The Different Gut Axes: How Gut Health Affects the Brain, Skin, Liver, Lungs and Metabolism
Most people have heard of the gut–brain axis by now. The idea that your gut health can influence your mood, stress levels, and cognitive function has become pretty mainstream in the wellness world.
But what many people don’t realize is that the gut communicates with far more than just the brain.
Emerging research shows that the gut microbiome interacts with multiple organs throughout the body through a network of communication pathways often referred to as “gut axes.”
This means that when gut health becomes imbalanced, symptoms may show up in places that don’t seem digestive at all—like the skin, the liver, or even blood sugar regulation.
As a functional nutritionist, I focus heavily on restoring gut health, because the digestive system plays a foundational role in overall wellness.
Let’s start with why the gut is so important in the first place.
Why Gut Health Is So Important
Approximately 70–80% of the immune system lives within the gastrointestinal tract, in a specialized immune network known as the gut-associated lymphoid tissue (GALT).
This makes sense when you think about it.
Your digestive tract is constantly interacting with the outside world. Every bite of food, sip of water, and microbe that enters the body passes through the gut. Because of this, the immune system stationed there must constantly evaluate what is safe and what is not.
The gut lining and immune system work together to:
Identify pathogens
Neutralize harmful microbes
Maintain tolerance to harmless substances like food proteins
When gut health is balanced, this system works quietly and efficiently.
But when the gut microbiome becomes disrupted, it can trigger a cascade of immune and inflammatory responses throughout the body.
What Is Gut Dysbiosis?
Gut dysbiosis refers to an imbalance within the gut microbiome—the ecosystem of trillions of microorganisms that live in the digestive tract.
Dysbiosis can be defined as:
Certain bacteria overgrow
Beneficial bacteria decline
Microbial diversity is reduced
Many of the beneficial microbes that live in our gut produce substances called short chain fatty acids, that directly benefit and support the gut lining. When we have dysbiosis, oftentimes the gut lining becomes compromised as well because it does not have the nutrients it needs to thrive.
When the gut lining becomes weakened, a condition sometimes referred to as increased intestinal permeability, substances that normally stay within the digestive tract can enter the bloodstream.
These may include:
Bacterial fragments
Microbial toxins
Undigested food particles
Environmental toxins
Once these substances enter circulation, the immune system reacts. This can lead to systemic inflammation, which often manifests in tissues far away from the gut.
In other words, a gut issue may present as symptoms somewhere completely different in the body.
This is where the concept of gut axes becomes important.
The Gut–Brain Axis
The gut–brain axis describes the communication network between the gastrointestinal tract and the central nervous system.
This connection occurs through several pathways, including:
The vagus nerve
Immune signaling
Hormonal signaling
Microbial metabolites produced by gut bacteria
Certain gut microbes can produce neurotransmitters and signaling molecules that influence mood, stress responses, and cognitive function.
This is one reason digestive issues are often associated with symptoms such as:
Anxiety
Brain fog
Mood changes
Sleep disturbances
The Gut–Skin Axis
Another important connection is the gut–skin axis, which links the gut microbiome with skin health.
The gut microbiome helps regulate inflammation and immune responses throughout the body. When gut dysbiosis occurs, inflammatory signals originating in the gut can influence the skin.
Research suggests that gut microbial imbalance may contribute to conditions such as:
Acne
Eczema
Rosacea
Psoriasis
In some cases, skin symptoms may reflect underlying imbalances in the digestive system.
The Gut–Liver Axis
The gut–liver axis describes the close relationship between the digestive tract and the liver.
These two organs are directly connected through the portal vein, which transports nutrients—but also microbial metabolites and toxins—from the intestines to the liver.
When gut health is balanced, the liver efficiently processes and detoxifies these compounds.
However, gut dysbiosis may increase the flow of bacterial toxins and inflammatory molecules to the liver. Over time, this can contribute to liver inflammation and metabolic dysfunction.
Researchers are increasingly studying this axis in conditions such as non-alcoholic fatty liver disease (NAFLD).
