I started writing a bit about digestive issues and then I realized that I should probably start at the beginning and describe how digestion works when it’s functioning optimally. Digestion is a north to south process, but until I was studying it I didn’t really have a good grasp on how the organs interact with each other.
Digestion is defined as the mechanical and chemical breakdown of food. Proper digestion breaks food down into molecules that are small enough to be absorbed by the body’s cells. This is how we get the nutrients that are reassembled and used to make our entire body!
When training to become a Nutritional Therapist we learn that digestion is the foundation that all the body’s processes rest on. If you have a problem anywhere in your digestion it will eventually lead to other health problems. If your fats, proteins and carbohydrates aren’t properly broken down in to their individual parts, how will you successfully build new cell membranes, muscles, or neurotransmitters?
Digestion begins in your northernmost organ – your brain. The thought of food or the site & smell of food are what triggers your salivary glands to kick up production of saliva. When you put a bite of food in your mouth your teeth grind it smaller and your saliva mixes with it to lubricate things and start breaking down the carbohydrates. Chewing begins the mechanical breakdown of the food, sparing your stomach from having to do so much work. Notice the difference in how your stomach feels after a rushed meal where you’ve “inhaled” your food compared to a relaxed meal where you have taken the time to chew things a few extra moments. That bloated or achy feeling may be your stomach complaining that it’s overworked.
When you swallow, the mix of food goes down your esophagus and through the Lower Esophageal Sphincter (LES) into your stomach. This is the valve that typically works one-way to keep your stomach acid contained (when it works inappropriately you get heartburn – more on this in a future post). The stomach is muscular and it moves and contracts to continue to mechanically break down the food, while gastric juice is secreted and these chemicals starts to work on it at the same time.
It’s important that the stomach maintain a very acidic pH of between 1.5 – 3.0 in order to work optimally. This turns the food into a paste-like consistency that is then ready to be released into the first part of the small intestine, called the duodenum. Since the pH is still so acidic, the pancreas is triggered to release some bicarbonate (yep, like baking soda) to return it to a neutral pH of 7 so the rest of the intestine doesn’t get burned. Then the pancreas secretes enzymes to further break things down, and the gall bladder secretes bile to emulsify the fats so they will be the proper size to be absorbed. At this point the food is almost totally digested and is ready to be absorbed.
Muscular action of the small intestine moves the components through and millions of tiny, finger-like, villi grab a hold of the nutrients so they can be carried into the body through the blood and lymph system. 90% of what nourishes you is absorbed in the small intestine!
The leftovers, which consists of undigestable fiber, water, bile, and old cells, gets pushed through to the large intestine, aka colon. Here the water gets recycled and missed nutrients get captured and turned in to vitamins K, B1 & B12. What’s left after that becomes the feces and exits to the south.