Understand the structure of the intestine and promote lasting gut health

Your gut feeling rarely lies—and there is a good reason for that. The structure of the intestine is far more than just a simple digestive tube. Instead, think of it as the central control center for your overall health, from supplying your body with energy to defending against disease. This fascinating organ plays a major role in determining how you feel every day.

Why your gut is the foundation of your well-being

Of course, when you think of the gut, digestion is probably the first thing that comes to mind. While that is one of its main functions, its true significance extends much, much further. Your gut is more like a vast, intelligent ecosystem that forms the crucial interface between the outside world and your body’s interior.

Everything you eat and drink has to pass through this one critical barrier. And this barrier is immense: If the entire surface area of the intestine were spread out, it would cover the size of a tennis court. This makes it the largest point of contact between your body and the outside world.

The command center of your immune system

What many people do not know: About 80 percent of your immune cells are located in the gut. There, they form a powerful army that constantly distinguishes between friend (nutrients) and foe (pathogens). This is an impressive figure that immediately makes it clear why a healthy gut is so crucial for your immune defenses.

When the intestinal barrier is intact, only beneficial, fully digested nutrients can pass through, while intruders and undigested particles are blocked. If you are interested, you can learn more here about how the intestine functions as a protective shield for the body.

Your intestine is not only responsible for digestion but is also the headquarters of your immune system. A healthy gut is therefore the foundation for strong defenses, more energy, and your overall well-being.

A perfect team: the small intestine and large intestine

The intestine itself mainly consists of two major sections that work together as a perfectly coordinated team to provide your body with everything it needs. Each has its own specific tasks:

• The small intestine: It is the main player when it comes to breaking down your food into its smallest components. This is where vitamins, minerals, fats, proteins, and carbohydrates are absorbed and made available to your body.
• The large intestine: Its task is to remove water and important electrolytes from the remaining food pulp. It forms the stool and is also home to most of your beneficial gut bacteria—the microbiome.

This interplay not only ensures your nutrient supply but also directly affects your energy, mood, and overall vitality. Once you understand the structure of the intestines, you quickly realize how important it is to support this organ deliberately.

Instead of feeling your way in the dark, a personalized test such as the mybody®x gut health test can give you concrete insights into the state of your microbiome or possible inflammatory markers. This finally enables you to take targeted measures for your health.

A journey through the small and large intestines

Imagine your food embarking on an exciting journey. The first and longest stop after the stomach is the small intestine—a true marvel of nature and your body's central sorting and loading station. At an impressive length of three to six meters, it is where the real magic of nutrient absorption happens.

But the small intestine is not a simple tube; it is a highly specialized organ divided into three sections. Each has its own essential role in the bigger picture.

The small intestine: Where your body refuels

The journey begins in the duodenum. This is exactly where digestive juices from the pancreas and gallbladder arrive. Their task is to neutralize the aggressive stomach acid and begin breaking down fats, carbohydrates, and proteins into their smallest usable building blocks. In a sense, it is the preparation for actual nutrient absorption.

Next, the process continues into the jejunum (empty intestine) and the ileum (curved intestine). This is where most absorption takes place. Imagine a huge internal surface folded into countless villi and microvilli. This ingenious structure ensures that vitamins, minerals, amino acids, fatty acids, and sugar molecules can pass efficiently into the bloodstream.

• Jejunum (empty intestine): It specializes in absorbing sugars, amino acids, and fatty acids. It also takes up most vitamins and important minerals such as iron here.
• Ileum (ileum): This final section focuses on the absorption of vitamin B12 and bile acids, which are later recycled. It also plays a very important role in your immune defense.

When this process works smoothly, your body is optimally supplied with energy and all the vital building blocks it needs. Problems in the small intestine therefore often become apparent directly through fatigue, nutrient deficiencies, or digestive issues. You can read more about how the intestine works in detail and what other tasks it performs in our article about the functions of the intestine.

