How Does the Gut Affect the Brain?

How Does the Gut Affect the Brain?

WORDS BY GENTRY SHANNON

People are what they eat! is a common catchphrase of mothers and dietitians alike. It turns out they may not be far off the mark, though saying “people think and feel what they eat” might ring a little more accurate.

The brain and spine constitute the central nervous system (CNS) and are the body’s control center for nearly all daily tasks. However, as scientists study the relationship between the gut and the brain, it’s becoming increasingly clear that the CNS is not the only controlling factor in digestion and emotions.

THE ENTERIC NERVOUS SYSTEM

Enteric Nervous System (ENS) is located in the lining of the gastrointestinal system and functions to control elements of digestion such as motor function, blood flow and immune and hormonal responses. The ENS can act independently and is so powerful that it is sometimes referred to as a second brain, though it usually collaborates with the CNS. This network of more than 100 million neurons uses 30 neurotransmitters to send signals and continue its regulatory work.

Because the ENS is located throughout the gastrointestinal tract, the health of the gut microbiome directly impacts ENS functions.

Located in the large intestine is an area called the cecum, home to over a thousand different types of bacteria, viruses and fungi. These microbes constitute the gut microbiome. As people age and are exposed to new foods and environments, experience hormonal changes and sometimes suffer gut complications, the diversity and overall health of this gut microbiome fluctuate.

THE “GUT-BRAIN AXIS”

Although the ENS can act independently of the central nervous system, it is also inextricably connected to the CNS. This is because the ENS relies on neurotransmitters, just as the CNS does. Roughly 50% of the body’s dopamine and 90% of its serotonin originates in the gut. This collaboration between the ENS and CNS is known as the “gut-brain axis.”

For years, doctors considered the relationship between the gut and brain to flow in only one direction. For example, they knew that mental troubles such as anxiety and depression affected gut health disorders, such as IBS (irritable bowel syndrome), a common affliction of the large intestine that results in diarrhea, bloating and abdominal pain.

However, recent research indicates that the gut-brain axis may flow both ways: imbalances in the gut adversely affect the ENS, which has negative consequences for the brain. In addition, the gut microbiome imbalance associated with IBS has been linked to emotional fluctuations, even to the point where some victims of IBS develop mental disorders.

On a simpler and more observable level, the average person likely experiences the gut-brain axis on a daily basis. For instance, those who dislike public speaking may be familiar with mild gut discomfort in the moments before taking a stage, often called “stomach butterflies.” In more extreme cases, the mental strain of presenting to a crowd may even trigger diarrhea. Both of these are examples of the connection between the CNS and ENS.

ROUGHLY 50% OF THE BODY’S DOPAMINE AND 90% OF ITS SEROTONIN ORIGINATES IN THE GUT. THIS COLLABORATION BETWEEN THE ENS AND CNS IS KNOWN AS THE “GUT-BRAIN AXIS."

AN ALTERED MEDICAL OUTLOOK AND APPROACH

Now that doctors have established a connection between gastrointestinal health and mental well-being, the medical approach to treating both is undergoing substantial changes, taking on a more holistic and integrative approach.

According to Johns Hopkins Medicine, a thorough comprehension of the gut-brain axis allows doctors to more successfully treat bowel disorders through CNS-centered medications and regimens such as antidepressants, cognitive behavioral therapy (CBT) and medical hypnotherapy. For example, some antidepressants may combat symptoms of IBS by soothing ENS nerves situated in the gastrointestinal tract.

MAINTAINING A HEALTHY GUT

To ensure a high-functioning ENS, thereby protecting the well-being of CNS actors such as the brain, it is important to maintain a healthy gut microbiome. Here’s the good news: a medical degree is not necessary to protect one’s gut-brain axis! Here are two recommendations that are easy to implement:

1. Eat Well: A healthy and balanced diet results in a balanced gut microbiome. Drinking lots of water and eating fiber-rich foods and probiotics will help you maintain that balance. Likewise, avoid overly fatty or processed foods.

2. Move Regularly: Daily exercise positively impacts your health for several reasons, gut health among them. There is no need to run a half-marathon - even something as simple as taking10,000 steps a day can increase blood flow to the gut and promote fluid digestion.

THE FIRST LINE OF DEFENSE FOR THE GUT-BRAIN AXIS IS A CONSISTENT AND HEALTHY LIFESTYLE.

The human body is a complex machine composed of interconnected systems that impact others’ functions. Thanks to recent scientific advances, the relationship between the gut and brain is becoming increasingly clear, allowing doctors to take a more prosperous and holistic medical approach. But remember, the first line of defense for the gut-brain axis is a consistent and healthy lifestyle; eat well and regularly move to protect your ENS and CNS!