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Is Your Microbiome Making You Crazy?

Anxiety, depression, brain fog, mood disorders, mood swings or just feeling out of sorts? It’s possible that the answers may lie in the health of the trillions of bacteria living in the intestine called the gut microbiome.

There is a profound connection between gut flora composition and mood. Depending on the different types and quantities that are prevalent, these bacteria can influence everything from the immune system, digestion, DNA expression, inflammation and brain function — for better or worse. Bacteria are even known to play a role in serious conditions like autism and schizophrenia. Put simply, a balanced microbiome equals good health, but the opposite is true as well.

Things that contribute to unhealthy microbial balance include:

  • Frequent and long-term antibiotic use
  • Processed foods, sugar and low fiber
  • Overconsumption of meats and fat
  • Consumption of conventionally raised meat routinely treated with antibiotics
  • Stress
  • Heavy alcohol use
  • Long-term proton pump inhibitor use (i.e. Prilosec and Nexium)
  • NSAID use
  • Being born through C-section rather than vaginal birth
  • Receiving formula rather than breastfeeding
  • Birth control pills
  • Chlorinated drinking water
  • Environmental chemicals and toxins

The digestive tract is not only home to bacteria, but it also houses the majority of the immune system and our “second brain,” called the enteric nervous system (ENS). All three work very closely together to create our health and the way we experience the world.

The ENS is comprised of millions of neurons embedded within the wall of the intestine. It sends and receives signals and information, responds to emotion and has control over what happens locally. This is what most of us refer to when talking about gut instincts: our inner knowing that guides us in decision-making and helps us to react in a split-second to threats, the environment and surprises.

Microbes are another dimension of the second brain, directly affecting the type of information that is sent and received. Neurons in the brain and the ENS rely on chemical messengers called neurotransmitters, many of which are actually made by bacteria. GABA works to calm areas of the brain that may become overstimulated during stress and anxiety. Dopamine, noradrenaline, acetylcholine and serotonin send other types of messages. The way our two “brains” talk is highly dependent on the types of bacteria that are prevalent.

The connections run deeper when looking at the main communication pathway, called the vagus nerve. It was once thought that the majority of signals went directly from the brain to the gut. We now know that 80 to 90 percent of all signals actually run from the ENS to the brain, greatly affecting mood and function. Research has shown that the presence of certain bacteria may be a triggering factor associated with the onset of depression, by overstimulating the immune system. Chronic intestinal inflammation is linked to anxiety while patients with chronic intestinal conditions often have accompanying mood disorders. There is now a lot of science to support probiotic supplementation as a means to improve balance, calm, optimism, determination and even decrease levels of the stress hormone, cortisol.

While the gut/brain connection is intricate and complicated, different microbial imbalances come with unique biological footprints. A specialist in microbiome medicine will be able to run appropriate testing and apply the best treatment strategies to help you get on the road to happy.

Pre- and probiotic supplementation creates a positive psychology effect. This goes far beyond reducing symptoms of anxiety and depression. It helps restore a primordial happiness — a deeper, truer sense of well-being than can be found by taking prescription drugs. Psychobiotics is a new field that uses targeted bacteria to affect and treat mood disorders, improving brain function and creating a sense of calm that radiates from the inside out.

Diet can be the game-changer when it comes to lowering inflammation, rebalancing bacteria and improving brain function. The Microbiome Diet focuses on the health and well-being of friendly bacteria in the intestine. By removing foods that promote pathogenic colonies, and instead including high-fiber superfoods that support friendly microbial balance, dramatic shifts in health and mood can take place.

Additionally, studies show that stressed-out people have less friendly gut bacteria, so take steps to increase the peace and tranquility within your life, and be sure to get a good night’s sleep — every night. When our circadian rhythm is off, so is our microbial balance.

Intestines image available from Shutterstock

Is Your Microbiome Making You Crazy?

Raphael Kellman, MD

Dr. Raphael Kellman, MD, is founder of The Kellman Center for Functional and Integrative Medicine. He is a pioneer in functional medicine and uses a holistic and visionary approach to healing. As a doctor trained in internal medicine at the Albert Einstein College of Medicine in New York, Dr. Kellman uses the latest drugs and technology to treat specific diseases, but his approach to medicine is patient-centered and holistic. Drawing on the latest research, Dr. Kellman addresses a patient’s biochemistry, metabolism, hormones, genetics, environment, emotions, and life circumstances to help them achieve optimal health. Dr. Kellman is also the author of three best-selling books including The Microbiome Diet, Gut Reactions, and Matrix Healing.

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APA Reference
Kellman, R. (2018). Is Your Microbiome Making You Crazy?. Psych Central. Retrieved on October 21, 2020, from
Scientifically Reviewed
Last updated: 8 Jul 2018 (Originally: 29 Dec 2015)
Last reviewed: By a member of our scientific advisory board on 8 Jul 2018
Published on Psych All rights reserved.