The Gut–Pancreas Axis
The gut–pancreas axis is an emerging area of research exploring how the gut microbiome influences metabolic health.
Gut bacteria can affect the function of pancreatic islet cells, which are responsible for insulin production.
Changes in the gut microbiome may influence:
Glucose regulation
Energy metabolism
Insulin sensitivity
This connection is one reason scientists are exploring the role of gut health in metabolic conditions such as type 2 diabetes and insulin resistance.
The Gut–Lung Axis
Another emerging connection researchers are exploring is the gut–lung axis.
The gut microbiome plays an important role in shaping immune responses throughout the body, including in the respiratory system. Because the immune system is so closely tied to the gut, disruptions in the gut microbiome can influence how the body responds to respiratory triggers.
Research has shown that gut dysbiosis is associated with conditions such as asthma, allergies, and other inflammatory airway diseases. Changes in the gut microbiome can alter immune signaling and inflammatory responses that affect lung health.
Scientists believe this communication happens through immune mediators, microbial metabolites, and inflammatory signaling molecules that travel between the gut and lungs. In other words, what happens in the gut doesn’t stay in the gut—it can influence how the immune system behaves in the respiratory tract as well.
Why Gut Health Matters for the Whole Body
The gut–lung axis is just one example of the many ways the gut communicates with other organs in the body. Researchers are continuing to uncover additional gut–organ connections, and while many of these pathways are still being studied, the overall message is becoming clearer.
The gut microbiome may influence far more systems than we once thought.
Because of this, improving gut health is often one of the most powerful starting points when addressing overall health concerns. By supporting digestion, strengthening the gut barrier, and restoring balance to the gut microbiome, we may also be supporting the health of multiple systems throughout the body.
Sometimes the most meaningful place to begin is with the gut.
How to Restore Gut Health
If gut dysbiosis is contributing to symptoms, the most important step is identifying the root cause of imbalance.
Functional stool testing, such as the GI-MAP, can provide insight into key markers of gut health, including:
Bacterial balance
Pathogens
Parasites
Viral markers
Inflammation markers
Gut barrier integrity
Rather than guessing, testing can help guide a targeted strategy for restoring the gut microbiome.
Once imbalances are identified, I often use the 5R framework to support gut healing:
Remove – eliminate pathogens, irritants, or inflammatory triggers
Replace – support digestion with enzymes, stomach acid, or bile support
Reinoculate – introduce beneficial bacteria through diet or probiotics
Repair – support the intestinal lining with targeted nutrients
Rebalance – address lifestyle factors such as stress, sleep, and nervous system regulation
Supporting gut health is not about a single supplement or quick fix—it’s about restoring balance to the entire digestive ecosystem.
The Bottom Line
Gut health affects far more than digestion.
Through complex communication networks like the gut–brain axis, gut–skin axis, gut–liver axis, and gut–pancreas axis, the gut microbiome plays a major role in immune function, inflammation, metabolism, and overall wellness.
So when symptoms show up in the brain, skin, liver, or metabolic system, it may be worth asking an important question:
What’s happening in the gut?
Ready to Improve Your Gut Health?
If you're experiencing symptoms like digestive issues, brain fog, skin flare-ups, fatigue, or stubborn inflammation, gut imbalances may be playing a role.
Through comprehensive stool testing and a functional nutrition approach, we can identify what’s happening within your gut microbiome and create a personalized plan to restore balance using the 5R framework.
If you're ready to start addressing gut health at the root level, you can learn more about working with me or book a consultation here:
Because when we support the gut, we often end up supporting the entire body.
Alexandra is a Certified Holistic Nutritionist specializing in mood, stress, cognitive health, and gut heath.
Let’s work together.
You can explore my 1:1 coaching services HERE, designed to support stress recovery, nervous system balance, digestion, and long-term wellbeing.
And if you’re craving deeper answers, I also offer specialized testing — including GI mapping, cortisol testing, DUTCH hormone, and mineral analysis — so we can create a plan that’s tailored to your unique physiology.