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Digestive Health

How your gastrointestinal system keeps you healthy.

Your gastrointestinal (G.I.) system, the key player in your overall digestive health, is one of the most important systems in your body. It consists of the mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, and gallbladder, and is responsible for breaking down food so that it can be absorbed and used by the body (including the heart and brain, two of your most vital organs). Your digestive health can be affected by so many variables—diet, exercise, lifestyle, and health conditions, among other factors.

In order to understand how to nurture your digestive health, it helps to first understand what the digestive system looks like and how it functions. Ahead, we’ll dive into the details of how your digestive system works, common health conditions and diseases that affect the digestive tract, and how to improve your digestive health.

Your digestive health is important to regulate many functions in your body. Amanda K Bailey

How does the digestive system work?

According to the National Institutes of Diabetes and Digestive and Kidney Disease (NIDDK), your digestive tract is broken down into six main hollow organs and two solid ones that help ingest, digest, absorb, and eliminate food as it moves through the tract. Let’s start at the top:


When you take your first delectable bite of that fresh pasta or homemade pie, you’re likely only thinking about how awesome it tastes. While you’re preoccupied with all the flavors, your mouth is already started to digest the food. Using your tongue and teeth, you begin to digest your food by chewing it. As you chew, your salivary glands release saliva, which has chemicals that begin the initial breakdown of food. Swallowing the food pushes it into your esophagus through your throat, which begins the next stage of digestion.


After you’ve chewed and swallowed that first bite, your mind has already moved on to the next bite. But your food continues its journey. Once it enters your esophagus, it is moved through the tube by peristalsis. You can think of peristalsis as an almost “squeezing” motion that the muscles in your digestive system do in order to push and mix food and liquid within the tract. Once the food reaches the bottom of your esophagus, your lower esophageal sphincter, a ring-like bundle of muscle, relaxes to allow the food to enter your stomach.


The party really starts when food hits your stomach. In your stomach, food and liquid are mixed with digestive juices—including highly acidic hydrochloric acid (stomach acid) and various enzymes, among other compounds—that continue to break down food. As food mixes with the digestive juices, it forms a mass called chyme, which then enters your small intestine from your stomach.1

Small intestine

Once food enters your small intestine, the solid organs of your digestive tract—including your liver and pancreas—help break down the food even further. Pancreatic enzymes secreted by your pancreas help break down carbohydrates, fats, and proteins, while bile secreted by your liver assists in the breakdown of fats and vitamins. All of these nutrients are absorbed into your bloodstream from the walls of your small intestine, leaving behind waste products (yes, the makings of poop) that are then moved into your large intestine.

Large intestine

When waste products enter your large intestine, they form a solid waste product called stool (still just poop). The large intestine's primary job is to regulate the water content in creating stool, both by absorbing and secreting it. Stool continues the journey through your large intestine via peristalsis, and eventually reaches your rectum and your anus, triggering a bowel movement.


When you’re not eating, your body doesn’t need to use the bile created by your liver, so it’s stored in your gallbladder. Once the digestive process begins again, your gallbladder will send this stored bile through specialized ducts directly into your small intestines to help break down food.

The two solid organs

In addition to the five main organs of your digestive tract, there are two solid organs that also play a supportive role in breaking down food, according to the NIDDK:

  • Liver: Your liver is a large organ situated in the upper right portion of the abdomen that performs many functions inside of your body. As part of the digestive system, it creates a liquid called bile, which is sent to your small intestine to help break down fats and vitamins. When bile is not in use, it is sent to your gallbladder for storage. The liver also stores glucose (sugar)—what your body uses for energy—and nutrients for later use.
  • Pancreas: During digestion, your pancreas creates a specialized mixture of enzymes that are sent to your small intestine to help break food into various nutrients, such as carbohydrates, fats, and proteins. Outside of digestion, your pancreas is also responsible for creating the hormone insulin, which helps your cells recognize and absorb energy-producing glucose from the bloodstream.

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What are some of the most common digestive conditions?

A healthy digestive system should do a great job of adequately breaking down food into the nutrients your body needs to thrive, but sometimes problems can arise. According to the NIDDK, digestive diseases and conditions can be both short-term and long-term issues, and can affect all areas of the digestive tract.

