The 5 Facets of Digestion

The 5 Facets of Digestion

It’s not what you eat, it’s what you absorb!

Your GI tract is a complex system that runs throughout your entire body. It processes everything that you ingest, breaks it down, creates nutrients, and then sends it out to your body to be used. That’s pretty impressive, if you ask me! The GI tract is also the epicenter of your immune system, and therefore your health, so you'd better treat it right! Understanding what your body needs and how it processes food is essential to fueling your body the right way.

Let's take some time to understand digestion. Generally, there are five main components to your GI tract responsible for digestion: mouth, esophagus, stomach, small intestines, and large intestines. These five digestive components work together to extract nutrients from the food you eat, creativing the digestive process.


  • Chewing is the process that starts breaking down foods into smaller pieces.
  • Saliva has enzymes (salivary amylase) that start to break down starches.


  • Once food is swallowed, it travels down the esophagus.
  • The lower esophageal sphincter keeps the contents of the stomach in place and allows new food to reach the stomach.


  • The stomach is about the size of a fist and can expand up to 10 times its size.
  • With a PH of 2-5 (very acidic), enzymes begin to further breakdown protein (pepsin) and starches (gastric amylase).

Small Intestines

  • The small intestines is where the majority of digestion and absorption occurs by way of villi, tiny finger-like projections that increase surface area and absorption capacity.
  • The pancreas and the gallbladder secrete bile acids into the first portion of the small intestines to finish food breakdown.
  • With a surface area the size of a tennis court, the small intestines absorb nutrients that will be sent to the liver to be processed.

Large Intestines

  • Bacteria work on digested food and create additional vitamins.
  • The majority of water is absorbed here and food is prepared for elimination.

Digestion is an involuntary process, but choosing what foods to put into your body is entirely up to you! The amount of nutrients that are absorbed by the body are more important than the total amount present in the food you eat. Changing the structure of your food and combining different foods all play a large role in absorption. Manipulating the structure of food by blending or Blasting changes its cellular matrix, enhancing the release and absorption of the food in the GI tract.

Combining certain foods affects absorption of nutrients. For example:


-Non-heme iron found in plants is not as readily absorbed when ingested on its own. Add some Vitamin C and you have a recipe for enhanced absorption!

-Try sauteed kale with a squeeze of lemon on top

-Malic Acid found in pumpkin seeds, plums, and apples aids in the absorption of iron.

-Make a veggie stir fry and throw in some chopped apples.


-Calcium decreases the absorption of iron.

-The American Journal of Clinical Nutrition revealed a dose of 165 mg of calcium (as milk) reduced iron absorption 50-60%

-Caffeine inhibits calcium absorption and can deplete the amount retained by the bones.

Vitamin D, E and A (fat soluble)

-These need to bind to a fat source in order to be absorbed.

-Fat-free salad dressings do not provide the adequate fat needed to absorb the nutrients in salads.

-Try olive oil and vinegar for enhanced absorption.

Catechins (antioxidant found in green tea)

-80% of these antioxidants are retained when a slice of lemon is added to the tea.

-Be mindful of how much tea you drink, since the caffeine in green tea can decrease calcium absorption

Digestion and absorption are fascinating and we continue to learn more about this complex process every day. The structure of your food and nutrient interaction both play a large role in absorption. Understanding this process highlights the importance of eating simpl, clean, balanced meals to fuel your body.

Registered Dietitian, Certified Specialist in Sports Dietetics

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