Digestive system: Full circle from mouth to body cells
In order to really develop a relationship with food and how it effects us and our body, I believe it’s important to understand how our body works and what actually happens with the food we eat.
As mentioned in my previous posts, I wanted to start with cells, as they are the building blocks of everything in our body (from skin, bones, muscle, organs, to blood etc.) and it’s ultimately the cells and their function that we provide with nutrients from our food.
I wrote various drafts for this post, where I described an individual cell with the analogy of an autonomous city, which has a border wall (= Cell membrane), a central government (= Nucleus), various power plants (= Mitochondria), factories (= Ribosomes) and more. I went to great length, to describe different kind of cells, like red blood cells which are special as they don’t have a Nucleus in order to create more surface to carry as many oxygen molecules as possible, etc.
While all that is super fascinating, I started to question how practically helpful that would be to you, and ended up scraping all of these drafts with the intention to focus on digestion instead. This is not just more practical but also more directly related to food, and that’s ultimately what this newsletter is going to be all about. There will be lots of cooking, and while deliciousnes is high up on my priorities, the focus will always be how the food benefits our health.
You have probably heard the phrase “You are what you eat“, right?
While it’s of course essential what you eat, we need to think about how that food ends up with your cells, and for that it’s essential that you digest, absorb and don’t excrete required substances that you ingest.
Therefore it’s more accurate to say:
You are what you digest
You are what you absorb
You are what you don’t excrete
Your digestive system
Your digestive system begins at the mouth and terminates at the rectum, and while the length obviously varies among individuals, it's around 9 meters long. While food passes through the digestive system, it is broken down mechanically and chemically so it can be absorbed and distributed to be utilised by your cells.
Let's have a look at the full journey your food takes…
Mouth: This is where it all starts. As soon as you take a bite of food, your teeth break it down into smaller pieces. Your saliva (spit) mixes with the food, helping to make it soft and slippery. Saliva also contains enzymes that start to break down some carbohydrates (like bread and pasta) right in your mouth.
You can actually test that yourself - keep a potato in your mouth chewing for more than a minute and you will start to taste sweetness.
Throat and Oesophagus: Once you're ready to swallow, the chewed food moves from your mouth through a short tube called the throat (or pharynx). From there, it enters a longer tube called the oesophagus. Little rhythmic waves, almost like a gentle squeeze-and-push dance, help move the food to the stomach. This dance is called "peristalsis."
Stomach: Welcome to the food mixer! The stomach muscles churn and mix the food with acid and enzymes. These acids and enzymes help break down the food further. Think of the stomach like a blender, turning your chewed food into a mushy liquid.
Don't drink while you're eating. Instead, have a drink at least half an hour before you eat. Imagine your food as a sponge; you want it to soak up the stomach acid, and it can do that better if it's not already drenched in water.
Small Intestine: After the stomach, the food enters the small intestine. This is a super long, coiled tube (about 20 feet long!). Here, the real magic happens. Nutrients (like proteins, fats, and sugars) from the food are absorbed into your bloodstream. This gives your body energy and materials to grow and repair itself.
Liver, Gall Bladder and Pancreas: The liver and pancreas send special juices to the small intestine. The liver makes bile, which is stored in the gall bladder. When you eat something fatty, the gall bladder squeezes out stored bile into the small intestine to help digest that fat. It's like having a squirt bottle of dish soap ready to tackle a particularly greasy pan. The pancreas makes enzymes that help digest all types of food. They're like the special sauce that helps with digestion.
Large Intestine: Anything that's left – the stuff your body doesn't need – goes into the large intestine. This is a shorter but wider tube (about 5 feet long). Here, water is absorbed back into your body, and the leftover waste becomes more solid, turning into poop.
Rectum and Anus: The final stretch! The waste (now in the form of poop) gets stored in the rectum, the last part of the large intestine. When it's time for a bathroom break, the waste exits the body through an opening called the anus. And there you have it, the end of the journey!
So your digestive system breaks down the food, absorbs all the good stuff, and gets rid of the rest!
Your gut & immune system
Along the digestive system, not only is food processed, but there's also a ton of interaction with various tiny creatures, mostly bacteria, called "gut microbiota." Imagine them as millions of tiny little tenants living in a big apartment complex (your gut).
Now, your immune system is like the body's security team. Its main job is to protect you from harmful invaders, like bad bacteria or viruses.
Guarding the Gates: A large part of your immune system is stationed in and around your digestive tract. Think of them as security guards patrolling the hallways of the apartment complex. They're always on the lookout for troublemakers or harmful invaders.
The Good Tenants: Many of the bacteria living in your gut are friendly and beneficial. They help with digesting food and even produce some vitamins. Your immune system recognises these friendly bacteria and lets them go about their business.
Dealing with Trouble: If harmful bacteria or viruses try to settle in, the immune system springs into action, getting rid of the invaders to keep you healthy.
Communication is Key: The bacteria in your gut also help "train" your immune system. They teach it to tell the difference between friends (good bacteria and food) and foes (harmful bacteria and viruses). This training helps the immune system react correctly and not overreact, which can lead to issues like allergies or autoimmune diseases.
Support Crew: The gut and its bacteria also produce certain substances that help regulate and support the immune system, ensuring it works efficiently.
Brain of your gut
So, you know how your brain in your head is like the big boss controlling many things in your body, right? Well, your gut, the long tube that digests your food, has its own mini-brain! It doesn't think thoughts or dream, but it does a lot of work on its own without needing instructions from the big brain upstairs.
Your gut brain manages a lot of the digestion dance on its own. Like mixing food in the stomach, absorbing nutrients in the intestines, and moving things along. All this happens without you or your big brain having to think about it.
Have you ever felt "butterflies in your stomach" when you're nervous? Or maybe your stomach gets upset when you're stressed? That's because the gut and brain talk to each other. Emotions and feelings can influence how your gut works, and vice versa. We’ll get back to how stress can negatively impact your digestion in just a moment.
Your nervous system has two main parts that help decide how your body should act, especially in times of peace or stress: the parasympathetic and sympathetic systems.
Parasympathetic Nervous System (‘rest and digest’)
This is like the "chill out" or "relax" mode for your body. When it's active, it tells your body it's a good time to focus on things like digesting food or healing. Think of it like a green light saying, "All good, let's digest that yummy food!" It helps increase things like saliva production in your mouth and the churning and absorbing actions in your stomach and intestines.
Sympathetic Nervous System (‘fight or flight’)
This system preps your body for action, like if you're in danger or super stressed. It's like an alarm bell saying, "Be ready to run or fight!"
It puts digestion on the back burner. Your body decides there are more pressing issues than processing food. So, it might slow down or temporarily halt things like stomach churning. This is why if you're super nervous or scared, you might feel like you have a rock in your stomach or lose your appetite.
In many ways, stress has become a significant concern in modern society, and many experts and researchers refer to it as an "epidemic." The fast-paced nature of contemporary life, combined with technology, work pressures, societal expectations, and global uncertainties, contribute to elevated stress levels for many individuals.
I don’t know about you, but I can’t wait to get to actual food and healthy cooking very soon, but before then, we must have a look at proteins, carbohydrates and fats, as there is lots of confusing information out there, and it really helps to understand how those so called “macronutrients” actually work with your body, what’s needed and what’s too much.
Thank you for reading and see you next week!
Enjoy your food!
Michael