Below, you’ll find a quick intro to common digestive diseases:

Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) isn’t a set condition so much as it is a handful of symptoms that include chronic abdominal pain and changes in bowel movements. There are three primary types of IBS: IBS with diarrhea (IBS-D), IBS with constipation (IBS-C), and mixed IBS with both diarrhea and constipation (IBS-M). Because IBS doesn’t cause any visible damage to the digestive tract, it is generally only diagnosed after other conditions have been ruled out.2

Inflammatory bowel disease (IBD)

Inflammatory bowel disease (IBD) is an umbrella term for three specific gastrointestinal autoimmune diseases—Crohn’s disease, ulcerative colitis, and microscopic colitis. Although the three conditions differ in where they occur and how they affect the body, they all result in inflammation of the digestive tract.3

  • Crohn’s disease is a chronic inflammatory disease that causes severe inflammation of the digestive tract. Abdominal pain, frequent diarrhea, and unintentional weight loss are among the common symptoms of the condition, according to the NIDDK. However, in untreated Crohn’s disease, people may also experience other symptoms such as fever, fatigue, joint pain, and other side effects of inflammation and malnutrition.
  • Ulcerative colitis is another chronic condition that causes inflammation in the lower portion of the digestive tract, including the large intestine and the rectum (the area right before your anus). Ulcerative colitis that affects the entire large intestine is called pancolitis, while ulcerative proctitis affects only the rectum. Abdominal pain, diarrhea, and seeing blood in the stool are some of the symptoms someone with ulcerative colitis might experience, per the NIDDK.
  • Microscopic colitis: This is another type of IBD that involves chronic inflammation in the colon. The main symptom is watery—but not bloody—diarrhea. It’s important to know that the colon may not appear inflamed, as it does with Crohn’s and ulcerative colitis, so a biopsy—a small piece of tissue that is examined in the lab—is an important step for diagnosis.

Celiac disease

Celiac disease is an especially tough condition for bread lovers. That’s because it’s a chronic autoimmune digestive condition that is caused by an actual allergy to gluten, a protein found in wheat, rye, barley, and any products containing these ingredients. When someone with celiac disease ingests gluten, their immune system attacks the small intestine leading to painful symptoms and damage to that area. Symptoms typically include bloating, diarrhea, constipation, nausea, vomiting, loose stools, and abdominal pain following the ingestion of gluten. Untreated celiac disease can even lead to nutrient deficiencies, which can affect the entire body—not just the digestive tract.4


Diverticulosis is a digestive condition that causes small pouches, called diverticula, to form along the lining of the large intestine. Because these pouches bulge outwards, they can cause pain, bleeding, and even infections inside of the digestive tract. Diverticulosis often has no symptoms, but if you do experience them,  bloating, constipation, and lower abdominal pain are the most common—although other symptoms may appear if the diverticula become inflamed or infected. That’s called diverticulitis and can cause symptoms like severe abdominal pain that gets worse over time, diarrhea, nausea, constipation, and fever.5

Acid reflux

Acid reflux, also called gastroesophageal reflux (GER), can happen when the contents of the stomach escape and re-enter the esophagus. Generally, acid reflux happens when the lower esophageal sphincter becomes weak or relaxed, which can allow undigested or partially digested food and stomach acid to travel back up the esophagus, according to the NIDDK. Common symptoms include heartburn—you know, the feeling of a thousand suns in your chest—chest pain, regurgitation, and nausea. When acid reflux becomes a more severe, frequent, and long-term issue, it’s considered gastroesophageal reflux disease (GERD). Complications can potentially include inflammation of the esophagus, ulcers, and precancerous changes.


You might know this better as the good old “stomach flu.” Probably well-acquainted, right? Gastroenteritis is just the fancy name for an intestinal infection that can be caused by any number of viruses or bacteria. Foodborne illness, or food poisoning, is a type of bacterial gastroenteritis that is specifically caused by bacteria from eating contaminated food. Gastroenteritis commonly causes abdominal pain, diarrhea, nausea, vomiting, and occasionally fever, but you probably already knew that.6


While this sounds similar to gastroenteritis, gastritis is a condition in which the lining—or mucosa—of the stomach becomes inflamed for whatever reason. Gastritis can be triggered by a variety of underlying causes, such as infections and autoimmune conditions, but is commonly caused by an infection from a bacteria called Helicobacter pylori (H. pylori), according to the NIDDK. Symptoms of gastritis include abdominal pain or discomfort, nausea, vomiting, fullness, loss of appetite, and weight loss. If the stomach lining has been damaged, but there is little to no inflammation, it’s called gastropathy, and the symptoms are generally the same as gastritis.

