The Gut-Brain Connection: How Your Gut Microbiome Can Affect Your Mental Health
Previously, it was believed that the mind and body operated as two separate systems. If something was wrong with one, it didn’t affect the other. That has since been proven to be incorrect. There is an established body of research indicating that gut health can affect physical health, and vice versa. There is also a growing body of research to indicate that it can impact your mental health and mood, too. So how is this possible?
The Gut-Brain Axis
The gut-brain axis refers to the network of connections that allows for the bidirectional communication pathway between these systems. This communication is done via the vagus nerve. There is a balanced variety of microorganisms that live within our gut. Beneficial bacteria help synthesize several B vitamins and vitamin K. It’s estimated that a healthy gut can provide up to half of the daily requirement for vitamin K. The beneficial bacteria in our digestive tract also influence the body’s production and metabolism of hormones, aid in appropriate immune response, influence metabolic health, and help produce neurotransmitters that affect our mood and mental state.
About 95% of serotonin (5-HT) is produced by beneficial gut microorganisms. These organisms also play an important role in metabolism of the amino acid tryptophan, which serves as a precursor to the production of serotonin. A deficiency of serotonin can contribute to depression and anxiety. Other mood-related neurotransmitters that gut microorganisms help to produce include GABA and dopamine (Dicks, 2022).
The beneficial impact on health related to these microorganisms is clear, and future research strives to deepen our understanding of these processes. The relationship between these microorganisms and humans is referred to as a symbiotic relationship, meaning that it is mutually beneficial between host and organism. Other microorganisms that cause harmful effects on health are also able to inhabit the gut, resulting in dysbiosis, or an imbalance of beneficial vs. pathogenic bacteria.
Factors that Shape and Affect the Gut Microbiome
Some of the factors that can affect the composition and diversity of the microbiome include diet, genetics, age, antibiotic use (frequency and duration), mode of birth, lifestyle factors (smoking, exercise), and environmental exposures (pollution, chemicals). While some of the things that shape our gut microbiome are out of our control, there are many things that we can be mindful of to help support a healthy microbiome.
Diet and Lifestyle for a Healthy Microbiome
An overall healthy dietary pattern that emphasizes lean proteins, a variety of fruits and vegetables, whole grains, and healthy fats will support a healthy microbiome. Beneficial bacteria use fiber as a fuel source, so getting enough fiber from a variety of sources like fruits, vegetables, whole grains, nuts, seeds, and legumes is important to increase the composition and variety of beneficial bacteria. Many foods high in fiber are considered “prebiotic”, since they contain the necessary fuel for these microorganisms. Examples of these prebiotic foods include:
Garlic
Asparagus
Bananas
Onions
Oats and rye
Chicory root
Artichokes
Apples
Fermented foods can serve as a natural source of probiotics. Examples of these foods include:
Yogurt and other fermented dairy products
Kefir
Kimchi
Sauerkraut
Sourdough bread (made via a different fermentation process than traditional yeast bread)
Apple cider vinegar
Kombucha
Tempeh
Pickles
Other lifestyle factors that can promote a healthy microbiome include regular exercise, abstinence from tobacco and tobacco products, stress management (stress hormones can impact the microbiome), adequate sleep, and limiting harmful environmental exposures.