Do You Know How Your Food Gets Turned Into Poop?

Analysis by Dr. Joseph Mercola Fact Checked

how digestive system works

Story at-a-glance

  • What starts out as your dinner ends up in the toilet bowl many hours later; beginning in your mouth, food travels through your stomach and intestines, interacting with enzymes and bacteria to remove nutrients, produce vitamins and eventually a final waste product
  • Your stomach churns the food with acid, your liver and pancreas produce enzymes to break down the food and your intestines are the setting where nutrients are extracted; bacteria in your intestines use fiber to thrive and help produce vitamins, such as biotin, folate and thiamine
  • Digestion of your food occurs outside the internal workings of your body; imagine your body is a cylinder with a tube running from top to bottom. That which is inside the tube does not interact with the sterile environment in your body
  • Consider making small changes to improve your elimination health, such as keeping an elimination routine, staying hydrated, eating 25 to 50 grams of fiber for every 1,000 calories, and squatting while having a bowel movement

WARNING!

This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.

Your gastrointestinal tract is home to millions of bacteria, some beneficial and others harmful. These bacteria are important to your overall health. Understanding how your body processes food and eventually eliminates waste may motivate you to make changes in your diet, ultimately improving your health.

Constipation is an uncomfortable and sometimes painful challenge. In some instances, stool can got stuck in your intestines causing a blockage. What constitutes a healthy evacuation schedule is impacted by several factors.

You may have questions, such as how much is too little or too much? What affects how often you go? And perhaps the most important question may be: What can you do to become more regular?

The process of elimination is your body's way of getting rid of undigested food and waste products. Doing this regularly positively affects your emotional state, how well your brain processes information and even reduces skin breakouts and bloating.

The size, shape and color of your bowel movements can also tell you a lot about your health. The appearance and frequency gives you clues about the health of your gastrointestinal tract and may give you an early signal of disease processes, such as digestive problems and even cancer.

Digestion Occurs Outside the Body

Before delving into the mechanics of how food is digested and small strategies that reap big rewards to improving your health, it's important to remember your digestive tract actually resides outside of your body.

Imagine your body is a cylinder. If you were to run a tube directly through the center of the cylinder from top to bottom, this would represent your gastrointestinal tract. The solid part of the cylinder around the tube represents the inside of your body.

Your gastrointestinal tract is full of bacteria that must remain separate from your sterile internal organs. When bacteria leaks from your gut into the sterile environment, such as during leaky gut syndrome, this sets up an inflammatory response and increases your potential risk for a number of health conditions.

It All Starts in Your Mouth

Digestion begins in your mouth. As soon as you take a bite of food and begin chewing, saliva starts to mix with food. The enzymes in your saliva begin the process of breaking down the food particles to a smaller size. Your tongue works to form the food into a small ball in order to make it easier for swallowing.1

This is a complex process involving nearly 50 pairs of muscles and many nerves to prepare the food and move it from your mouth to your stomach.2 After chewing, your tongue pushes the food into the back of your mouth to trigger the swallowing response.

At this point, your voice box will close tightly so breathing stops in order to prevent the food or liquid from entering your lungs. After swallowing, the food enters your esophagus, which is the tube carrying food from your mouth to your stomach.3

Your stomach is like a sack with strong muscular walls. As the food enters, your stomach can actually expand. In addition to holding the food, it also mixes it up and secretes a powerful acid and enzymes to help continue the process of breaking it down.4

The time food stays in your stomach will vary between individuals and from men to women. After you eat, it can take between six to eight hours to pass through your stomach and into your small intestines.5

The Work of Peristalsis Moves It All Along

After leaving the mouth and before reaching the stomach, the food passes through the esophagus. This strong muscular tube uses a series of contractions, call peristalsis, to move the food to the stomach. At the bottom of the esophagus and just before the stomach is the lower esophageal sphincter (LES).

This valve is meant to keep the food from moving backward up the esophagus. If you have experienced heartburn, also called acid indigestion, it may have been the result of stomach acid released from the LES, causing a burning sensation in the esophagus.

During normal digestion, the LES opens to allow food to pass into the stomach but reflux may occur when the sphincter is weak or relaxes inappropriately.6 Peristalsis continues from the esophagus all the way through the digestive process to move your food to the end of the process. The series of wave-like muscle contractions cannot usually be felt.

As the food reaches your stomach, the churning turns the mixture into liquid. At the bottom of the stomach is the pyloric sphincter, a band of smooth muscle controlling the movement of partially digested food and juices from the stomach into the duodenum.

The pyloric sphincter opens with the force of contractions in the lower part of the stomach to allow a little of the liquid to pass into the duodenum, or the upper part of the small intestine. Your small intestine is a narrow, winding tube measuring approximately 20 feet when stretched out.7

Peristalsis continues to do its work, pushing food from the small intestine into the large intestine. This area is wider than the small intestine and measures just 5 feet in length. The entire length of human intestine can range between 25 and 28 feet long, curled and wound strategically within your abdomen.8

Your Liver and Pancreas Get Involved

Once the liquid reaches your small intestine, your liver and pancreas get involved. These two organs reside in your abdominal cavity in a sterile environment. The pancreas produces enzymes to break food down and the liver makes a green fluid called bile.

The pancreas is found behind the stomach, surrounded by the small intestine, liver and spleen. Nearly 95 percent of the organ is tissue that produces pancreatic enzymes for digestion. The remainder produces hormones to regulate blood sugar and pancreatic secretions.9

Juices and enzymes from the pancreas are designed to break down carbohydrates, fats and proteins and are delivered to the small intestine through small tubes called ducts.10 The liver contributes bile, a complex fluid containing electrolytes, organic molecules and water.

