Microbiome

The microbiome is an exciting and new area of research. However, the very large majority of claims made about the microbiome and health are not supported by current evidence. Except for some very limited cases (like antibiotic-induced diarrhea and C. difficile infection), research is not yet at a point where we can make claims about specific products and their effects on our gut microbiome. Claims that changes in the gut microbiome are responsible for autism or that restoring the microbiome by buying someone’s special supplement can cure it are not grounded in evidence and there is little to no data on safety and efficacy of these supplements.

Mostly, when it comes to the microbiome, there is a lot that we don’t know and many questions undergoing active research. It’s certainly possible that someday we will have targeted microbiota treatments for a variety of conditions. However, today, any claims made that we can do that are, at this point, hype. This doesn’t mean these things don’t work, just that we don’t have evidence for their safety or efficacy yet. It is important to consider this when claims are made regarding the microbiome in health.

This recent article in Forbes, Keep Calm and Avoid Microbiome Mayhem, discusses how pseudoscience can easily step in at the edges of scientific knowledge and take advantage of consumers.

Some quotes from scientists who study the microbiome (from the above article):

  • “[T]here is harm in giving false hope to people with all kinds of chronic conditions,” says Dr. Elisabeth Bik, Research Associate at Stanford School of Medicine, who writes a daily digest of scientific microbiome papers at the Microbiome Digest blog. “Microbiome research is still a very young field, and it is much too early to claim that we know how to use our microbiome to solve chronic heart and gut conditions, autoimmune diseases and diabetes.”
  • Dr. Melanie Thomson, Lecturer in Molecular Medicine at Deakin Medical School and Geelong Centre of Emerging Infectious Diseases in Victoria…knows firsthand the tangible damage that hyped health claims cause. Recently diagnosed with tumefactive multiple sclerosis and a mom of a child with high-functioning autism, she regularly refutes well-meaning advice and theories about her son’s condition as well as her own.“[T]he real harm comes from people deciding to move away from evidence based medicine and clinically effective treatments, based on these types of pseudoscience-based personality cults,” she says. “Spend money on shoes, not woo,” laughs the Louboutin aficionado.
  • Dr. Jonathan Eisen, Chair of the Advisory Board at PLoS Biology and professor at the Genome Center at the University of California (UC), Davis…echoes Bik’s and Thomson’s sentiments. When asked whether microbiome research is the latest hyped fad or if it will lead to discoveries that will enable actionable treatments, he says it’s a combination of both. “I personally think the microbiome of plants and animals including humans is critically important to understand and likely plays important roles in all sorts of important functions,” Eisen explains. ”Because it is really complicated, it is easy for scam artists to get involved and it is also easy for mistaken conclusions to be made by the well-intentioned. But the hype is so strong that everyone is converging on the area.  Some of those converging on the area are doing phenomenally interesting and important work.  But it is REALLY REALLY early in the field and we just don’t know what is going on in most cases.”

Eisen outlines three rules for separating legitimate info about microbiome research.

  1. If people make claims about conspiracies of scientists and doctors hiding the truth, question what they are saying.
  2. If people don’t cite any scientific studies but instead cite anecdotes and testimonials and self-written books, question what they are saying.
  3. If people have a history of making misleading claims…then question what they are saying.  A lot.

An editorial in the prestigious journal Nature discusses the important questions that must be answered regarding microbiome research (or any research, to be honest). Here’s the TL;DR version.

  1. Can we detect differences that matter?
  2. Does a study show causation or just a correlation?
  3. Is there a plausible mechanism for the reported association?
  4. Do the experiments reflect reality?
  5. Can anything else explain the results?

The Science: Autism and the microbiome

For information on GI symptoms in autism please visit the “Diet” page. It is important to note that it is difficult to sort out the direction of causality between food preferences, microbiome changes and GI symptoms.

A 2015 commentary, The tantalizing links between gut microbes and the brain, in Nature concludes with the following about the state of microbiome research.

There is much more to unravel, she says. “I’m always surprised. It’s very open. It’s a little like a Wild West out there.”

This review, The microbiome and childhood diseases: Focus on brain-gut axis, from 2015 contains a section reviewing the current knowledge about the role of the gut microbiome in gastrointenstinal symptoms associated with ASDs. The authors conclude:

Clearly more research is necessary in order to assess the correlation of early-life factors such as maternal immune activation, antibiotics, and mode of delivery on the development of autistic spectrum disorders, as well as the amelioration of symptoms through manipulation of the gastrointestinal microbiota.

If dysbiosis is shown to be a precipitating factor in ASD, then several potential therapeutic approaches ranging from prebiotics, postbiotics, synbiotics, fecal transplantation, and other strategies used to alter the microbiomes or products may be useful adjuvant treatments in these patients. Preliminary data provide initial support for their usage; however, all of these potential therapies need to undergo rigorous testing before such huge claims can be made regarding their efficacy. In summary, to date, the data provide some evidence linking the microbiota-gut-brain axis to ASD, but the field is still in its primordial stages.

Yet another 2105 review, Potential Etiologic Factors of Microbiome Disruption in Autism, discusses the preliminary nature of what is known about the gut microbiome in autism and the importance of further research into how to modify the microbiome to benefit health.

It is clear that we are at the very early stage of understanding the effect of the microbiome on indi- viduals with autism. Technology has just begun to allow assessment of individual species in patient populations as well as quantification of species. We are still learning the function and value of particular intestinal bacterial communities in health and disease.

Further Reading: Microbiome

All three of the scientists quoted above have blogs with current information about the microbiome.

Dr. Elisabeth Bik blogs at Microbiome Digest where she posts collections of new papers about the microbiome. Explore the autism tag for posts specifically about the microbiome in autism.

Dr. Mel Thompson blogs here.

Dr. Jonathan Eisen blogs at Phylogenomics where he writes about current microbiome research, “microbiomania” (overselling the microbiome),  and overstated press releases about scientific studies.