The ability to fully digest and absorb protein means the difference between killing or maximizing muscle gains and fat loss, as well as your overall hormonal balances, energy levels, inflammation, and health.
So, understanding exactly how it works and how to keep it, or get it, working properly is very important.
Let’s look at this.
When you consume food, you chew it and it goes into your stomach.
Here we see mostly protein digestion, with fats and carbs mainly digested in the small intestine.
When protein comes into your stomach, it releases two main things: hydrochloric acid, or stomach acid, and an enzyme called pepsin.
This stomach acid does a few things: it helps break down proteins, breaks down minerals necessary for later protein synthesis in the body; and it kills bacteria, fungi, parasites, and viruses coming in with your food and water.
Now, these proteins you ate are each made of hundreds or thousands of individual amino acids, all bonded together in long chains like a beaded thread and then coiled up, with the coils also bonded together to hold it all together as a "protein".
So first, the stomach acid breaks the bonds holding the coils together, so it’s just one long chain. Then the pepsin starts breaking the bonds that hold the overall chain together. It doesn’t break all of them, but it breaks a lot. So by the end of this, instead of each protein molecule being a long chain of hundreds or thousands of amino acids, it’s now broken up into many much smaller chains of maybe 20 to 40 amino acids each.
Now, this whole time, the level of stomach acid has been rising. And, by the time these amino acid chains are broken up, the stomach acid should have reached a pH of about 1 or 2 (pH is just a measurement of how acidic something is or isn’t, with 1 being the most acidic). The stomach can handle this level of acid because of a mucous lining it has along its walls.
But it needs to get to a pH of 1 or 2 because this is the trigger that signals the valve between the stomach and small intestine to open and let the food through. If the stomach acid didn’t get this acidic, then the food would stay in the stomach much longer and go rancid. Then it would start bubbling up and burn the esophagus, which isn’t made to handle this acid. This is heartburn and acid reflux when there’s not enough stomach acid — not when there’s too much.
So we want it very acidic. If it’s not, then you get heartburn, but also, you get proteins that aren’t broken down enough. And they need to be, as you’ll see.
From here, the food moves into the small intestine where more enzymes come in, further breaking these short amino acid chains up until they’re just free-floating individual amino acids — no more beaded threads, just beads.
Other enzymes also start breaking down the fats and carbohydrates, and all of these broken down pieces start moving through the intestinal wall into blood vessels that take them to the liver. The liver then filters all of this, looking for any toxins which it tags so the kidneys know to get rid of them, and then lets it all out into the bloodstream.
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But this protein breakdown is important here. The amino acid chains must be fully broken down into individual amino acids for a few reasons.
First, if they are fully broken down, then the body can use them to build new proteins and collagen in the forms it needs for muscle, bone, hormones, enzymes, etc.
But if they’re not fully broken down, the body can’t use them. At all.
In this case, they continue down and leave as waste, or... they’re absorbed into the bloodstream and cause inflammation in the body.
This is because of those bacteria, fungi, parasites, and viruses I mentioned coming in with your food, henceforth to be known as foreign invaders—because they are your enemy.
These come into the stomach through food and water, and this is fine because if your stomach acid gets acidic enough, it kills them off before they get to the small intestine.
But if it doesn’t, or if some of them do get through, which happens, your body has a solution.
Your small intestine is surrounded by three walls. The first is an inner lining about one cell in thickness which sees the broken down nutrients and lets them through. The third wall is all the blood vessels surrounding the intestine which take these nutrients to the liver. But the second wall, between these two, is made of immune tissue. Lymph tissue, to be exact.
This is why you’ve heard that about 80% of your immune system is in your gut. This is it.
When food comes into the small intestine, this lymph tissue sends out immune cells to check for any foreign invaders. And when the immune cells find some, they send antibodies to surround and destroy them.
This is an immune response. And there’s always some inflammation during an immune response. So if there were a lot of bacteria, like salmonella poisoning, you might get a belly ache. This is from the immune response, not from the salmonella.
But the way they recognize these bacteria, parasites, and fungi is by their shell, or outside coating, which is made out of protein.
Remember, any protein the body needs is already broken down into individual amino acids at this point. They know this. So these whole protein structures (bacteria, parasites, etc.) must be foreign invaders.
So they either kill them then and there or maybe some make it through and into the bloodstream and land somewhere in the body, in which case the immune cells go there to kill them. And in this case, we feel inflammation at the spot where they landed due to the immune response.
But the immune cells also remember the exact protein structure of these invaders so they know them in the future. They have to so they don’t mistake the body’s own protein structures for harmful bacteria and attack them (that’s what an auto-immune disease is, the body mistaking itself for harmful invaders and attacking itself).
But now look at this... if your digestive system didn’t fully break down all your protein into individual amino acids and then some of the partial amino acid chains got out into the bloodstream, then when the immune system sees these, it knows they aren’t individual aminos, and it knows they aren’t bodily protein structures. So it assumes... they must be harmful bacteria.
So it launches an immune response against these partially broken down proteins. And immune responses create inflammation.
Now, if this happens on a daily basis because you have low stomach acid, it causes a continually created inflammation in the body wherever these partial proteins landed.
This means a continual extra load on your immune system, which is needed for muscle building and overall health, and it also means a continual source of stress for the body, which means a continual releasing of cortisol, the stress hormone, that both breaks down muscle, instructs the body to store fat, and throws off other hormones like testosterone, growth hormone, estrogen, progesterone, and thyroid.
This might be so little that you don’t notice, or it may show up as fibromyalgia or lethargy, or rheumatoid arthritis when these land at the joints, or just, "my body hurts."
Either way, this doesn’t work for building muscle or losing fat.
Also, if we have low stomach acid levels here, and more harmful bacteria make their way into the small intestine without being killed in the stomach, they can take root in the intestine and grow. It’s not acidic there. It’s dark and it’s warm. They love it!
And they start to consume some of the food you ate.
What do they give you in return? Gas and bloating.
They’re not good tenants.
But now, not only are you losing some of the protein you ate from it not being fully broken down, you’re also losing it to these bacteria who eat some of it, and to cortisol released due to inflammation, which breaks down muscle and increases fat storage.
This may seem small. It's not.
It affects our hormones, energy levels, hunger cravings, and our ability to gain and lose muscle and fat.
If we don’t get all the food that we’re consuming because it’s not broken down enough, or it’s being consumed by bacteria and parasites, then we’ll still be hungry even if we eat a lot.
We’ll have cravings created by these bad bacteria, especially for fast-acting sugar, which can raise fat storage, and we’ll have less amino acids for building muscle, making hormones that direct our body to build muscle, and for enzymes that break down our fat.
These chemicals are made, perform their function, and are then gone. They need to be constantly replaced inside the body.
So we need these proteins fully broken down and we need these bacteria killed off.
And most people have some degree of lowered digestive acid these days, causing plenty of trouble in their bodies. In fact, this is one of the biggest causes of muscle loss as we get older—lowered digestive ability.
I know that was long, and we touched on several points. Over the next several articles, we’ll dive deeper into acid reflux, bacterial infections, prevention of muscle loss, auto-immune conditions, how digestion affects our mood, as well as cravings.
Bacteria in your body, whether harmful SIBO, or helpful bacteria in your colon (your microbiome), are able to communicate with your brain via the same channels the cells in your body use — as if they were actual cells in your body.
If you haven’t had sugar in a while they get hungry. And they’ll communicate that hunger, just as your cells will, giving you an exact craving for the type of food they like.
If you try to come off sugary foods, starving them, they’ll get back at you and make you feel their pain until you go buy that donut.
That’s where those cravings are coming from.
