The Gut and Nutrient Absorption

The gut is where nutrients are absorbed.  This is yet another reason why if your gut isn’t healthy, you’re not healthy.  You could be absorbing anywhere between 10% and 90% of nutrients from your food or any supplements you take.  Where you fall in this range could be a reason you struggle to lose weight.

We will always come back to the fact the digestive tract is a tube that is actually outside your body.  Think of it like a really long hole running down the middle of your body.  When you see it this way it’s easier to realize everything you put in your mouth doesn’t necessarily end up where it needs to go.  This is especially true when it comes to nutrients.

Nutrient Absorption and Hydration

In a healthy gut, nutrients are absorbed through the blood vessels behind the walls of the intestines.  They are absorbed either by passing directly through the mucosal lining of the small intestine, or by attaching something else and transported through the circulatory or lymphatic system.  Going back to my first habit, one of the things that can throw off nutrient absorption is your body’s level of hydration.  I’m sure I lost a lot of people when I made my first habit too simple and ordinary, but I’m convinced the majority of people don’t realize just how important proper hydration is to the basic processes of the body.

The digestion process requires 9 liters of liquid.  Now, don’t think you can suck down a liter or two of water with your meal to make this happen.  This liquid mostly comes from saliva, bile, water, electrolytes, mucus and enzymes.  So it has to be there to begin with.  If you are not adequately hydrated, you will be lacking in these essential fluids when your body needs them.  The best way to stay hydrated is to drink water throughout the day.  Your kidneys can only filter, at most, a liter of water an hour, so the best way to hydrate is consistently throughout the day.

What does this have to do with Weight?

If you are not adequately hydrated, your body cannot send all that it needs to the intestines to break down food and absorb the nutrients and fluid back into your system.  If you do not properly absorb nutrients, you are starving your cells and your body keeps looking for the nutrients it needs to support all of its processes.  Where does it look to for nutrients?  More food of course.  So no matter how many veggies you’re eating, or anything else for that matter, if the nutrients can’t get through to your cells, they’re not doing you much good, other than the fiber that’s moving things along or feeding your gut biome.

Another reason nutrients don’t get fully absorbed is when there is inflammation present in the layers of the intestinal wall.  Your digestive tract is lined with a mucosal lining that has four layers.  The outer most layer regenerates every 3-4 days.  The second layer contains blood and lymphatic vessels which absorb nutrients.  Between these layers and the two behind that, is fluid.  When inflammation is present, there’s a buildup of excess fluid (from inflammation, not proper hydration) between the outer mucosal wall and the capillaries that take in the nutrients.  This excess liquid makes it harder for nutrients to get through to the capillaries.

What about Hormones

The gut has more endocrine cells than anywhere else in your body.  The job of the endocrine system is to secrete hormones.  The gut is the largest endocrine organ in the body.  I talk a lot about endocrine disruptors (you can read about how toxins affect our bodies here), but I haven’t yet discussed their impact on the gut.  If the gut is our largest endocrine organ, and endocrine disruptors, well, disrupt the endocrine system; what impact are they having on digestion and nutrient absorption?  Well, we already know that endocrine disruptors, like the BPA in plastic water bottles and other plastics have been linked to obesity; other endocrine disruptors include phthalates, heavy metals and flame-retardants.1  More research needs to be done to get to the full impact of endocrine disruptors, but based on the attention around leaky gut I will not be surprised to see this information coming out soon.  Although not soon enough.

The gut relies on five different hormones for digestion and two hormones for signaling the brain that the stomach either does or doesn’t need food.  The first hormone in the digestive process is called gastrin.  Gastrin is secreted as a messenger to tell the stomach to release hydrochloric acid and pepsin – a digestive enzyme that breaks down proteins.  It also stimulates the growth of the stomach lining and motility.  Although some may not consider caffeine and alcohol as endocrine disruptors, their presence in the stomach lowers the pH of the stomach which inhibits production of gastrin because when pH is already low, gastrin is not called upon to do its job.  Do you see where I’m going with this?  Alcohol and caffeine can interfere with the digestion process when consumed at a time when gastrin is needed.  If stomach acid is already being lowered by an outside agent, gastrin thinks its job is done and we miss out on all of the work gastrin does in the stomach.  We upset the balance.

The other hormones have key roles as well. Gastric inhibitory peptide slows down the churning of the stomach and inhibits acid as the stomach releases partially digested food into the small intestine – which needs a higher pH.  It also induces insulin.  Secretin regulates water and pH in the small intestine to protect the next batch of enzymes that come in to work.  Cholecystokinin stimulates the gallbladder to release bile into the small intestine and releases digestive enzymes in the pancreas to assist in the break down of fats.

Back to insulin.  Insulin is a hormone made in the pancreas and is released to help with the absorption of sugar.  We’ll talk more about insulin down the road, just keep in mind that digestive hormones, and digestive health, play a role in the release of insulin.

The other two hormones are ghrelin and leptin.  Ghrelin tells our brain the stomach is empty and we’re hungry.  Leptin decreases hunger.  We’ll cover those later as well.

We’ve only scratched the surface, but already you can see how delicate the balance and complex the functions of the digestive system.  It’s called the second brain for many reasons.  Physiologically it can operate even without the brain in our skull.  The gut has it’s own nervous system with a network of neurons that keep digestion going even when we have no idea what’s going on down there.

If you take nothing else away from this post, I hope it at least gets you to start thinking about what you eat and drink, as well as how environmental factors can impact the health of your gut.  And if at any point you feel like you want to dive in and start implementing a strategy for increasing your gut health, well, you know where to find me.  My services are available to you no matter where you are in this world.

Click to learn more about me and health coaching.

Until next time…

Yours in Wellness,


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