How Does the Digestive System Work?
Everything you ever wanted to know about your stomach, explained.
What is the digestive system?
The digestive system courses through the body and lets people take in nutrients and release waste, according to David Kahana, MD, a Board-Certified gastroenterologist with 1MD. The system essentially consists of all the organs that help the body digest food. According to Carolyn Newberry, MD, a gastroenterologist at NewYork-Presbyterian and Weill Cornell Medicine, these organs include the esophagus, stomach, small bowel, colon, pancreas, liver, and gallbladder. “These different organs work in concert to break down food, mix it with digestive enzymes, and extract nutrients that can be used by the body,” says Dr. Newberry.
Why do we need to digest food?
Digestion allows us to take the food we eat and break it down into simple parts to the bloodstream absorbs and uses it for energy, says Dr. Newberry. Without digesting and breaking down food, the body can’t absorb the necessary nutrients, explains Dr. Kahana. That’s just one of the many things your stomach wants you to know.
So what happens to your food after you eat?
Here’s the order of events: The food enters the mouth and travels into the esophagus. Then, it moves to the stomach and small bowel or small intestine where it mixes with digestive fluids from the pancreas, liver, and gallbladder. The small bowel absorbs important nutrients and water. The circulatory system sends some of these nutrients to parts of the body to store or use them, per the NIH. Any waste, or undigested food material, moves to the colon or large intestine where it takes another one to two days to leave your body, says Dr. Newberry.
How long does it take to digest food?
The time it takes to digest food varies from person to person and food type to food type. But Dr. Newberry says people digest a meal and eliminate it within one to three days. Dr. Kahana notes that the stomach specifically empties halfway in about 90 minutes post-meal—meaning it’s empty after six hours into the small intestine before going to the colon or large intestine and finishing up the digestion process. A Mayo Clinic study found that food hangs out in the large intestine 33 hours for men and 47 hours for women. That’s not the only obscure body fact you never knew about your own body.
Digestion doesn’t only take place in the stomach
One myth Dr. Newberry wants to dispel is that digestion takes place completely in the stomach. Although the stomach is key and is the main site of the “mechanical break down” of food, Dr. Newberry says nutrient absorption occurs further down in the small intestine and colon. And according to Dr. Kahana, a big misconception is that the body absorbs nutrients passively when it actually takes energy to do so. “Each individual nutrient has to be recognized as a food and not a foreign invader,” says Dr. Kahana. “It’s then actively absorbed into the body via specific nutrient transporters.”
No, food doesn’t “go right through” you
Having a bowel movement right after eating a meal doesn’t mean the food is going right through you, according to Dr. Newberry. “The body has a mechanism to make more room for food after eating called the gastrocolic reflex,” she says. “This reflex stimulates the colon to contract after eating, which may result in a bowel movement.” These movements include waste from meals you eat one to three days beforehand.
Your digestive system does a good job
Another rumor is that people need periodic bowel cleanses to “remove toxins” from the body. It’s one of the 59 rampant health myths that need to die. In fact, the digestive tract is an expert in removing waste from the body—it doesn’t need extra help from commercial bowel cleanses. “These cleanses can also lead to dehydration and loss of electrolytes which can lead to big problems, especially in people with heart or kidney disease,” says Dr. Newberry.
How can you keep your digestion healthy and normal?
The best way to keep things regular in your digestion is to follow a balanced diet full of fruits, vegetables, whole grains, and lean proteins, Dr. Newberry says. Stay clear of these foods that are bad for digestive health. Drink plenty of water, and stay active.