Lactose intolerance

If you’re a dairy lover who gets farty when they eat cheese (raises hand), take note. Lactose intolerance is a digestive condition in which a person is unable to digest lactose, which is a sugar that is present in milk and milk-containing products. It’s different from a true dairy allergy, where your body has an immune reaction to a protein in milk and dairy. This sets off allergy symptoms like swelling of the face, wheezing, hives, vomiting, and diarrhea. A life-threatening reaction called anaphylaxis can occur with a dairy allergy.

On the other hand, when someone with lactose intolerance consumes lactose, they may experience a variety of uncomfortable symptoms (but they are not life-threatening), including abdominal pain, bloating, gas, and diarrhea. Symptoms generally vary depending on how much of that cookies and cream ice cream you consumed.7

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What are the most common symptoms of digestive health issues?

It’s relatively normal for most people to experience uncomfortable digestive symptoms after eating certain foods. For example, spicy wings can trigger a bout of acid reflux, just like a high fiber bran muffin can cause gas and discomfort. However, there are some acute and chronic symptoms that may point to a larger digestive health issue that potentially needs treatment.

While it’s not always an emergency, it’s a good idea to schedule a visit with your doctor if you are experiencing persistent symptoms of:

  • Abdominal pain
  • Bloating
  • Discomfort
  • Diarrhea
  • Constipation
  • Nausea
  • Vomiting

When severe digestive symptoms develop suddenly—meaning you felt fine and then all of a sudden experience severe discomfort or pain—it can indicate one of several life-threatening conditions that need immediate treatment. If you are experiencing any of the following symptoms, seek medical attention immediately, per Oxford Medicine:

  • Severe abdominal pain
  • Severe bloating
  • Diarrhea or vomiting that lasts for days
  • Blood in your stool or vomit
  • Bright red, dark red, or black stool
  • Jaundice, or yellowing of the skin

Depending on your symptoms, your doctor will likely perform a physical exam and run diagnostic tests—such as blood tests and imaging tests—to determine the underlying cause of your symptoms.

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How are digestive issues diagnosed?

Digestive diseases are generally diagnosed using tests that can look for functional issues, damage to the digestive tract, and other signs of potential disease. If your whole body tenses up when you hear the word “colonoscopy,” just know that it—and these others tests—are pretty painless procedures that your gastroenterologist does all the time. According to the NIDDK, the following tests can be used to diagnose most digestive diseases:

  • Upper gastrointestinal (GI) series: This is also called a barium enema. Your doctor will use X-rays, video imaging, and liquid barium—a substance that can be seen on x-rays—to view your upper digestive tract and identify any issues that may be present.
  • Upper gastrointestinal (GI) endoscopy: This procedure involves a specialized camera called an endoscope to view the inside of your upper GI tract.
  • Lower gastrointestinal (GI) series: A lower GI series utilizes a series of X-rays to identify and diagnose issues within your large intestine.
  • Endoscopic retrograde cholangiopancreatography (ERCP): This is used to specifically diagnose and treat issues within your bile and pancreatic ducts. Magnetic resonance cholangiopancreatography (MRCP) can also be used to diagnose these problems.
  • Flexible sigmoidoscopy: This can be used to identify issues that may be affecting the lower portion of your colon—called the sigmoid colon—and your rectum. Your doctor can find inflamed tissue, polyps, and even colon or rectal cancer.
  • Colonoscopy: This can be used to screen for colon polyps and cancer, and check for bleeding and other causes of digestive symptoms. It’s usually performed under sedation, and your doctor will use a tool called a colonoscope to look inside your rectum and colon.8
  • Virtual colonoscopy: This is an alternative to a regular colonoscopy in which a computer is used to create images of your rectum and colon, rather than a scope. It may not be as accurate as a regular colonoscopy at finding abnormalities within the tract.
  • Lab tests: Blood tests can check for autoimmune conditions, nutritional deficiencies, and other blood cell abnormalities. A stool culture and fecal occult blood test can also be used to analyze the stool for non-visible signs of disease, such as blood.