The large intestine: Master of recycling and home of your microbiome

After the small intestine has extracted all the valuable nutrients, the remaining chyme enters the large intestine (colon). This approximately 1.5 meters long section has a completely different, but no less important, task. You could describe it as your body’s recycling and final processing station.

Its main function is to remove water and essential electrolytes (salts) from the remaining chyme. This process is crucial for your fluid balance and the formation of stool. Without the large intestine, your body would lose enormous amounts of water.

The large intestine is responsible not only for forming stool but also serves as the home of trillions of beneficial bacteria—your microbiome. These little helpers produce important vitamins (such as vitamin K) and short-chain fatty acids, which serve as an energy source for intestinal cells and have anti-inflammatory effects.

This final section of the digestive tract takes care of the finishing touches. A healthy large intestine and a balanced microbiome are essential for regular bowel movements, a strong immune system, and protection against pathogens. An imbalance here can lead to symptoms such as bloating, constipation, diarrhea, or irritable bowel syndrome.

The interplay between the small and large intestines is a perfect example of your body’s efficiency. Only when both organs perform their tasks optimally in the structure of the intestine do you feel energized, healthy, and completely well.

The intestinal wall: More than just a shell

After looking at the small and large intestines in their full length, let’s now zoom in really closely. Don’t think of your intestinal wall as just a passive shell. It is a highly intelligent, multilayered barrier—your personal bodyguard, deciding what from your food is allowed into your body and what must stay out.

This diagram gives you an initial overview of the broad division into the two main areas: the small intestine and the large intestine.

Each of these areas has a specialized wall structure perfectly tailored to its functions. The intestinal wall consists of several layers arranged like the layers of an onion: the mucosa on the inside, followed by a connective tissue layer (submucosa), then muscle layers (muscularis), and an outer covering (serosa).

But when it comes to your well-being and health, one layer in particular is the absolute superstar: the innermost layer, the intestinal lining.

The intestinal lining: Your inner shield

The intestinal lining is your body's frontline. It is remarkable: it is only a single layer of cells thick, yet it carries enormous responsibility. This wafer-thin layer decides with every bite you eat and every sip you drink: What is friend, and what is foe?

Nutrients are allowed to pass through, but pathogens, toxins, and undigested particles must stay out. To ensure that this important boundary remains truly sealed, the individual intestinal cells are connected by so-called tight junctions. The best way to picture them is as extremely tight, seamless zippers that ensure nothing unwanted can simply slip between the cells.

An intact intestinal lining is therefore the foundation for:

• Efficient nutrient absorption: This is the only way vitamins, minerals, and the like can actually reach the places where they are needed.
• A strong immune defense: It is the bouncer that prevents intruders from entering the body.
• Less inflammation: A tight barrier prevents unnecessary immune reactions that put stress on the body.

Your energy, your skin, your mood—all of these are directly linked to the health of your intestinal lining. It is the quiet hero that tirelessly protects you from within.

When the barrier crumbles: Leaky gut syndrome

But what happens when this protective wall develops gaps? Chronic stress, an unbalanced diet, certain medications, or infections can loosen the tight junctions. The zippers become loose, and the intestinal wall becomes permeable. This condition is also known as leaky gut syndrome, or “leaky gut.”

Suddenly, things can enter your bloodstream that absolutely do not belong there: incompletely digested food components, bacterial fragments, or toxins. Your immune system immediately sounds the alarm, recognizes these particles as foreign, and launches a defensive response. The result is a subtle but persistent inflammation throughout the body.

The consequences of leaky gut are often vague and appear as symptoms that you would not initially associate with the gut:

• New food intolerances: Foods you have always tolerated well suddenly cause problems.
• Chronic fatigue: Your body is constantly using energy to fight the “intruders.”
• Skin problems: Acne, eczema, or rosacea can be triggered by inflammation in the body.
• Joint pain or a general, vague feeling of illness.

A healthy development of the gut is therefore inextricably linked to an intact intestinal wall. If you would like to explore the topic in greater depth, our article tells you everything about the important role of the intestinal barrier for your health.

