The enteric nervous system (ENS), also known as the gut nervous system or the gastrointestinal nervous system, is an important nervous system within the human body, primarily responsible for regulating and controlling the digestive system.

The enteric nervous system is a vast neural network comprising the central nervous system (including the brain and spinal cord) and the peripheral nervous system (including the nerve plexuses and nerve fibres located within the walls of the gastrointestinal tract).

Submucosal Plexus (Insular Cortex): This is a thin layer of neural tissue located within the intestinal wall, primarily responsible for transmitting sensory information such as pain, temperature and touch.

Interstitial Cortex: This is a layer of neural tissue situated between the muscles of the intestinal wall, primarily responsible for transmitting motor signals to control the contraction and relaxation of the intestine.

Subserosal Cortex: This is a layer of neural tissue located beneath the mesentery, primarily responsible for transmitting visceral sensory information, such as hunger, satiety and the urge to defecate.

The total number of neurons in the gut is roughly equivalent to that in our spinal cord, amounting to approximately 100 million.

The enteric nervous system also possesses relatively independent neural circuits; without explicit instructions from the brain, it can independently sense and respond to external stimuli, whilst controlling the digestive process. When food we consume enters the gastrointestinal tract, the enteric nervous system automatically initiates the digestive process without requiring instructions from the brain.

By sensing information from the digestive tract, the ENS is able to monitor physical and chemical changes within the gut in real time, such as pressure, temperature, humidity and the concentration of chemical substances. When the gut is affected by inflammation, infection or injury, the ENS protects it through an immune response.

At the same time, the enteric nervous system incorporates characteristics of both the sympathetic and parasympathetic nervous systems, enabling it to independently regulate gastrointestinal motility, secretion and blood circulation to ensure the digestion and absorption of food and the excretion of waste, whilst also exerting a certain influence on our heart rate, respiration and blood pressure.

This system regulates intraintestinal muscle activity and the secretion of fluids and electrolytes based on the transmission of neural signals, thereby influencing the speed and sequence of food transit.

Based on these factors, researchers believe that the enteric nervous system possesses a certain degree of autonomy; it can independently control certain digestive processes without being entirely dependent on the central nervous system, which is why it is often referred to as our ‘second brain’.

However, what many people do not realise is that the enteric nervous system is also closely linked to our emotions and psychological state. When our emotions are affected, we may experience gastrointestinal issues such as flatulence, hiccups and constipation; this phenomenon is known as the ‘gut-brain axis’.

This is why we feel particularly satisfied after eating delicious food.

On a physiological level:

The flavour compounds in food can trigger the brain to release dopamine, a neurotransmitter associated with pleasure and a sense of reward.

The release of dopamine makes people feel happy and satisfied.

At the same time, food causes blood sugar levels to rise, thereby providing the brain with the energy it needs and making a person feel energised. Furthermore, food induces a feeling of fullness, which makes people feel satisfied and comfortable whilst meeting their physiological needs.

On a psychological level:

Delicious food offers a pleasurable taste and texture experience, bringing a sense of joy.

Eating delicious food may activate areas of the brain associated with pleasure and happiness, thereby helping to relieve tension and stress and lift one’s mood.

On a socio-cultural level: Sharing delicious food is part of social interaction and can strengthen interpersonal relationships.

Although eating delicious food can bring us a strong sense of joy through physical pleasure and psychological fulfilment, it is important to note that over-reliance on food as a source of happiness may lead to health problems.

Binge-eating disorder, also known as the binge-eating subtype of anorexia nervosa, is a mental health condition associated with disordered eating behaviour. One of its defining characteristics is the consumption of large amounts of food within a short period of time, often accompanied by a sense of loss of control and an inability to stop, as well as feelings of guilt, frustration, anxiety and shame.

In addition to having a significant negative impact on physical health, binge eating disorder also has adverse effects on mental health, leading to issues such as anxiety, depression and low self-esteem.

If you or someone you know is struggling with binge eating disorder, you should advise them to seek professional medical and mental health support. Psychotherapy, nutritional counselling and medical intervention may form part of the treatment.

Therefore, whilst enjoying delicious food, it is important to maintain sensible eating habits.

Here are a few tips:

• Ensure a balanced intake of various nutrients: Combine different types of food in a sensible way to ensure a comprehensive supply of nutrients. This includes carbohydrates, protein, fat, vitamins, minerals and water.

• Diversify your food choices: Eat a wide variety of foods, including fruit, vegetables, whole grains and protein sources (such as fish, poultry, pulses and nuts), to ensure an adequate intake of all essential nutrients.

• Limit your intake of processed foods and foods high in sugar and salt: Reduce your intake of excess sugar, salt and unhealthy fats, particularly highly processed foods such as sugary drinks, fast food and sweets.

• Moderate food intake: Control your total food intake sensibly to avoid excessive consumption leading to an energy surplus.

• Eat at regular times and in appropriate portions: Maintaining regular mealtimes and portion sizes allows the body to better absorb the nutrients you consume.

• Drink plenty of water: Maintaining adequate fluid intake helps to sustain the body’s normal functions.

• Reduce or avoid alcohol and smoking: Alcohol and smoking have negative effects on health; try to minimise or avoid these habits.

• Engage in moderate exercise: Regular, moderate physical activity helps to maintain a healthy physical condition and weight.

In the enteric nervous system, dopamine and serotonin are the two most important neurotransmitters.

• The release of dopamine can influence the contraction of smooth muscle, thereby affecting the rate at which food moves through the gut.

• It can also influence the secretion of mucus, acid and enzymes in the gastrointestinal tract, thereby regulating the digestive process.

• It regulates intestinal blood flow, ensuring that the intestinal mucosa receives sufficient oxygen and nutrients.

• It modulates neuronal excitability, influences the speed of nerve signal transmission, and acts as a signal transmitter between neurons.

• It affects sensation and perception in the gut, including the perception of pain. It may influence the gut’s immune response by affecting the activity of immune cells in the gut.

The role of dopamine in the gut is complex, and its regulatory mechanisms are influenced by a variety of factors, including dietary components, neural regulation and hormonal levels within the body.

Serotonin, also known as 5-hydroxytryptamine (5-HT), is released within the intestinal wall and regulates smooth muscle contraction, thereby influencing intestinal peristalsis and motility. This is crucial for the progression and mixing of food within the digestive tract.

• It can influence appetite and satiety, thereby affecting our eating behaviour and food intake.

• It can influence the secretion of intestinal mucus, thereby protecting the intestinal mucosa.

• By influencing the activity of immune cells within the gut, it affects the intestinal immune response.

Like dopamine, serotonin also detects sensations in the gut and, in the event of intestinal inflammation, transmits this signal to the enteric nervous system. Some studies have also found that serotonin in the gut may be involved in the regulation of the cardiovascular system.

Disruption of the enteric nervous system may lead to a range of gastrointestinal problems, such as stomach pain, heartburn, bloating, constipation or diarrhoea. Certain conditions, such as irritable bowel syndrome and inflammatory bowel disease, are associated with abnormalities in the function of the enteric nervous system.