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How to improve gut health

One of the most important things you can do for your body is to take care of your gut—something that can be done with mindful steps in your everyday life. Below, we’ll share five science-backed tips for how to improve your gut health, one small step at a time.

1. Eat your probiotics (and prebiotics).

Your gut microbiome consists of—wait for it—trillions of microorganisms all working together to support everything from your digestive health to your immune health, and so much more. One of the ways that you can support this microbiome is by eating beneficial microorganisms called probiotics, according to the Harvard School of Public Health. You can increase your probiotic intake by eating more probiotic-containing foods, like Greek yogurt, kefir, sauerkraut, kimchi, and other fermented foods.

Prebiotics play an important role in keeping your gut microbiome healthy, too. Unlike probiotics, prebiotics are not live organisms—they are the food that those live microorganisms eat, so they can influence the type of microorganisms that thrive in your gut. According to a 2017 Study published in Nutrients,9 most prebiotics can be found directly in your diet, from fiber-rich foods such as bananas, berries, artichokes, asparagus, wheat, oats, and more.

2. Keep your body hydrated.

Aside from quenching your thirst and generally keeping your body running, water is necessary for the transportation and breakdown of food inside your digestive tract and the healthy transport of stool as it leaves your body. Research has also shown that water intake can actually influence the diversity of your gut microbiome, too, so make sure that you’re drinking enough water for your body each day.10

3. Prioritize getting enough sleep.

It’s no secret that sleep is important to your health. In fact, a lack of sleep can increase stress levels, impact hormone levels, and even affect the way you choose to eat—all of which can potentially impact your gut health. Also, 2015 research published in the journal Gastroenterology and Hepatology suggests that there is a connection between sleep disorders and gastrointestinal diseases, which highlights the importance of making sure that you’re getting enough shuteye (try to aim for seven to eight hours per night!).11

4. Move your body more often if you can.

You might not think that exercise has anything to do with gut health, but 2017 research published in the journal Oxidative Medicine and Cellular Longevity suggests it does. The study found that exercise can not only increase blood flow to your gut but also help food and stool move through your digestive tract.12 In addition, regular exercise seems to have a beneficial impact on the diversity of your gut microbiome, so try to move your body for at least 150 minutes a week, as recommended by the Centers for Disease Control and Prevention (CDC).

5. Practice reducing your stress

We all know stress isn’t good for your mental health, but chronic stress may actually increase your risk for chronic diseases. According to Harvard Health, hormones released during the fight-or-flight response can slow down or halt digestion, which may lead to chronic digestive symptoms and problems. Consider adding activities like gentle exercise, mindfulness, and relaxation techniques into your daily or weekly routine to help manage and reduce your stress levels.

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When to see a gastroenterologist

If you’ve been experiencing acute or chronic G.I. symptoms such as abdominal pain, bloating, diarrhea, constipation, or other uncomfortable symptoms, it’s time to schedule a visit with your primary care doctor if you have one. During your visit, your doctor will help review your symptoms and refer you to a gastroenterologist (a doctor who specializes in all things digestive health), if needed. And don’t be afraid to be honest—they’ve certainly seen it all when it comes to G.I. issues and only want to help you feel better as soon as possible.

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  1. StatPearls, Physiology, Gastrointestinal
  2. World Journal of Gastroenterology, Irritable Bowel Syndrome: Pathogenesis, Diagnosis, Treatment, and Evidence-Based Medicine
  3. StatPearls, Inflammatory Bowel Disease
  4. BMC Medicine, Celiac Disease: A Comprehensive Current Review
  5. Gut and Liver, Diverticular Disease: An Update on Pathogenesis and Management
  6. StatPearls, Viral Gastroenteritis
  7. StatPearls, Lactose Intolerance
  8. StatPearls, Colonoscopy
  9. Nutrients, Effects of Probiotics, Prebiotics, and Synbiotics on Human Health
  10. The Journal of Nutrition, Drinking Water Source and Intake Are Associated with Distinct Gut Microbiota Signatures in US and UK Populations
  11. Gastroenterology and Hepatology, Sleep Dysfunction and Gastrointestinal Diseases
  12. Oxidative Medicine and Cellular Longevity, Exercise Modifies the Gut Microbiota With Positive Health Effects

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