I see a lot of patients who are interested in finding the perfect diet, and I always get asked questions about the latest trends in nutrition. Inevitably, I steer the conversation towards the topic of digestion. Digestion is the process of breaking down the food we eat into base nutrients. This is done so the nutrients can be absorbed and used by our body. Nutrition, on the other hand, refers to nutrients required for metabolic needs. Our state of health is just as dependent on how we digest and absorb food, as it is on what food we eat.
“You are what you eat … and absorb!”
The digestive system has several functions:
- to break down and absorb nutrients
- to create a barrier between your body and the external environment
- to excrete waste and is a part of our immune systems.
It is made up of our Gastrointestinal Tract (GI Tract) and the accessory organs that support it. The GI Tract starts at the mouth and ends at the anus, while the accessory organs include the nervous system, the tongue, teeth, salivary glands, the liver and gallbladder, pancreas and the microbiome. These must all work together to complete the digestive process.
Journey of an Apple with Nut Butter Through the Digestive System
To illustrate the digestive process, we can follow an apple with nut butter as it is eaten, digested and then excreted.
Step 1: The Cephalic (Head) Phase
Digestion doesn’t start with the first bite. It starts with thinking about the first bite! When one starts to think about eating, or smell something in the oven, it sets off a series of signals to the body to prepare itself for a meal. First, our body starts to secrete saliva in the mouth and stomach acid (HCl) in the stomach. This process also alerts the small and large intestines to prepare to propel food through our body as we eat.
Step 2: The Oro-Esophageal Phase
This is where we first bite into the apple and nut butter. As we chew the food, we are mechanically digesting it; breaking it down into smaller pieces for further digestion. The taste and scent of the apple with nut butter help to reinforce the cephalic phase. Saliva begins to chemically digest the food, as well as to lubricate it so that the tongue can push the mashed up apple and nut butter towards the esophagus, where it is then swallowed and propelled towards the stomach.
Step 3: The Stomach Phase
The Stomach secretes stomach acid (HCl), mucous and enzymes. Once the apple and nut butter mush enters the stomach, it mixes with the HCl. The HCl activates enzymes to help chemically digest the mush. All the while, the stomach churns to create a mixture of mush. This mixture of HCl and enzymes is now called chyme. The esophageal sphincter stops it from travelling backwards, while the pyloric sphincter opens to allow the chyme to move along the digestive tract. The role of the mucous is to create a protective coat to prevent the HCl from burning the stomach wall.
Step 4: The Small Intestine Phase
Once chyme enters into the small intestine, the liver and gallbladder release a fluid called bile. Bile has two functions. It is a detergent that dissolves fat into smaller particles so they may be further digested, and it serves as a way for the liver to release metabolic waste for excretion. Meanwhile, the pancreas releases enzymes to help break down fats, proteins and carbohydrates. 90% of the vitamins, minerals, fats, proteins, carbohydrates and water in our diet are absorbed in the small intestine.
The microbiome is comprised of trillions(!) of bacteria living in the GI tract. While most of them exist in the large intestine, some live in the small intestine. There are over 100 different species and together make up 3-4lbs of your total body weight. They are beneficial to us because they help in the development of the intestinal tract, they provide a barrier from unhealthy bacteria, as well as interacting with the immune system throughout the GI tract. They also produce vitamins for us, such as Vitamin K and biotin (Vitamin B7).
Step 5: The Large Intestine Phase
Once the chyme has reached the end of the small intestine, most of the nutrients have been absorbed and what’s left is now known as feces. As it is propelled through the large intestine, through a process known as peristalsis, water and electrolytes such as sodium are pulled back into the body. By the time it reaches the terminal end, the feces is much more solid and we are ready to have a bowel movement. The entire process takes 6-8 hours.
How’s your poop?
The quality of your stool can provide a lot of information about how your digestive system is doing. My definition of a “Rock Star poop” is one that is well formed, light to medium brown in colour and easy to pass. There should be no undigested food, blood or mucous in it and you should feel completely voided after the fact. I often use the Bristol Stool Chart to help my patients classify their stools. Ideally, stool should be a type 3-4.
Importance of Digestion and Absorption
The old saying “You are what you eat” is only part of the picture. It is more accurate to say “You are what you eat, and then absorb.” Symptoms such as gas, bloating, nausea, indigestion and abnormal bowel movements all serve as signs of a digestive system in need of support. This is important both from a comfort perspective, but also because the nutrients from food are needed to maintain our health. In the long term, poor digestive health can lead to nutrient deficiencies, fatigue, fractures and increased infections. If you have frequent digestive problems, naturopathic medicine can help identify the cause and repair the digestive system to help improve your health. Take action to regain your health.