Collagen and the intestinal flora

Collagen and gut flora – the key to hormonal balance and holistic well-being

As we learn more about how the body works as a whole, the gut has emerged as one of the most central organs to our health. Expressions like "the gut is our second brain" are no longer just used in alternative circles – today, science has shown clear connections between the state of the gut and everything from the appearance of the skin to hormone balance, weight regulation, sleep, immune system and even our mental health.

A component often mentioned in connection with skin and joints, but less often in gut discussions, is collagen . But new research suggests that collagen – particularly in the form of hydrolyzed collagen peptides – may play an important role in the structure, function and health of the gut microbiota. In this article, we explore how collagen works in the body, how it affects the gut flora and why this can have far-reaching effects on your health and well-being.

What is collagen?

Collagen is the most abundant protein in the human body and acts as a kind of "glue" that holds together the skin, joints, blood vessels and intestines. There are at least 28 different types of collagen, but types I, II and III are the most studied and most commonly found in dietary supplements.

Collagen is rich in amino acids such as:

• Glycine – important for detoxification, sleep and gut health

• Proline and hydroxyproline – crucial for connective tissue and skin elasticity

• Glutamine – supports intestinal mucosa and immune function

When collagen is taken as a supplement, especially in hydrolyzed form (collagen peptides), it breaks down into amino acids that the body can then use to repair and strengthen tissues – including the gut.

The gut flora: the body's internal ecosystem

Inside your gut live trillions of microorganisms – bacteria, fungi and viruses – which together form what we call the microbiota or gut flora . This flora affects:

• The immune system (70% of the immune system is located in the gut)

• Hormone production (e.g. serotonin and estrogen metabolism)

• Nutrient absorption (including vitamins such as B12, D and K2)

• Weight control

• Skin health

• Mental health and sleep

• Joint health

A balanced gut flora contains a variety of good bacteria like Bifidobacterium and Lactobacillus , which help keep bad bacteria in check, reduce inflammation, and strengthen the intestinal lining. When this balance is disrupted – something called dysbiosis – it can lead to everything from stomach problems to hormonal imbalances and chronic fatigue.

How gut flora affects joint health

We tend to think of joints as something completely separate from digestion, but the fact is that gut flora and joint health are strongly linked through the immune system and inflammation . Here are some of the most important connections:

1. The intestinal flora regulates the immune system

A large part of the immune system (about 70%) is located in and around the gut. A balanced gut flora helps keep the immune system in check so that it does not overreact. If the gut is out of balance (dysbiosis), the immune system can become overactive, which can trigger inflammatory processes that negatively affect the joints – especially in autoimmune joint diseases such as rheumatoid arthritis .

2. Link to low-grade inflammation

Dysbiosis can lead to leaky gut, where the intestinal lining becomes too permeable. This allows bacteria, toxins, and undigested food to pass into the bloodstream and trigger an inflammatory response throughout the body—including the joints. This chronic, low-grade inflammation can lead to pain, swelling, and stiffness in the joints.

3. Bacteria-produced substances affect the joints

Good gut bacteria produce short-chain fatty acids (like butyrate), which have anti-inflammatory properties and can protect both the gut and joints. Studies have shown that people with joint diseases often have lower levels of these beneficial fatty acids in their bodies.

4. The role of intestinal flora in the absorption of nutrients

A healthy intestinal flora helps absorb important nutrients such as:

• Vitamin D – important for bone and joint health

• Magnesium, zinc and omega-3 – all of which are anti-inflammatory. Without the right bacteria, the absorption of these can be impaired, which can weaken the joints' resilience and repair ability.

5. The gut-brain-joint connection

The gut flora not only affects the immune system, but also the central nervous system , which can affect how we experience pain. An unbalanced gut flora can therefore not only cause inflammation – it can also amplify the experience of pain in the joints.

In short:

A healthy gut flora can contribute to:

• Reduced inflammation in joints

• Better immune balance

• Increased absorption of nutrients that support joint cartilage and bones

• Reduced pain response from the nervous system

Collagen and the gut – how are they connected?

