There is an invisible universe hidden inside your body, it’s called the gut microbiome – a huge range of trillions of gut bacteria, hundreds of different species. They help digest food in exchange for a warm and safe place to live. And only now are we starting to discover that the gut microbiome plays a much bigger role in our lives than we ever imagined.
Some of those bacteria found within us are replicated in commercially produced mixtures called “probiotics”. You see them on the grocery and pharmacy shelves and are recommended by your friends and often by doctors like me.
But do probiotics really do something? To find out, you first need to know the gut microbiome.
Dr. Jeff Gordon: This is a snapshot of the microbiome.
Dr. Jon LaPook: And then this is the trillion of bacteria there. They are represented by the different colors.
Dr. Jeff Gordon at Washington University in St. Louis is recognized as “the father of the microbiome”. He has spent decades exploring the mysteries of the bacterial community in our intestines.
Dr. Jeff Gordon: It is a collection of microbes that are able to coexist with us in still unclear ways.
Dr. Jon LaPook: Why am I there in the first place?
Dr. Jeff Gordon: They help process the food we consume, but they do much more. They make vitamins. We think of vitamins as only food. they are able to produce essential amino acids, they are able to talk to our immune system and help educate the immune system.
Dr. Jon LaPook: It is different from how I think the way many people think about the intestinal tract. It’s a kind of tube, food goes in and out, that’s all. But are you saying there is much more than an interaction?
Dr. Jeff Gordon: We are coming to understand it much more clearly. and this ability to transform – the food we consume is linked to our health and disease states.
Research suggests that a healthy microbiome can reduce the risk of diseases like cancer and diabetes. And in an emblematic experiment, Dr. Gordon and his team fattened the mouse by giving it the bacteria of a fat mouse.
Dr. Jon LaPook: Are you saying that part of the cause of obesity could be the type of bacteria found in the gut, in the microbiome?
Dr. Jeff Gordon: I’m saying it. And we see that obese people have a less diverse microbial community than thin people.
Dr. Jon LaPook: Is there any evidence that you could take the microbiome associated with a thin person, transfer it to someone who is overweight and could somehow help him lose weight?
Dr. Jeff Gordon: There is a lot of work to be done right now, trying to test this hypothesis.
Right now, the microbiome is a hot research area. Doctors are already treating the disease by manipulating intestinal bacteria. A potentially life-threatening colon infection called C. Diff. Has been successfully treated by moving bacteria from the gut of a healthy person to the gut of someone who is sick.
And millions of people are trying to improve their microbiomes themselves using probiotics, the so-called “good bacteria”. But here’s the problem: there is a lot of conflict among scientists that probiotics provide no benefit.
Dr. Patricia Hibberd: Over the years there have been so many studies on various probiotics that said “it’s good for this”. The next study says “not good for this”. And really, it’s chaos.
Dr Patricia Hibberd is an infectious disease specialist and professor of medicine at the University of Boston.
Dr. Hibberd has reviewed hundreds of studies in the medical literature on probiotics. He also did his studies and told us that there is not enough high-quality research to recommend standard probiotics for the medical problems for which they are commonly used.
Dr. Patricia Hibberd: The idea that perhaps we could add a good bacterium that we would have taken by mouth that hopefully could land in the right places in the gastrointestinal tract and work with the immune system. We simply don’t know how to do any of this.
Dr. Jon LaPook: But right now, there is a multi-billion dollar industry that is growing.
Dr. Patricia Hibberd: Yes.
Dr. Jon LaPook: And people are out there buying this stuff.
Dr. Patricia Hibberd: Right.
Dr. Jon LaPook: So, is there any convincing evidence that commercially available probiotics have been found helpful in reducing diarrhea from antibiotics?
Dr. Patricia Hibberd: No.
Dr. Jon LaPook: Treating Irritable Bowel Syndrome?
Dr. Patricia Hibberd: No.
Dr. Jon LaPook: reduction of allergies?
Dr. Patricia Hibberd: No.
But probiotics are suggested as a remedy for all those things … and more.
COMMERCIAL ALIGNMENT: your digestive system has billions of bacteria. But life can make them lose their balance.
Restoring that balance of bacteria in the gut microbiome is just one of the goals promoted by probiotic manufacturers, a $ 50 billion global industry sold to us in capsules, popsicles, cereals, tea and yogurt. And we are told that probiotics can even help your dog.
Many doctors and patients believe that probiotics are worth trying and many believe that they work.
One of those doctors is Dr. Dan Merenstein. He is a professor of family medicine at Georgetown University. And it is on the board of an industry-funded, non-profit group that promotes probiotic science.
Dr. Merenstein is doing a clinical trial supported by the National Institutes of Health to test a probiotic cocktail. He is trying to see if he can prevent diarrhea in children taking antibiotics, a remedy that other researchers have tried with mixed results.
Dr. Dan Merenstein: I think the data is there. I recommend probiotics mainly to people taking antibiotics and people with irritable bowel disease.
Dr. Jon LaPook: I wonder what our viewers are thinking right now, right? They are hearing you say, it definitely helps, probiotics and others say, there is no evidence that it helps. Are they throwing a brick across the television screen right now?
Dr. Dan Merenstein: … they are, but they have thrown a brick, you know, in the past 20 years when we tell them that everyone needs vitamin D, and everyone needs, you know, echinacea for a cold or zinc for cold . I think it’s difficult to be a consumer because things change so quickly. But I think we need more probiotic research.
A cause of confusion could be the placebo effect: some people who use probiotics may feel better because they expect to feel better. And understanding what probiotics do inside the gut is complicated. One reason is that each person’s microbiome is unique, so the same probiotic can have different effects on different people. This is exactly what professors Eran Elinav and Eran Segal found at the Weizmann Institute of Sciences in Israel.
