Probiotics: If you do not just make them poop, they may eat away at you

There is a hot cloud of hype and hope around probiotics – and researchers have long tried to clarify what sandblasting products could (and usually can not) do. Now, a new series of studies offers a thorough check on funky claims, tearing current probiotics as probably ineffective for improving health and potentially even causing harm.

In both studies, both published this week in the journal CellIsraeli researchers report that the bacteria taken in supplements, aka probiotics, often have a low impact on the bowels of healthy people and, at worst, can displace indigenous populations of microbes.

In the first study, researchers found that healthy microbial populations in people's plumbing tended to flush out newcomers. Thus, microbial intruders of supplements have little impact on resident microbiomes – and, by extension, on the health of consumers – and are largely abandoned.

But the researchers found in the second study that probiotic strains can more easily take root in the gut if a person takes a high dose of antibiotics that repels their beneficial bacteria. This finding could suggest that live supplements could help rejuvenate the inhabitants of the intestine after an antibiotic attack, as probiotic manufacturers would surely like to claim. But in fact, probiotics did Stronger The researchers found that the native community of healthy intestines could recover. People who took probiotic supplements to rally their microbiome after antibiotic therapy did not find their community healthy for five months. People who took nothing after their antibiotics did it.

The nauseating results are not shocking given the disappointing and inconclusive data on probiotics. A 2016 study of randomized controlled trials concluded that probiotics had virtually no effect on the overall mix of microbes in people's poop. While other studies have found microbial changes in probiotics, there is still little data on what these changes could mean in terms of health and what our microbiomes actually do for us. And previous studies specifically dealing with the use of probiotics after antibiotics also revealed that the supplements were ineffective. For example, probiotics could not stop antibiotic-induced diarrhea or counteract the more serious intestinal invader associated with antibiotics, Clostridium difficile.

Until now, such discoveries have not deterred consumers from spending money on probiotics in the hope of better intestinal health. Probiotics are a steadily growing market, with 3.9 million adults in the US using probiotics or prebiotics. They are among the most commonly used dietary supplements.

And the idea probiotics are still not stupid. Communities of microbes that proliferate in our intestines do all kinds of useful things: they can alter our immune response, influence our hormones, protect us from infectious germs, help us digest and process food, and keep things well and regularly. . The optimization and stabilization of these communities could have a lot of benefits and help to counteract diseases. The problem is that we do not know enough about our complex and highly variable microbiomes to handle them effectively, despite what the probiotic manufacturers will try to tell you.

The good news is that the new series of studies contains useful tips for moving forward.

flushed

For the first study, researchers at the Weizmann Institute of Science in Israel turned to a commercially available probiotic product that included 11 strains of bacteria. These insects are commonly used in products and believed by marketers and some consumers to improve health. Their inventory includes: Lactobacillus acidophilus, L. casei, L. casei sbsp. paracasei, L. plantarum, L. rhamnosus, Bifidobacterium longum, B. bifidum, B. breve, B. longum sbsp. infantis, Lactococcus lactis and Streptococcus thermophilus. The researchers independently confirmed that these bacteria were alive and coming into play in the probiotic mix.

Fifteen healthy adults accepted that their bowels and stools were detected before starting the test. They performed colonoscopies (to sample microbes in the lower gastrointestinal tract) and endoscopies (to sample microbes in the upper gastrointestinal tract). Next, 10 volunteers took a probiotic course twice a day for four weeks and the other five received a placebo. They all took their excrement and underwent colonoscopies and endoscopies three weeks after the treatments.

The researchers found a lot of microbial variability in individuals before and after treatments. But for the most part, probiotics seemed to have little effect. Those who took probiotics clearly expelled them while they were taking them. The five who received the placebo did not – as expected.

Six of the 10 people in the probiotic group were termed "permissive" because some probiotic strains appeared to remain in their lower gastrointestinal tract at low levels after the four-week treatment. The other four were dubbed "resistant" because the probiotic strains appeared to be emptying completely. Importantly, these designations were based solely on direct intestinal sounding – not on what researchers could see in the stool samples. These deposits were almost useless for knowing which probiotics colonized the intestine.

When the researchers took a closer look at intestinal data, they noted that permissive people tended to have lower levels of probiotic strains in their intestines. before the treatment that the crowd resistant. Thus, probiotic strains may have been easier to find a niche in the permissive group due to less competition from resident microbes.

Overall, the researchers drew two main conclusions from the study. The first is that poo samples are not very useful for collecting information about the proliferation of probiotic bacteria in the intestines. This is rather remarkable, as many studies on the microbiome rely on faecal samples to assess residents of the microbiome. The second thing to remember is that the microbes already in our bowels seem to indicate which probiotic strains have a chance to colonize. Thus, effective probiotics may need to be custom designed for individual microbiomes.

Microbial chaos

Of course, this study was all about people in good health. Many consumers turn to probiotics when they are not in good health. In the second study, researchers sought to examine the effects of probiotics on microbiomes that were known to

For this, 21 healthy adults were treated with antibiotics for seven days, which allowed their microbiomes to be recovered. This kills resident microbes indiscriminately and causes a "dysbiosis", which is essentially the collapse of the microbial community structure.

Eight of the 21 participants then took the probiotic mixture to 11 strains twice a day for four weeks, while seven took nothing – the control group. The other six participants received faecal transplants from their own shit before antibiotic treatment (this is an autologous fecal microbiome transplant or aFMT). eye on the inhabitants of the intestine.

In this study, the probiotic strains flourished. In the dysbiotic intestines, probiotic strains have bloomed in the lower gastrointestinal tract, forming stable, active colonies. This may seem like a good thing. However, compared to the control groups and ATMF groups, the probiotic subjects achieved the best results in terms of recovery of their microbial communities. Participants who had a FLMD saw their gathering of healthy Aboriginal people in just one day of their transplants. Those who had nothing after their antibiotics saw their community recover within 21 days.

But the probiotic group – which was now colonized by the probiotic strains – remained in dysbiosis state until five months after its antibiotic treatment. The bacterial burden in their feces was lower and the microbial communities in their lower gastrointestinal tract were still severely disrupted. By digging deeper, the researchers found that probiotic usurpers seemed to stimulate immune responses in the intestines, which could inhibit native microbes. In laboratory studies, the researchers also noted that the probiotic strains seem to secrete unidentified factors that can inhibit the growth of microbiome residents.

Both studies have limitations, of course. They were both young. And other probiotic strains that the 11 tested might prove more useful – or at least less worrying. Probiotics can also be beneficial for different patient populations. In both studies, researchers used healthy adults, while infants, children or the elderly may have different experiences with probiotics. And people with specific conditions could benefit specifically.

Yet in all, the researchers concluded that the use of probiotics "may not be risk free". And in case of stimulation of the microbiome, they conclude:

Like any other medical treatment, [probiotics’] The repulsive activity of potentially beneficial pathogens (which remains to be proven or disproved) may entail a risk of compromising the rate and extent of recolonization of native microbiomes.

Cell, 2018. DOI: 10.1016 / j.cell.2018.08.041

Cell, 2018. DOI: 10.1016 / j.cell.2018.08.047 (About DOIs).