Probiotics: Solution to long-COVID or overhyped sales pitch?

Credit: Natural Ingredients Asia
Credit: Natural Ingredients Asia

“Could THIS twice-daily probiotic supplement filled with gut friendly bacteria help beat Long Covid?” That’s the headline in the Daily Mail earlier this year, one of dozens in the media across the web promoting the miracle of probiotics.

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Dozens of other news outlets, from Psychology Today to Medical News Today carried the same unfiltered story. Taking a probiotic supplement, they report, could improve COVID recoveries by promoting the “right mix of gut bacteria” to “boost the body’s immune defenses”.

These are not new claims. Since the COVID crisis commenced more than two years, and based on a few sketchy and inconclusive studies, ‘natural’ websites have been making claims that probiotic supplements could be the magic bullet to halt or even cure COVID.  According to NUTRA Ingredients, which peddles supplements “a probiotic formulation could act as a complementary remedy to slow down the progression of COVID-19.”

Is it too good to be true?

The answer is ‘yes’ but with nuance. 

The most recent surge in articles was sparked by a small study out of Bhatia Hospital, Mumbai that suggested ‘Long Covid’ may be dictated by the microbes in our gut and that probiotics could hold a solution. “The gut microbiome is involved in the magnitude of COVID severity — possibly via modulating host immune responses,” they claimed.

This represents another in a line of studies that seem to support the idea that rebalancing the bacteria in our gut may help fight long-term COVID symptoms. In December, for example, researchers at Cambridge University Hospitals (CUH) NHS Foundation Trust presented data claiming to demonstrate that “two capsules a day containing a scientifically chosen blend of natural ingredients could help patients suffering from long COVID”. 

Oncology consultant Prof Robert Thomas was quoted as saying, “Such a rapid improvement in the majority who had been experiencing symptoms for over eight months was clinically relevant and welcomed, especially among those more likely to have pre-existing gut dysbiosis.”

But most scientists and researchers are more dubious. Certainly, there is no question that our gut bacteria is linked to our health. Whether tinkering with our gut bacteria using supplements can meaningfully help address COVID, or any disease for that matter, is far more problematic. 

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Skepticism

Since COVID first appeared two years, probiotic devotees have been promoting salves and supplements, claiming that they could boost your immunity and ward off the coronavirus. But the curative claims of probiotics has been met with raised eyebrows from the medical and scientific world.

There is widespread evidence that gut bacteria is linked to our health—it’s just that probiotics have not been shown to improve it as an aid to battling COVID. 

The National Academies of Sciences, Engineering and Medicine have responded to the COVID claims with skepticism: “There is currently no evidence that taking probiotics can prevent or treat COVID-19”. They encourage consumers to “beware of false claims about COVID-19 cures”. 

Akiko Iwasaki, an immunologist at Yale University, was an early voice of caution, challenging probiotics as a COVID-fighting tool.  As he told the BBC, the idea that pills, trendy superfoods or wellness habits can provide a shortcut to a healthy immune system is a myth. In fact, the concept of “boosting” your immune system doesn’t hold any scientific meaning whatsoever.

“The problem is that many of these claims have no grounding in evidence”. This idea was viewed as a case of “pseudoscientists are peddling trendy products such as kombucha and probiotics”. 

In other words, this idea may be too good to be true for a reason. Such claims during health crises have a long history. During the Spanish flu crisis a century ago, Vick’s VapoRub offered itself as special treatment along with taking laxatives. Crises breed opportunity, and sometimes snake oil salesman. Is that what’s going on here?

Dubious claims

Certainly, many of the sites promoting probiotics do their best to make it seem their over-the counter and unregulated probiotic products are medical magic. Take one example claiming to present a “New breakthrough study in overweight adults on a weight loss program”. It is clear to any objective eye that this is an advertisement with the product taking front and center and minimal information about the alleged supporting study:

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Other ads are a little more subtle. Headlines like “Shelf-stable or refrigerated: Which probiotic is better for you?” or “5 surprising signs you probably need a probiotic” are designed to convince the reader into thinking there is scientifically useful information to back up the claims. 

But that’s not what you find when you “Go to the breakthrough study results”. Instead, you are transported via hyperlinks to supplements and products along with disclaimers stating, “Any products featured in this article are selected by our editors, who don’t play favorites. If you buy something, we may get a cut of the sale.”

Many promotional websites contain information that is not only scientifically tenuous, but contrary to the latest data. One common example: articles promoting the use of probiotics to counter gut bacteria loss after a course of antibiotics. This is a popular sales pitch but, unfortunately, data such as this study from the Weismann Institute in Israel suggests this is not such a good idea. Immunologist Dr. Eran Elinav explains:

The evidence for taking probiotics after antibiotics is a little murky and contradictory, but the public perception of many people and some doctors is that this is a good idea, even without substantial medical evidence.

Contrary to the current dogma that probiotics are harmless and benefit everyone, these results reveal a new potential adverse side effect of probiotic use with antibiotics that might even bring long-term consequences. We need to be cautious about recommending this until further knowledge emerges.

To date, no probiotic has been FDA approved for clinical use, yet supplements flood the market as they remain unregulated in the US and many other countries.. “Marketing of product is often geared directly at consumers without providing direct and consistent proof of effectiveness,” notes the American Gastroenterological Association.

So how did this latest probiotic craze gain traction?

Let’s review the science.

