Enhance Your Gut Microbiome for Brain & Overall Health

These are my notes from The Huberman Lab Podcast episode #61. I am a BIG fan of Dr. Huberman and his podcast.

This episode taught me the importance of gut health for overall health and well being. The connection between the gut and the brain has a profound impact in our health, and we should really be trying to enhance these functions to have a better life.

I have been trying to incorporate more fermented foods in my diet. Knowing about the key role of the gut microbiome in supporting our mental and emotional health was just the boost that I needed.

Gut-Brain Axis

The gut communicates with the brain and the brain communicates with the gut all the time. They represent a biological circuit. It is bi-directional.

Gut is not just the stomach. It includes the entire digestive tract.

The nervous system includes the brain and the spinal cord, which together make up the central nervous system. The neural retinas are also part of the Central Nervous System. The eyes are the only part of the brain that are outside the cranial vault.

Peripheral nervous system: everything that’s outside the brain, spinal cord and eyes.

Digestive system

Begins at mouth and ends in anus.

It’s a tube, and the hollow of the tube is called the lumen.

The microbiota resides all along the lumen. There are little niches where particular things can grow best.

Along the digestive tube there is a lot variation of acidity, which gives rise to different microenvironments in which microbiota can thrive or fail to thrive.

Our own behaviors will adjust the microenvironments in which the microbiota will be more likely to thrive or not.

Microbiota

Microbiota: Is the wide variety of microorganisms that live in a certain environment. So the “human microbiota” includes all bacteria, viruses, fungi, and other single-celled organisms living in the human body

They contribute to digestion. They make genes involved with digestion.

What we eat change the enzymes that these bacteria make.

They change the way that our brain functions by metabolizing some neurotransmitters. It is converted into chemicals such as GABA (suppress the action of other neurons. Its principal role is reducing neuronal excitability throughout the nervous system.).

The microbiota highly influences our immune system, brain function and digestion.

Microbiome

Microbiome: The collective genomes of the microbes (composed of bacteria, bacteriophage, fungi, protozoa and viruses) that live inside and on the human body.

What we eat strongly influences our microbiome.

But the Microbiome is also made up by things that come inside our body through breathing, thru skin contact, and also thru thoughts and social interactions.

What is a Healthy microbiome? One that includes a lot of diversity.

Probiotics and prebiotics can enhance microbiota diversity… excessive probiotics can lead to brain fog states.

Neurons in the Gut

These neurons pay attention to the components of the gut (nutrients and microbiota) and send signals to the brain so that it seeks out more of a particular food.

When we eat something we like, these neurons are activated because certain nutrients in those foods are present (sugar, fatty acids and amino acids).

Neuropod cells: These are gut sensory cells. They provide the foundation for the gut to transduce sensory signals from the intestinal milieu to the brain through fast neurotransmission onto neurons.

They have strong activation to sugars. They communicate via the pathway of the vagus nerve (responsible for the regulation of internal organ functions). When they sense sugar they send signals that trigger activation that cause us to seek more of this particular food. How? It adjusts the release of some neuromodulators (like dopamine).

What we consider the taste of a sweet food has to do with a gut sensation that is below a conscious detection (taste of food and texture are also components that determine this).

Free will & food cravings: Events in our brain are determined by biological events that are below our conscious detection.

Ghrelin

Ghrelin is famously known as the “hunger hormone”. It increases with fasting.

When fasting, ghrelin goes up and we tend to be more alert (the body is alert seeking out food). Epinephrine goes up.

Glucagon like peptide 1

GLP1 is made by neurons in the gut and in the brain. Is a hormone produced in the gut and released in response to food. It causes reduced appetite and the release of insulin.

Used to treat type 2 diabetes and to reduce obesity.

Foods that increase GLP1: yerba mate, nuts, avocados, eggs, high fiber complex grains. The ketogenic diet increases GLP1.

GLP1 is another gut-to-brain mechanism that is dependent on diet.

Mechanical signaling

When you eat a lot you might get distension of the gut. This distention is signaled and communicated to the brain to suppress the feeding. Also even vomit. Activates the area “vomit center”.