If you suspect that your intestinal barrier may be weakened, a test such as the mybody®x Gut Health Test can provide clarity. Among other things, it analyzes markers that may indicate increased permeability and inflammation. This gives you a sound basis for taking targeted steps to improve your health.

Your Microbiome: The Trillions of Helpers in Your Gut

After taking a closer look at the protective intestinal wall, we're now zooming in one level deeper—directly into the pulsating life unfolding on it. Welcome to the realm of your microbiome, a gigantic community of trillions of microorganisms that inhabit your gut.

But don't think of this as a loose collection of bacteria. Instead, think of it as a complex, living ecosystem that is just as crucial to your health as any other organ in your body.

These tiny inhabitants are anything but passive freeloaders. They are active partners that take on an incredible range of tasks. They are not only responsible for digestion but also play a central role in the development of the gut and its overall function.

Helpful Allies and Quiet Troublemakers

A vast metropolis of diverse inhabitants lives in your intestines. Most of them should be beneficial, probiotic bacteria. They are the diligent workers tirelessly working to support your well-being.

Their most important tasks include:

• Production of nutrients: They produce essential vitamins, including vitamin K and several B vitamins, which your body cannot produce on its own.
• Energy for your intestinal cells: They convert indigestible fiber into short-chain fatty acids (such as butyrate). This is essentially the favorite food of the cells lining your intestinal wall, keeping them strong and resilient.
• Strengthening the immune system: They train your immune cells and help them distinguish friend from foe. A real fitness center for your defenses.
• Protection against invaders: They occupy the best spots along the intestinal wall, making it very difficult for harmful germs to settle in and cause trouble.

There are also potentially harmful bacteria. In small numbers, they are usually harmless and are easily kept in check by the beneficial bacteria. However, if they become too numerous, they can cause problems by producing toxins or fueling inflammation.

The crucial balance: eubiosis or dysbiosis?

The ideal state of your microbiome has a name: eubiosis. This means there is a healthy balance. A wide variety of beneficial bacteria dominates the ecosystem and keeps the few troublemakers under control. Your gut feels good, your digestion runs smoothly, and your immune system is strong.

But when this sensitive ecosystem gets out of balance, we call it dysbiosis. This is an imbalance in which beneficial bacteria lose ground and harmful species gain the upper hand.

Dysbiosis is often the invisible root of many everyday complaints. It can manifest as bloating, irregular bowel movements, or an irritable bowel sensation, but also as skin problems such as acne, chronic fatigue, or increased susceptibility to infections.

Your lifestyle is the biggest influence on this balance. A one-sided diet high in sugar and fat, chronic stress, lack of sleep, or taking antibiotics can seriously disrupt your microbiome and promote dysbiosis. The good news: you have the power to change it. With a varied, fiber-rich diet, effective stress management, and sufficient sleep, you actively nourish and support your helpful allies.

The composition of your microbiome is as unique as your fingerprint. That is why generic recommendations often fall short. If you would like to delve deeper into the fascinating world of your gut inhabitants, also read our comprehensive article about what the microbiome actually is.

Your microbiome is therefore not an isolated part, but a central player in the development of the gut and your overall health. It is far more than just a digestive aid—it is a protective shield, a nutrient producer, and a trainer for your immune system. To optimally nourish these important partners, a daily intake of around 30 grams of fiber is recommended.

How to find out what is really going on in your gut

Do you feel that something is not quite right in your stomach? Or would you simply like to take proactive steps to support your gut health but do not know where to start? Instead of stumbling in the dark and trying generic advice that may not suit you at all, you can now take a targeted look inside your body.

Modern blood tests and self-tests give you the chance to finally understand what is really happening in your unique body. One of the most revealing methods is a targeted microbiome analysis. It goes far beyond simply observing symptoms and provides hard facts—directly from your body. A test like this can give you the answers you may have been searching for a long time.