1. Strengthens the intestinal mucosa

The intestinal mucosa is a thin but critical barrier that protects the body from harmful substances, while allowing nutrients to pass through. Collagen, especially through its richness in glycine and glutamine , has been shown to strengthen this barrier.

A strong intestinal barrier reduces the risk of leaky gut, a condition in which particles that do not belong in the bloodstream pass through the intestinal lining and trigger the immune system. This can lead to low-grade inflammation, allergies and autoimmune reactions.

2. Favors the environment for good bacteria

Research suggests that collagen peptides act as a form of prebiotics – the nutrients that probiotic bacteria feed on. While collagen is not a classic prebiotic fiber, studies have shown that collagen can:

• Stimulate the production of short-chain fatty acids (SCFAs), such as butyrate , which is crucial for gut health and anti-inflammatory effects.

• Create an intestinal environment with the right pH and nutrient supply for probiotic bacteria to thrive.

3. Reduces inflammation in the gut

Collagen's anti-inflammatory properties, especially via glycine, can help soothe an irritated or inflamed gut, which is common in IBS, Crohn's or ulcerative colitis. When inflammation decreases, the environment for the microbiota improves, allowing good bacteria to flourish.

How does gut health affect the rest of the body?

Improved gut flora and stronger intestinal mucosa have been shown to affect several bodily systems. Here are some examples:

1. Hormonal balance

The gut flora is central to breaking down and recirculating hormones, especially estrogen. An imbalanced flora can lead to estrogen dominance , which is linked to PMS, endometriosis, and acne.

Additionally, up to 90% of the body's serotonin – our "feel-good hormone" – is produced in the gut. A healthy gut environment therefore supports both mood and hormonal balance.

2. Immune system

A diverse and strong gut flora trains the immune system to recognize threats without overreacting. This can reduce the risk of autoimmune diseases, allergies and chronic inflammation.

3. Sleep and stress management

Good bacteria like Lactobacillus rhamnosus have been shown to reduce cortisol levels (the stress hormone) and improve sleep quality. Since collagen also contains glycine , an amino acid that promotes deep sleep, the combination may be extra effective.

Skin health

The condition of the gut affects the skin more than we think. Skin problems like acne, rosacea, and eczema are often linked to dysbiosis or leaky gut. By strengthening the gut barrier and improving the microbiota, collagen can contribute to clearer, smoother skin.

Weight regulation and metabolism

A healthy gut flora helps regulate blood sugar, reduce appetite via the hormone leptin, and break down dietary fiber into energy-giving fatty acids. Studies have shown that a disrupted flora can affect obesity, insulin resistance, and metabolic syndrome.

Joint health and anti-inflammatory effect

Collagen is known to strengthen joints and reduce stiffness – especially type II collagen in osteoarthritis. However, since inflammation in the gut can contribute to joint pain, collagen’s effect on the gut may also have an indirect soothing effect on the joints.

Collagen + Probiotics = Synergistic effect?

Combining collagen with probiotics has become increasingly common in dietary supplements. The idea is to:

• Collagen creates a better "soil" in the intestine

• Probiotics provide the right bacteria

• Together they rebuild the intestinal flora and strengthen the mucosa

Tips for supporting the gut with collagen

Choose hydrolyzed collagen – it is more easily absorbed and provides better effects.

Combine with probiotics and prebiotic fibers – such as inulin or resistant starch.

Avoid an inflammatory diet – sugar, alcohol and processed foods can counteract the effect of collagen.

Give it time – it may take a few weeks before you notice a difference in your stomach, skin and energy.

Conclusion

Collagen is more than a beauty supplement – ​​it is a powerful building block for the entire body, not least the gut. By strengthening the intestinal lining, reducing inflammation and promoting the growth of good bacteria, collagen can create an environment where the microbiota thrives.

A balanced gut flora, in turn, has effects far beyond the walls of the intestine – it affects how we sleep, how we look, how we feel and how our hormones function. By including collagen in your daily routine, preferably together with probiotics and the right diet, you can lay the foundation for a stronger, healthier and more balanced self.