The Secret of Serotonin and Gut Health

Written by Chelsea Cleary, RDN
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and Medically Reviewed by Julie Guider, M.D.
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Serotonin is a neurotransmitter found in the brain and gut, an important factor of your gut health. It plays a role in mood, sleep, appetite, pain perception, and gastrointestinal function.

Serotonin is a key player in our body’s ability to regulate our emotions and behavior. Low levels of serotonin are linked to depression, anxiety, obsessive compulsive disorder (OCD), and other mental health disorders.

A healthy gut microbiome helps produce serotonin, which regulates our mood and behavior. This means that a balanced gut microbiome is essential for good mental health.

This article will get into the brain-gut connection, and how it affects health, mood, and everything else. What are the ingredients that make up a healthy digestive system?

The answers lie within your belly…

Table of Contents show

Digestive Diseases & Disorders

The list of ailments linked to a malfunctioning digestive system is long and varied. It includes:

If you think you might have a digestive disorder, you should learn how the digestive system functions so you can figure out how to minimize its effects or even eliminate it altogether.

Understanding Digestion

Digestive Enzymes

Digestion begins in your mouth as saliva helps break down the carbohydrates and fats in your food. Chewing starts the production of digestive enzymes in your stomach. Mucosa in the mouth, stomach, and small intestine contain tiny glands that produce juices to help digest food.

In the digestive tract, a smooth muscle layer helps break down food and move it along the tract. Most of the food absorption process takes place in the small intestine.

The additional enzymes produced by the intestinal linings break down fats, carbohydrates, and proteins. Your liver produces bile to aid in fat absorption.

The end result of this entire process of digestion is that food becomes sugars, fats, and proteins that can enter the bloodstream and provide the energy that your body needs. Once the nutrients have been absorbed, the remaining waste products wait in the colon for expulsion in the form of stool (bowel movements).

Hydrochloric Acid (HCl)

Digestive enzymes aren’t the only substance a body needs to process food. The stomach needs a mixture of hydrochloric acid and digestive enzymes to break down food into nutrients. Pepsin – an enzyme produced by the body – requires an extremely acidic environment in order for it to function well.

As we age, a variety of factors can catch up with us, and result in low stomach acid (low levels of HCl). That includes over-use of medications and poor diet.

Without an adequate amount of stomach acid, the digestion of protein, carbohydrates, and fat cannot be properly completed.

The stomach requires acid for protection against bacterial and fungal overgrowth (they cannot thrive in an acidic environment). Acid also helps the body to absorb essential vitamins and minerals properly.

Intestinal Flora

Also referred to as gut flora, bacteria, microflora, and probiotics, intestinal flora plays a vital role in the fermentation and digestion of carbohydrates, and aids in the digestion of proteins and fats.

Bacteria populations that live in the gut are a combination of both good and bad bacteria. A balance between good and bad bacteria is necessary for an optimal state of health. They help with digestion, metabolism, detoxification, and having balanced immunological responses to potential allergens.

Bad bacteria include those that cause diseases such as Clostridium, Salmonella, and others. They become a problem when their numbers grow larger than the number of good bacteria. Even yeast, such as Candida, are healthy in small amounts. Read more about Candida and IBS.

Good bacteria include Bifidobacterium bifidum, Lactobacillus acidophilus, Lactobacillus bulgaricus, and others. Good bacteria can be taken as a probiotic supplement. They help us maintain a healthy gut, digest food, provide us with nutrients and vitamins, and fight off the bad bacteria. 

Good gut flora helps keep intestinal acidity at a normal pH level. They produce certain vitamins, deprive unwanted bacteria of nutrients, secrete acids that bad bacterial have trouble dealing with, and prevent disease by depriving pathogens of nutrients.

Serotonin: The Brain-Gut Connection

The digestive system plays a vital role in the production of serotonin – the body’s natural “feel good hormone”.

Over 95% of the body’s serotonin is found in the gastrointestinal tract (GI tract), which has been called the “second brain” because of its role in producing serotonin and so many of the body’s vital functions. In fact, serotonin has been linked to everything from autism to constipation.

Serotonin is a major player in the function of our digestive system, causing the contraction of the intestine and triggering the nerves that signal pain, nausea, etc.

The vagus nerve is the major nerve that connects the brain to the gut. Improve gut health by activating the vagus nerve.

It also affects the functioning of the cardiovascular, immune, and renal systems. This amazing hormone regulates aggression, mood, appetite, cognition, sexual behavior, and even sleep.

Serotonin is a chemical produced in our bodies from the protein tryptophan, an amino acid derived from foods we eat.

Diet, then, affects not only the state of your digestive system and overall physical well-being, but it also has a profound influence on your memory, mental clarity, and mood; these functions are all controlled by serotonin.

Optimal nutrition and digestive health is crucial to the production of serotonin and that, then, plays an important role in everything from our mental health to our ability to fall asleep at night.