Within bile are bile acids, critical for digestion and the absorption of fat in the small intestines. An adult can produce up to 800 milliliters (3.3 cups) of bile each day. The detergent action of bile acids causes fat to break down into minute droplets.11 This is not digestion but is important as it increases the surface area of the fat, making it available to other enzymes for digestion.

Peristalsis12 continues the movement of the liquid mixture through your small intestine and into your large intestine. No further digestion occurs in the large intestine, but the mass continues toward the bowel as water is absorbed from the indigestible matter.

Your large intestine is made up of the colon and the rectum and is responsible for the absorption of certain vitamins made by bacteria that reside in your colon, including thiamine, folate and biotin.13 The mucosa of the large intestine also produces bicarbonate to neutralize the increasingly acidic waste products as they move down toward the bowel.

How to Tell if Your Stool Is Healthy

Since stool, beginning as food in your mouth, traverses the entire length of the gastrointestinal tract, it can give you clues about the health of your gastrointestinal tract. Living in the digital age means you no longer have to guess about the type of changes you may need to make in order to improve the condition of your stool, and thereby your health.

An online tool called StoolAnalyzer14 will help make suggestions for you based on the appearance of your stool shape, color, size, frequency and behavior. You receive a score on a 100-point scale with dietary recommendations to improve your health. While this is not a substitute for an ongoing relationship with a holistic health care provider, it may give you an idea of where to begin.

The next time you have a bowel movement you may want to compare what you see in the toilet against the chart below to gauge whether or not your stool is healthy or unhealthy. Simple dietary changes and a consultation with a holistic health care professional may help you quickly figure out what's gone awry with your digestive tract.

Healthy Stool Unhealthy Stool

Medium to light brown

Stool is hard to pass, painful or requires straining

Smooth and soft, formed into one long shape and not small pieces

Hard lumps and pieces, pasty and difficult to clean yourself or mushy and watery

About 1 to 2 inches in diameter and up to 18 inches long

Diameter is narrow, indicating a possible obstruction; infrequently is not so concerning, but if it persists definitely call you physician

S-shaped resulting from the shape of the lower intestines

Color is black, tarry or bright red indicating bleeding in the GI tract; black stools may result from certain medications, supplements or black licorice. If you experience this it is best to be evaluated by your health care provider

Natural smell, not repulsive (but not saying it will smell good!)

Color is white, pale or gray potentially indicating a lack of bile suggesting a serious problem, warranting a call to your physician. Antacids may also produce white stool

Enters the water quietly, no wet cannonball splash leaving your toosh in need of a shower

Color is yellow potentially indicating a giardia infection, gallbladder problem or Gilbert's syndrome. If you see this call your physician

Uniform texture

Presence of undigested food, especially when accompanied by diarrhea, weight loss or other bowel habit changes

Sinks slowly

Stool that floats or splashes on entry

Increased mucus in the stool associated with inflammatory bowel conditions such as Crohn's Disease, ulcerative colitis or cancer, especially when accompanied by blood or abdominal pain

Terrible odor should not be ignored. This is an odor above and beyond the usual objectionable stool odor, which can be associated with malabsorptive disorders, Celiac disease, Crohn's disease and chronic pancreatitis

Steer Clear of Constipation

The health of your gastrointestinal tract is measured not only by how your stool looks but how often you empty your bowels. Of course, nearly everyone experiences alterations to their schedule from time to time, but generally speaking, there's a few telling criteria you will want to evaluate.

While what's normal and healthy for a 21-year-old student compared to a 57-year-old commercial fisherman or a 71-year-old knitting fanatic may be different, some factors impacting your stool habits and frequency include lifestyle, diet and exercise.

According to Perfect Origins,15 depending upon your height, age and diet, you could be carrying around from 5 to 20 pounds of stool in your intestines at any given time. Failure to get rid of waste at regular intervals can trigger or exacerbate:

Upset stomach

Heartburn

Excess gas

Constipation

Diarrhea

Irritable bowel syndrome

Insomnia

Mood swings

Skin problems

Allergies

Since your bowel movements begin with what you eat, it makes perfect sense what you eat or don't eat has an impact on how your digestive system works. Fiber-rich vegetables are an important way to help ensure regularity.

Grains and sticky proteins like gluten, can cause constipation. Worse still, they may contain lectins leading to leaky gut. Factors that may lead to elimination alterations include:

The amount of fiber you eat

Sticking to an elimination routine

Exercise, or lack thereof

Hydration

Medications

Frequent use of laxatives

Poor nutrition

Iron supplements

Hormones

Medical conditions, such as Crohn's disease, colitis and even the flu.

How easily you evacuate your bowels may also be related to the position you're in when you're on the toilet. You might not have thought about it, but before toilets came along people used a different set of muscles to have a bowel movement.

The most effective means of evacuating your bowels completely is to be in a squatting position so your knees are closer to your chest. This optimizes the natural alignment of your colon. Using a squatting position may help prevent hemorrhoids, bowel diseases and help to keep your leg muscles strong, improving your balance inability to walk without assistance.

If you have a toilet that sits higher, you may not be able to squat over it. In this case, consider using a short stool to raise our knees into position while sitting on the toilet. You may help optimize your bowel habits by:

  • Eating 25 to 50 grams of fiber for every 1,000 calories and reducing or eliminating grain and processed foods
  • Staying hydrated until your urine is a light straw color
  • Getting at least 30 to 45 minutes of exercise each day and refraining from sitting as much as possible
  • Paying attention to the digestive side effects of any medications and supplements
  • Squatting during elimination

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