There are more neural pathways in the gut than the brain: the surprising science behind the "Second Brain”

Did you know your gut has a nervous system so complex it's often referred to as the second brain?

The digestive tract contains 100–500 million neurons that are in constant communication with the brain- crazy right?

Recent research has revealed that this gut-brain connection influences not just digestion but also mood, mental health, and decision-making. In this post, we’ll explore how this connection works, why it matters, and how you can optimize your gut health to enhance brain function.

The Enteric Nervous System: The Brains Behind Your Gut

The enteric nervous system (ENS) is a vast network of neurons within the digestive tract. It controls essential gut functions such as:

• Gastric acid secretion
• Gut hormone release
• Immune system regulation
• Gastrointestinal movement

Containing more neurons than the spinal cord, the ENS is often called the "second brain" because it can function separately of the central nervous system. One of its primary communication pathways is the vagus nerve, one of the longest nerves in the body, stretching all the way from the brain to the abdomen. This nerve plays a crucial role in transmitting signals between the gut and brain, influencing everything from your mood to your stress levels.

The Gut Microbiome: Small but Mighty

Your gut microbiome consists of trillions of bacteria, fungi, and viruses, most of which reside in the large intestine. These microbes play a critical role in:

• Digestion & nutrient absorption
• Immune system support
• Mental health & cognitive function

Interestingly, everyone’s gut microbiome is unique, shaped by diet, genetics, environment, and lifestyle. A well-balanced microbiome (a good mix of different types of bacteria and other other tiny organisms in your digestive system) contributes to overall well-being, while an imbalance (dysbiosis) can lead to digestive issues, inflammation, and even mental health disorders.

Why Your Gut’s Neural Networks Matter

Although the brain has more neurons, the gut has a huge network of pathways constantly transmitting signals. This means the gut is not just for digestion—it acts like a "second brain," and can affect your:

1. Mood and Emotional Well-Being

Did you know 90% of serotonin (the “happy” neurotransmitter) is produced in the gut?specialised cells in the lining of the gut called enterochromaffin cells interact with gut bacteria to regulate serotonin production. When gut bacteria are imbalanced, serotonin production can be disrupted, potentially leading to mood disorders like anxiety and depression.

2. Stress Resilience

The gut microbiome plays a key role in regulating the hypothalamic-pituitary-adrenal (HPA) axis, which controls the body’s stress response. Certain gut bacteria produce GABA and dopamine, neurotransmitters that help regulate anxiety and stress. A healthy gut microbiome helps to increase your stress resilience, while chronic stress can disrupt gut bacteria, increase inflammation, and elevate cortisol levels (the stress hormone).

3. Cognitive Function & Decision-Making

The vagus nerve sends signals from the gut to the brain, affecting decision-making and mental clarity. Gut bacteria also produce short-chain fatty acids (SCFAs), which help reduce brain inflammation and support cognitive function. A balanced microbiome has been linked to better focus, problem-solving abilities, and mental clarity.

How to Improve Your Gut-Brain Connection

1. Increase Gut Microbial Diversity

A diverse gut microbiome is key to overall health. Probiotic foods introduce beneficial bacteria, increasing microbiome diversity. Here are some examples of probiotic foods:

• Kefir & natural yogurt
• Kombucha (fermented fruit drinks)
• Kimchi, sauerkraut, miso (fermented vegetables)
• Tempeh (fermented soy)

A fiber-rich diet also supports beneficial gut bacteria. Eating a wide variety of plants ensures you're feeding different types of bacteria. Focus on have a range of soluble, insoluble, and resistant starch fibres, such as:

• Vegetables,
• Legumes, 
• Whole grains
• Fruits

You should try to aim for 30 different plants a week, although this sounds daunting at first, they do add up! Remember this isn't just vegetables and fruits, nut milks, whole grain rice and pastas and beans all count!

2. Feed Your Good Bacteria with Prebiotics

Prebiotics act as food for the good bacteria in our guts. Some examples are: 

• Asparagus
• Bananas
• Onions & garlic
• Oats & leeks

3. Reduce Processed Foods & Sugar

Processed foods often lack fiber and contain artificial sweeteners, trans fats, and additives that can disrupt gut bacteria. Try these whole food swaps:

• Sugary cereals → Oatmeal with fruit
• White bread → Whole grain bread
• Flavored yogurt → Kefir or plain Greek yogurt
• Fizzy drinks → Sparkling water or kombucha
• Processed meats → Whole protein sources (chicken, fish, tofu, beans)
• Sweets → Dark chocolate, dates, Dung balls

4. Manage Stress to Support Gut Health

Since stress affects gut health, incorporating stress management techniques can improve the gut-brain connection. Try:

• Deep breathing & meditation
• Daily movement (even a 30-minute walk in nature can lower cortisol by 20%)
• Cold exposure (cold showers activate the vagus nerve)
• Singing or humming (stimulates the vagus nerve for relaxation)

The Future of Gut-Brain Science

As research advances, microbiome-based therapies could revolutionize mental health care. Instead of relying solely on psychiatric medications, targeting the gut may offer a natural, long-term solution for mood disorders.

Could healing the gut be the key to unlocking better mental health? If so, the future of mental health treatment may lie in something as simple as the food we eat and the bacteria that live within us.

Final thoughts 

The gut is more than just a digestive organ—it's a neural powerhouse that affects everything from mood to memory. Start by taking small steps to improve you gut health, from switching your normal sugary breakfast cereal to a gut loving bowl of porridge or taking a short walk on your lunch break to lower your stress levels.The missing key to optimal brain function might just be within your gut!