Diet Is Vital to Serotonin Production

Food Combining for Better Digestion

Nutrition is essential to both our physical and mental well-being. It’s also essential to a healthy digestive system that produces enough serotonin.

A diet that’s rich in organic fruits and vegetables, and free of trans fats, refined wheat and sugar will go a long way to help to prevent the build up of toxins in the colon.

When it comes to serotonin production, the importance of raw foods for their nutritional value and serotonin-boosting properties cannot be overstated.

Tips for Ensuring Adequate Serotonin Levels

  • Eating foods rich in calcium, mag­nesium, and vitamin B6 can help with serotonin production.
  • If you cannot get fresh, organic fruits and vegetables, go with frozen over canned.
  • Omega-3, omega-6, and gamma-linolenic acid (GLA) are required for good serotonin production. 
  • Healthy carbohydrates and proteins can help metabolize foods high on the list of ingredients responsible for producing serotonin.
  • Avoid white flour and sugar carbohydrates, like refined sugar in candy. They provide a temporary boost in serotonin levels, which is quickly followed by a crash.
  • Foods that contain completely formed serotonin include bananas, kiwis, pineapples, plantains, plums, tomatoes, and walnuts.
  • Foods rich in tryptophan include almonds, bananas, beans, cheeses (especially Cheddar and Swiss), chicken, eggs, fish (particularly high-oil fish such as herring, mackerel, salmon, sardines, and tuna), milk, peanuts, soy foods, turkey, and yogurt.
  • Digestive enzymes and probiotic supplements can help full nutrient absorption from the foods listed, resulting in an overall increased nutrient intake.

How to Increase Serotonin Levels Up

Digestion affects nearly everything we do. From appetite to immune system health, a healthy digestive system with good serotonin production can mean the difference between feeling well and feeling lousy.

As people age, they often find more issues with their GI tract, sometimes leading to uncomfortable GI disorders. A lack of clarity, memory problems, and moodiness are some of the accompanying complaints.

Maintaining high serotonin levels will help keep your spirits up, and lowers the risk of developing a digestive disorder. Here are our top 4 tips on how to keep your serotonin levels up.

1. Keep Your Colon Moving

Cleansing the digestive tract is a good way to deal with digestive disruptions. Maintain a balanced diet that’s high in fiber, to help keep your bowel movements regular. This will help balance the good and bad bacteria present in your body.

2. Take A Multivitamin

Since it’s nearly impossible to get the daily nutrition we need from the food that we eat (especially with a typical American diet), vitamin supplements are critical.

There is no better thing you can do to improve your digestive and overall health than to support your digestive system by taking a daily multivitamin.

A multivitamin helps provide you with the nutrients to support the metabolic processes that occur within the digestive tract. Increasing your nutrient intake also helps increase serotonin production.

Can You Take Prebiotics and Probiotics Together?

3. Take a Digestive Enzyme with Every Meal

To really focus on improving your digestive system, take a digestive enzyme supplement to help maximize the production of serotonin.

Digestive enzymes help to break down sugars, leaving little left over for bad bacteria to munch on. An enzyme boost can maximize nutrient absorption and, by extension, increase serotonin levels.

4. Pass the Probiotics, Please

With the above information about the differences between good and bad bacteria, the importance of probiotics is even clearer.

Probiotics will help with absorption of nutrients, which leads to higher serotonin levels, which leads to healthier guts. 

5. Antidepressant Prescription

If all else fails, consider trying medication to treat depression or anxiety. The antidepressant prescription will not only help with depression but will also increase serotonin levels.

Selective serotonin reuptake inhibitor (SSRI) is a common group of drugs used to treat depression. These medications work by blocking the reabsorption of serotonin back into the nerve cells. SSRIs have been shown to restore serotonin levels in the brain, helping to relieve symptoms of depression.

Serotonin Final Thoughts

Your digestive system can rightly be called a “brain.” The essence “you” depends on what you eat and your ability to gain benefits from what you consume. Just how connected is the brain and gut?

More and more research shows that the health of the digestive system is what influences numerous diseases, including those never previously thought of as originating in our guts — such as depression and other mental illnesses.

Learn more about gut health with these articles: 

Written and Medically Reviewed By

  • Chelsea Cleary, Registered Dietician Nutritionist (RDN)

    Chelsea is a Registered Dietitian Nutritionist (RDN) specializing in holistic treatment for chronic digestive disorders such as Irritable Bowel Syndrome (IBS), SIBO, and Crohn’s disease. She educates patients on how they can heal themselves from their conditions by modifying lifestyle and dietary habits.

  • Julie Guider, M.D.

    Dr. Julie Guider earned her medical degree from Louisiana State University School of Medicine. She completed residency in internal medicine at the University of Virginia. She completed her general gastroenterology and advanced endoscopy fellowships at University of Texas-Houston. She is a member of several national GI societies including the AGA, ACG, and ASGE as well as state and local medical societies.

    Gastroenterologist, M.D.