It’s Just One Bite of Food

There are so many things going on in these miracle bodies of ours even just to process one bite of food, that it amazes me how we are still alive at all! As well as so many processes going on in parallel, there are so many things that can and do go wrong in this digestion process, it’s no wonder the pharma companies are making a fortune from all our foodborne diseases. Taking a pill for every ill is far easier for most people than doing the hard yards of working out what it is that you are doing or eating that is not serving you well. Well, that’s where Nutritional Therapy comes in.

I find digestion a fascinating topic. For example, the process that sits behind digesting each of the macronutrients – carbs, fats, proteins – is so fine-tuned that even today’s AI would struggle to replicate it.

Let’s take fats for example. When you eat something with fat in it, let’s be good and say an avocado. Even before you put the avocado in your mouth, digestion is starting as you look at it, the salivary glands get fired up and start releasing an enzyme called lingual lipase. This enzyme will start to work on the avocado in the mouth, breaking down the triglycerides (the technical term for fats) in the avocado into smaller units called monoglycerides and the lovely named “fatty acids”. You chew it all up and move the food to the back of your mouth where the upper esophageal sphincter – the gate between your mouth and your esophagus – opens up and you swallow the food down heading for your stomach.

Boom you’re done! Not quite.

Once it reaches the stomach, gastric lipase is secreted to continue the breakdown. As it gets churned around in the stomach, into a substance called “chyme”, peristaltic waves of muscle pulse through the stomach every 15 to 20 seconds to help move the food along and break it up even further. There is not much absorption taking place in the stomach, it’s mostly deconstruction work done by the HCL (Hydrochloric acid or stomach acid). Aspirin and alcohol are the main substances that are absorbed from the stomach, hence why aspirin can get to work so quickly and why it’s never a good idea to drink on an empty stomach.

The food, in the form of chyme now, moves slowly from the stomach into the small intestine or more specifically into the first section of the small intestine called the duodenum. There is another gate standing guard between the stomach and the duodenum called the pyloric sphincter. Once through this gate, pancreatic lipase is secreted to break down the triglycerides into monoglycerides and (short, medium and long chain) fatty acids.

The short and medium chain fatty acids are small enough to be absorbed into the bloodstream now but the long chain and the monoglycerides are still too big. This is where the gallbladder kicks in and secretes bile into the duodenum to emulsify or break these down into smaller units called micelles. Micelles are like a ferry system, they carry the fatty acids and monoglycerides over to the microvilli, then break away themselves. The monoglycerides and fatty acids recombine into a triglyceride once inside the absorptive cell.

So all of this work just to get recombined into the same thing that we started with – mental!

The last hurdle for fats is how to get into the bloodstream from the cell – triglycerides are coated in a protein (now called a chylomicron) which gives it a water-soluble coat which means it can now travel outside the cell. Chylomicrons travel to the lymphatic system where they enter into the bloodstream. Once in the blood, the chylomicrons are broken apart again and the triglycerides are released and stored by the body for use during times of fasting or in between meals.

This is just fats. At the same time, we are processing carbs and proteins, hormones are being fired off to kick start secretions, nerves are being triggered to conduct the movement of the food, the bacteria that live in our gut are waking up and getting ready to feed and much much more. And all of this happens for each and every bite of food we take.

If this isn’t the stuff of miracles, I don’t know what is.

If you want to see, visually, what happens when you eat a bite of food, this video is amazing. Please note that if you are squeamish, you might not be into this, it’s quite detailed.