But that is not to
write off probiotics completely. The problem with them may not be with the
probiotics themselves, but the way we are using them. Often probiotics
are bought off the shelf –
consumers may not know exactly what they are getting, or even whether the
culture they are buying is still alive. […]
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