The concept of utilizing probiotics as “COVID cures” appears to have emerged from multiple studies that suggested the cause may lie within our digestive tract. More specifically, the ~100 trillion bacteria and microorganisms within our gut microbiome. They are a key part of our digestive system. Whenever we eat something, it needs to be broken down so that the nutrients can be absorbed and processed by our body. We cannot do this alone. We require assistance from our gut microbes, particularly in the case of complex carbohydrates and fibers. The bacteria in our gut breakdown and ferment these components and release products that can be utilized by our body. 

The gut microbiome has been linked to many chronic illnesses in the past but the actual impact it has is often debated and data can be tenuous at best. Now, a new set of claims that “taking a capsule of probiotics, which are designed to boost the number of beneficial bacteria in the gut, may speed up recovery from the coronavirus” are gaining traction. 

This is further fueled by an initial study from The Chinese University of Hong Kong that reported an increased presence of harmful and pathogenic bacteria in COVID patients with severe/long-term illness. When paired with the depletion of immune-boosting gut bacteria, the reports suggest that the gut microbial changes could directly relate to an increased risk of developing long-COVID. This has led to some concluding that probiotic supplements could be a way to protect against or treat long term complications of COVID-19 by rebalancing such changes in our gut microbes. Prof Siew NG, head of the study, concluded:

The most surprising findings were that different bacteria patterns were associated with different categories of Long Covid symptoms such as respiratory, neurological, gastrointestinal, hair loss, etc. Such patterns were characterized by a higher level of “unfriendly” microbes and lower levels of “friendly” microbes.

It sounds promising but suggestive news based on incomplete research should always be approached with a considerable caution. First, COVID pathology is complex. It involves a cascade of immune events that can trigger serious consequences in a number of areas of the body. In the words of John Wherry, director of the Penn Medicine Immune Health Institute, “COVID is deranging the immune system”. 

Second, and more importantly, we should be wary of studies that play into the billion-dollar probiotic industry narrative that untested products hold the ‘silver bullet’ for complex healthcare issue.

According to the Mayo Clinic online, “there is no clear evidence that probiotics are beneficial,” let alone a potential silver bullet to treat COVID. 

For the most part, probiotic supplements have no measurable impact on your gut microbiome diversity and may actually cause harm in some instances. Dr Matthew Ciorba, a gastroenterologist at Washington University in St. Louis, echoes this message, saying, “There is no evidence to suggest that people with normal gastrointestinal tracts can benefit from taking probiotics.”

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Many supplement suppliers claim their products “optimize your gut.” That’s mumbo jumbo. The average probiotic supplement contains ~2 billion bacteria. That sounds like a lot but when you consider those 2 billion will only account for 0.002% of the 100 trillion microorganisms in your gut, it’s a bit like dropping a salt particle into a gallon of maple syrup and expecting it to taste salty. The impact will be minimal to non-existent in all but a few specific cases of digestive issues. 

“Everyone else can save their money, because there’s no evidence that probiotic supplements offer any benefit to already healthy people,” says Prof Jack Gilbert, founder of the American Gut Project.

Beyond the hype

So why does the hype around a probiotic COVID cure persist? Greed and bad reporting, for the most part.

It is often generated by cherry picking of data by websites seeking to promote sales of supplements. Many of the probiotic websites are trying to leverage fear generated by COVID to make a sales pitch for other probiotic supplements.

Once you get past the ‘miracle COVID cure’ headlines, many articles actually report more sober and less encouraging findings. One article claiming probiotics can treat COVID, for example, included a quote from a researcher in the field: “It is not that the use of one probiotic will reduce all the problems caused by COVID-19”, with the article going on to state that “the best case for probiotic therapy has been in the treatment of diarrhea”. Hardly the COVID are touted in the headline!

The Daily Mail led with the claim that “now it seems our gut bacteria can also tackle COVID-19”. However, further into the article, the authors of the study are quoted as being much more measured. Professor Andrew Smith (Medical Sciences) offered this measured take on his findings along with a warming about taking probiotics:

The study excluded those over 60 and did not account for whether volunteers had been vaccinated or not. So, we don’t know if probiotics provide any benefit to those most at risk of severe Covid. And taking probiotics may be inappropriate for those with a weakened immune system because of the potential increased risk of infection from consuming large quantities of live bacteria.

But probiotics are at least harmless, right?

If I want to take it as a precaution surely there is no downside to trying it?

Unfortunately, that may not be the case. According to research from 

Eran Elinav of the Weizmann Institute of Science, taking probiotics in certain scenarios can actually cause harm:

The probiotics very potently and persistently prevented the original microbiome returning to its original situation. … This was very surprising and alarming to us. This adverse effect has not been described to date.

So there is a risk, however minimal, in taking probiotic supplements in the hope of avoiding complications of COVID-19. When you pair that with the lack of tangible evidence of its benefits, there is not much of a case for probiotics as preventative or acute therapy. 

It is very difficult to find any reputable medical professional promoting probiotics as COVID treatments. For the most part, the idea is being pushed forward by supplement pushers, diet promoters or people that will sell you a handy and expensive course to help you “optimize your microbiome”. 

Proceed with caution when articles claim you can cure disease by changing the bacteria in your gut. Especially when they claim you can start healing yourself with a convenient, over the counter probiotic pill—one that your doctor would never prescribe. It’s a snake oil salesman pushing miracle cures. 

Sam Moxon has a PhD in tissue engineering and is currently a research fellow in the field of regenerative medicine. He is a freelance writer with an interest in the development of new technologies to enhance medical therapies. Follow him on Twitter @DrSamMoxon

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