The Gut Microbiome's Major Role in our Mental & Physical Health
It’s so important that we start addressing what is most central to our overall mental and physical health: our gut microbiome. Everything truly starts here, yet many health practitioners know little about it or how to care for it properly. My name is Norma Jean Flood, MS, RDN, and I'm an Integrative & Functional Nutritionist guiding adults and teens to better brain balance and gut health.
A Case Study: Ulcerative Colitis & the Power of Nutrition
A few years ago, I worked with a teenage boy suffering from ulcerative colitis. His condition was worsening, preventing him from attending school or participating in sports. His gastroenterologist treated him with immunosuppressants to reduce inflammation and insisted that his condition was genetic, dismissing the role of nutrition entirely.
I was shocked that a specialist in gastrointestinal disorders knew so little about how food impacts the microbiome and intestinal health. I recommended a gluten-free and dairy-free diet and provided guidance on how to implement it. After just two weeks, he was feeling significantly better and relied less on immunosuppressants. Stories like these fuel my passion for exposing the gaps in our healthcare system. Instead of merely managing symptoms, we need to address the root causes of health imbalances.
The Role of the Gut Microbiome
Better health truly begins with the gut. Our microbiome is home to over 100 trillion microorganisms, including bacteria, fungi, viruses, and protozoa. The majority reside in the large intestine, where much of the magic happens. Most of these organisms are bacteria, which is why I often refer to the microbiome as "gut bacteria."
The microbiome plays such a critical role that it is often considered another organ of the body. It acts as a second brain, performs essential metabolic functions, regulates over 70% of our immune system, and even influences how our genes are expressed.
Gut Bacteria and Brain Function
One of the most fascinating aspects of the microbiome is its ability to produce or regulate neurotransmitters—chemicals that affect brain function. Some of these include:
Serotonin: Supports a positive mood, reduces anxiety, and aids memory, learning, and sleep.
Dopamine: Enhances focus, memory, and motivation.
Norepinephrine: Improves energy levels and attentiveness.
GABA: Helps regulate mood and produces a calming effect.
Acetylcholine: Boosts motivation, attention, and learning.
Histamine: Regulates wakefulness and alertness while also playing a role in immune signaling.
What many people don’t realize is that nearly 95% of our serotonin is produced in the gut lining. Gut bacteria regulate serotonin production by controlling tryptophan metabolism. Most medication will try to control how much serotonin remains active in the brain, but its production is the most critical step to address.
The Gut-Brain Connection
So how do neurotransmitters from the gut influence the brain? The answer lies in the vagus nerve, which enables two-way communication between the gut and the brain. While it was once believed that most communication flowed from the brain to the gut, we now understand that the gut sends many signals back to the brain, influencing mood, cognition, and overall well-being.
Gut Health and Metabolism
Our gut bacteria also determine how energy from food is used, playing a major role in metabolism. Previously, we thought the microbiome’s primary function was to break down undigested fiber. However, we now know that it produces essential byproducts such as:
Vitamin K: Crucial for blood and bone health.
Fatty acids: Support intestinal health and aid in the absorption of calcium, magnesium, and iron.
This is why gut health is also directly linked to bone health.
The Immune System and the Microbiome
Since over 70% of our immune cells are in our gut, our microbiome also plays an important role in regulating our immune system, which includes fighting against pathogens. Hence, those with healthy microbiomes will get sick less often and have a lower risk for allergies.
Genetic Expression and the Microbiome
The microbiome also influences genetic expression, impacting immune responses, metabolism, brain function, and the integrity of the intestinal barrier. This barrier controls what enters the bloodstream from digested food, affecting overall health.
Subscribe to Learn More
This is just a brief overview of the microbiome’s vast influence on brain function, metabolism, immunity, and genetic expression. To learn more, subscribe to my YouTube Channel at youtube.com/@normaflood, where I’ll be sharing weekly videos with strategies to help you build a stronger foundation for gut health, mental health, and well-being.
About the Author: Norma Flood, Integrative & Functional Nutritionist
Norma Flood is a busy mom, wife, friend, and Registered Dietician Nutritionist guiding adults and teens to better brain balance and gut health. Holding a Master of Science in Nutritional Sciences, she is recognized as one of San Diego’s top Integrative and Functional Nutritionists. With a deep commitment to holistic well-being, Norma provides personalized health counseling and applies functional nutrition therapy to effectively support digestive health, mental health, and eating disorder recovery. She offers both in-person and group counseling as well as online education. Follow Norma Flood on YouTube as she shares small, easy steps that you can take each day to support better gut health and mental health using an integrative and functional approach.