By Dante Moroni

Note: The statements below are only my opinion and are not to be taken in any way as medical advice.

Dr. Emeran Mayer is a distinguished research professor of medicine and psychiatry who has completed specialty training in gastroenterology at UCLA, is an author on over 300 peer reviewed scientific articles, and is the founder of the UCLA Brain Gut Microbiome Center. Unfortunately, in my opinion, the book does not reflect these credentials and I would really only recommend it for those very interested in the gut microbiome.

Overall Book Rating: 5/10

Why is healthcare in the US the most expensive in the world, while ranking nowhere near the top? The answer to this question is complex. One area that research has spent time focusing on is the gut microbiome. In 2007 the NIH launched the Human Microbiome Project and this combined with other research projects has vastly increased our understanding of the microbiome. However there is still debate as to the significance of a person’s individual gut microbiome and health. Emeran Mayer has spent a lot of time looking at the connection between gut microbes, the enteric nervous system, and the brain. He believes that gut microbes have more power than we currently understand and may be the clue to returning to a healthier state.

However, one must be careful when writing science communication directed to translate complicated scientific information to the public. I fear that Mayer made some mistakes than detract from the book’s credibility and stature. First off, the book’s references aren’t organized whatsoever so it is difficult to check Mayer’s statements against the evidence. My next problem is the vast amount of speculative conclusions he draws from incomplete studies and data. Finally, the scientific writing is too dumbed down for the lay reader than I think is needed.

The Good

• Explains why antibiotics should be used with caution as they may disrupt a healthy microbiome.
• Delves into the history of some of the first gastric digestion experiments.
• Introduces the reader to the Enteric Nervous System (ENS) and Vagus Nerve.
• Hypothesizes on importance of phytochemical gastrointestinal “taste” and “smell” receptors.
• Focus on gut serotonin and its influence on digestion and mood.
• Much weight given to metabolite production from gut microbes, rightly so.
• Identifies stress as a major trigger for negative gut symptoms.
• Expert description of the brain/nervous system’s salience system.
• Highlights how breast milk oligosaccharides crucial for healthy development on infant microbiome.
• Conveys why added food thickeners/emulsifiers are harming our health by affecting gut bacteria.

The Bad

• Often leans towards anti-medical / holistic / naturopath paradigm.
• Zealot like over estimation of microbial capabilities / influence on health.
• Not enough hard science references cited in text and too much speculation. Repetitive.
• Seems to hold Freudian psychiatric based thoughts and puts too much weight on trauma / early life experiences and not enough credit to the human/brain resiliency and plasticity.
• Speaks on “healing/fixing” problems his patients have had although who’s to say if they regressed/got worse… Very anecdotal at times.
• Incorrectly states that artificial sweeteners spike your insulin.
• Doesn’t seem to understand the importance of diet on IBS symptoms.
• Subscribes to outdated false low fat diet dogma.
• Completely and unfairly demonizes animal fat, also doesn’t account for omega-3s.
• Falsely says that microbial GABA is able to reach the brain and affect mood directly.
• No mention of influence of carbs on fat storage and satiety.
• Disregards and doesn’t recognize non-celiac gluten sensitivity.