Signals are both to seek more food and also to stop eating.

Direct and indirect signaling

Direct signals: neurons in the gut communicating with neurons in the brain.

Dopamine is involved with vomiting. When dopamine is too high it makes us stop eating and even vomiting.

Indirect signals

Neurotransmitters cause the activation of other neurons. The gut microbiota are capable of influencing metabolic events and also of synthesizing neurotransmitters themselves. They make neurochemicals that can impact the body indirectly. The foods you eat, the environment of the gut microbiome can create the substrates that allow the brain to feel one way or the other.

Dopamine can be synthesized by some particular microbiota, which can raise our baselines levels of dopamine (baseline levels act as a level of the tide).

Other microbiota support the production of serotonin. Baseline levels of serotonin set our average mood. 90–95% of serotonin is produced in the gut!

Other microbiota raises GABA levels.

Studies show that creating the correct environment for these microbiota to thrive it enhances mood and wellbeing.

Early establishment of gut microbiome.

The environment that we are exposed to (contact with any mucosal lining) in the first three years of life have a profound impact on the overall menu of microbiota that we will be able to carry within our body. Building a diverse microbiome in the first three years is critical.

Cesarean delivered babies have less diverse microbiome.

The more diversity of microbiota that one can create earlier in life is essential. (Breastfed, Exposure to pets, different adults, different rooms and outside play).

If children are exposed to a lot of antibiotic treatment can be very detrimental to develop a healthy gut microbiome. And not even in children. We should be wary of antibiotics.

Gut health benefits

Particular types of microbiota (l-reuteri) can offset symptoms of autism (studies in mice) by activating the vagus nerve that stimulates dopamine and oxytocin.

Gut health also reduces obesity and diabetes.

One study showed that microbiota diversity lowers loneliness.

Tools and behaviors: DO’s and DON’ts

Stress impacts negatively the gut microbiome.

Fasting: during prolonged fasting there’s thinning of the mucosal lining and a lot of microbiota species can start to die off. So fasting can cause a disruption to certain healthy elements of the gut microbiome. Caveat: When people eat after a period of fast, there is a compensatory proliferation (increase in healthy gut microbiota).

Probiotics: ingestion of probiotics can be useful to increase microbiota diversity (at a fairly low-to-moderate level, we don’t need excessive amounts). But… after using anti biotics or being ill or super stressed, ingesting higher doses of probiotics and prebiotics can be helpful.

The bacteria that are present in most probiotics don’t actually replenish the microbiota that we need most. But they make the environment better.

Foods to Ingest

Types of food we need to ingest that enhance mood and wellbeing.

Study: they measured the impact of the microbiome health in two groups. One with a high fiber diet, and other with a high fermented foods diet.

Results: High fiber diet did not lead to increased microbiota diversity. But increased number of digestive enzymes.

However, a fair amount of fiber is a good idea, don’t neglect it.

High fermented food diet increased microbiota diversity and decrease inflammatory signals and activity.

Amount: 4 to 6 servings of fermented foods per day. Serving size: 4–6oz.

What kind of fermented foods? Low-sugar fermented foods. They have to contain live active cultures (microbiota that are alive).

When to eat them? Its going to work best if you spread the servings throughout the day. Not all in one meal.

Examples of low-sugar fermented foods:

• Plain yogurt
• Kimchi
• Sauerkraut
• Kefir
• Natto
• Brine: richness of live cultures

You can make fermented foods yourself to reduce the high costs.

Takeaway: Fermented foods are excellent for microbiome health. We should all be trying to incorporate more of these.

Artificial sweeteners

Disruption in gut microbiome (Studies only in animals).

Neurons in the gut are capable of distinguishing real sugar and artificial sweeteners.

I hope you found this useful, but I still highly recommend watching the entire episode. In the next episode Dr. Huberman is going to discuss with Justin L. Sonnenburg, the leading expert on the field. So very excited about next Monday.

Let me know if you want me to keep posting these notes! You can check out the ones that are already published as well.

You can follow me here and on Twitter to support me. This is zero-cost and ad-free content.

“Thank you for your interest in Science”