Personal insights instead of general tips

Imagine receiving a detailed map of your inner ecosystem. That is exactly what a modern microbiome analysis, such as the mybody®x gut health test, provides. Instead of guessing what your gut is missing, you receive concrete data about the state of your gut flora.

A self-test like this analyzes a tiny stool sample and provides valuable information about the key aspects of your gut health. This includes, for example:

• The diversity of your gut bacteria: Is your microbiome a colorful, stable garden, or does a handful of “weeds” dominate?
• Possible imbalances (dysbiosis): Is there an excess of bacteria that could potentially cause problems and disrupt the balance?
• The presence of important helpers: Are there enough beneficial bacteria that produce, for example, short-chain fatty acids to keep your intestinal lining healthy?
• Signs of inflammation: Certain markers can reveal whether silent inflammatory processes are taking place in your gut that you have not even noticed yet.

With the personalized results of a test, you can finally understand your gut’s specific needs. You can take targeted action that is genuinely right for you instead of wasting time on ineffective methods.

From Knowledge to Action

The true goal of such a test is to give you back control over your health. The results are presented in an easy-to-understand report that not only tells you what is going on, but above all, what you can do now.

Perhaps the test shows that you lack important fiber-digesting bacteria. The recommendation might then be to deliberately eat more resistant starch from cooled potatoes or legumes.

Or it may reveal a lack of bifidobacteria. In that case, fermented foods such as yogurt or kefir could suddenly become real superfoods for you. A blood test for nutrient deficiencies, in turn, can reveal whether your gut is not properly absorbing certain vitamins, providing another important clue.

A test like this transforms the composition of your gut from an abstract concept into your very own health project. You gain a sound basis for actively improving your well-being using data—a crucial step away from vague assumptions and toward genuine clarity.

Your most important gut health questions—answered briefly and clearly

Countless terms and myths circulate around gut health. We are here to shed light on the subject and answer the questions we receive most often—in clear, practical terms and straight to the point.

What is the difference between gut flora and the microbiome?

These two terms are often lumped together, but there is an important difference. Think of it this way: “Gut flora” is an outdated term that essentially refers only to the bacteria in your gut—like one particular type of plant in a garden.

The term “microbiome” is much more accurate and modern. It describes the complete ecosystem in your gut: all microorganisms collectively—not just bacteria, but also viruses and fungi, including all their genes. The microbiome is therefore the entire, living garden with all its inhabitants, not just one part of it.

How quickly can I really improve my gut health?

The good news first: The composition of your microbiome responds surprisingly quickly to positive changes. In just a few days, you can deliberately “feed” and increase your beneficial gut bacteria by consciously changing your diet.

Sustainable results, especially when it comes to rebuilding a strong and resilient intestinal barrier, take a little more time. Here, you should think in terms of weeks or even months. Patience and consistency are the key ingredients for your long-term success.

A healthy microbiome is not a sprint but a marathon. Rapid changes are possible, but stable, resilient gut health develops over time.

Are probiotics always a good idea?

Not necessarily. Probiotics can certainly be very useful, but taking them “blindly” is not always the best solution. Every gut is unique. It’s a bit like hiring a gardener without knowing which plants are missing from your garden or which are already there and simply need care.

A blood test or microbiome analysis can show you precisely which bacterial strains may be underrepresented in your gut or whether there is a nutrient deficiency that needs to be addressed. Sometimes it makes much more sense to use prebiotics (dietary fiber) to specifically support the beneficial bacteria you already have and help them grow.

Can stress really damage the structure of the gut?

Yes, absolutely. Chronic stress is one of the biggest obstacles to a healthy gut structure. Through the so-called gut-brain axis, your brain sends stress signals directly to your abdomen, which can increase the permeability of the intestinal barrier (the so-called leaky gut).

At the same time, stress often changes the composition of your microbiome for the worse and can promote inflammatory processes. A blood test that measures your stress hormone cortisol can show you how much strain your body is under. Stress management is therefore just as important for your gut health as the right diet—both go hand in hand.

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