Eran Elinav: We wanted to directly evaluate what probiotics were doing and how they interact with what is already inside our intestines.
The researchers collected thousands of samples from a small group of adult volunteers who were given probiotics.
Eran Segal: We have actually looked through the entire gastrointestinal tract in places where no one has ever seen before.
All volunteers underwent multiple endoscopies and colonoscopies.
Dr. Jon LaPook: So you’re going down the swallowing tube, stomach and first part of the small intestine. And then colonoscopy, come from below.
Eran Elinav: Exactly. And then we gave some of these volunteers a very broad combination of probiotics that are out there in your supermarket. And half of the individuals were given what we call placebo, which is an empty pill.
Eran Segal: So the results have been truly amazing, so what we are seeing is that half of the people take probiotics and probiotics as they enter, leave and don’t populate the intestines.
Dr. Jon LaPook: Was it surprising for you?
Eran Elinav: This was very surprising for us, most of us or all of us, we are under the assumption: these probiotics would settle at least temporarily in our intestines and do the good things we expect them to do.
The researchers also studied a treatment commonly recommended by doctors by providing probiotics to help restore the balance of gut bacteria swept away by antibiotics.
Eran Segal: We found that probiotics actually delayed the restoration of those individuals’ bacteria to what they had before compared to individuals who took antibiotics and then did nothing.
Dr. Jon LaPook: So many of us have taken probiotics with antibiotics here because we think maybe this will help us get back to normal more quickly. And this is showing the opposite.
Eran Segal: Exactly.
Eran Elinav: Exactly.
The discoveries of Elinav and Segal contradict much of the conventional wisdom on probiotics. Other scientists are now developing their work.
Eran Segal: To be clear, we are not against the concept of probiotics in general. We actually think that probiotics can have huge benefits.
Eran Elinav: But we have to be very careful in prescribing these microbes in general without knowing enough about what they do.
But we were surprised to learn that probiotics are added to some baby foods and even to the infant formula. About a fifth of the best-selling infant formula in the United States contains probiotics. And the market is growing.
Dr. Frank Greer: Most parents don’t realize how little work there is to support probiotic use in infants.
Dr. Jon LaPook: Still, it is used.
Dr. Frank Greer: it is used.
Dr. Frank Greer is an emeritus professor of pediatrics at the University of Wisconsin. He is co-author of the clinical report of the American Academy of Pediatrics on probiotics.
Dr. Jon LaPook: So when you add probiotics to the infant formula at this early stage, what could happen?
Dr. Frank Greer: I wish I could answer this question, but I think part of the answer is that we don’t really know how probiotics work.
Dr. Jon LaPook: So if we don’t know how they work and aren’t sure what they do, why are we adding them to the formula for children?
Dr. Frank Greer: This is an excellent question. Because we are giving them to children.
Dr. Jon LaPook: Is there any convincing evidence that adding probiotics to the infant formula is positive for the baby?
Dr. Frank Greer: My answer would be no.
That response was unexpected for Dr. Greer. You see, a group of infant formula merchants – the Infant Nutrition Council of America – recommended that they explain their point of view.
Dr. Jon LaPook: So why do we see it in so many different products?
Dr. Frank Greer: Well, it’s easy to insert because it’s not strictly regulated.
The Food and Drug Administration, the FDA, does not classify probiotic capsules as drugs. This means that they do not have to be proven “safe and effective”. When added to anything, including the infant formula, probiotics need only meet a lower standard: “generally recognized as safe”.
In rare cases, probiotics have been linked to serious infections in critically ill patients and in those with weakened immune systems. Otherwise, they seem to be safe
Dr. Jon LaPook: If you could give probiotics early in life and potentially help, those same probiotics along the line could have unintended consequences and injuries?
Dr. Frank Greer: It’s possible, but I can’t attest to any damage whatsoever. There is … there is no evidence that says it is harmful.
Dr. Jon LaPook: But are there any long-term studies?
Dr. Frank Greer: No, there are no long-term studies (LAUGH)
Without these studies, there is no way of knowing whether giving children probiotics has unwanted long-term consequences. The infant formula trade group, which recommended interviewing Dr. Greer, sent us this statement: “In babies fed infant formula, probiotics promote a balance of bacteria in the baby’s gut” and “simulate the benefits provided by breast milk “.
Dr. Frank Greer: Well, I think ultimately the goal of the formula industry …
Dr. Jon LaPook: it’s their goal, but it’s–
Dr. Frank Greer: this is their goal.
Dr. Jon LaPook: That’s what’s going on–
Dr. Frank Greer: This doesn’t. You know? Putting a single probiotic organism into a formula for babies does not promote the balance they are talking about.
Despite the disagreement about how or if today’s probiotics work, every scientist we spoke to was confident of the possibility of improving health by manipulating the microbiome. Last year, Dr. Gordon’s team reported that a special supplemental nutrient mixture containing chickpeas, soybeans, bananas and peanuts can repair the damaged microbiome of malnourished infants.
Dr. Jeff Gordon: think about it. The idea that a defective development of a microbiome could compromise the development of bones, the immune system, perhaps even the central nervous system. How extraordinarily extraordinary is it that our collection of microbes is so impactful? It is inspirational. But the task is complex. We want to be able to develop safe short and long term interventions. And we want to make sure we have it well.
Film produced by Julie Holstein and Howard L. Rosenberg. Associate producer, Deborah Rubin. Broadcasting partner, Jacqueline Kalil. Curated by Joe Schanzer.