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Our intestinal health is more important than almost anything else. Because our gut determines whether we feel well. Did you know that 80% of your immune system is located in the gut? So it makes sense to support the intestinal flora with its beneficial intestinal inhabitants in a natural way. Read more about intestinal health here and find out tips and tricks on how you can support your health.

What is gut health and why does the intestinal flora matter?

Gut health describes how well the digestive tract breaks down food, absorbs nutrients and protects the body. At its centre is the intestinal flora, also called the gut microbiota or gut microbiome: the community of microorganisms that lives in the digestive tract. An adult weighing 70 kg carries about 38 trillion bacteria, and every person has at least 160 bacterial species in the gut. What this community does for digestion, vitamins and the gut barrier is explained in the guide on why a healthy intestinal flora is so important explains. Because 80% of the immune system is located in the gut, a healthy intestinal flora is considered the most effective way to strengthen the immune system in the long term. Fungi are a normal part of the gut flora as well: yeasts, mainly Candida, live in the gut of about 70% of healthy adults, and problems only arise when intestinal fungus overgrows, for example after antibiotics.

Signs of an unhealthy gut

An irritated gut usually makes itself felt directly in the digestive tract. The seven most common signs are bloating and a swollen belly, excess wind (flatulence), constipation, diarrhea, abdominal pain and cramps, heartburn and a feeling of fullness and heaviness after meals. The guide to digestive problems shows how widespread such complaints are. Irritable bowel syndrome is the collective term for abdominal pain, cramps, flatulence, constipation and diarrhea in which no specific disease can be identified. A gut lining that has become more permeable, popularly called leaky gut, can be measured in inflammatory bowel disease, in coeliac disease and in some people with irritable bowel syndrome. Blood in the stool, unexplained weight loss or fever always need to be checked by a doctor.

Foods for gut health: what helps and what harms

Gut bacteria live on the fiber that the body cannot digest itself. In a meta-analysis of 64 studies, more fiber led to more bifidobacteria and lactobacilli in the stool and higher levels of butyrate, a short-chain fatty acid that gut bacteria produce from fiber. Fermented foods such as yogurt, kefir, sauerkraut and kimchi supply live cultures, and in a 17-week study a diet rich in fermented foods steadily increased the diversity of the gut flora. Fruit, vegetables, nuts and seeds, olives and olive oil and omega-3 fatty acids are also good for the gut; the guide to building up the intestinal flora collects nine practical tips. Heavily processed products, refined cereals, refined oils and fats and above all refined sugar put a strain on the gut: in an animal study, just two days of a high-sugar diet increased gut permeability and reduced the diversity of the gut bacteria, as the article Is sugar bad for the gut? shows.

Probiotics, prebiotics and other nutrients for the gut

Probiotics are live microorganisms that benefit health when they are taken in adequate amounts. Prebiotics are their food, mostly fibers such as inulin and oligofructose, found for example in chicory root, Jerusalem artichoke, garlic, leeks and onions. A product that combines both is called a synbiotic, as the guide to probiotics and prebiotics explains. In chronic constipation, 66% of adults responded to fiber supplements compared with 41% in the control groups, and probiotics increased stool frequency by 1.3 bowel movements per week (constipation in four steps). Digestive enzymes break proteins, fats and carbohydrates down into nutrients the body can absorb; taken with a rich meal, they reduced bloating, gas and fullness afterwards (digestive enzymes). The amino acid L-glutamine is a major fuel for the cells of the intestinal lining and regulates the tight junctions that seal the gut barrier.

Gut, brain, sleep and stress

The gut and the brain constantly exchange signals via the vagus nerve, messenger substances, stress hormones and substances made by gut bacteria; about 80% of the fibers in the vagus nerve carry messages from the gut up to the brain. This network, the gut-brain axis, explains why stress so often hits the stomach and why people with irritable bowel syndrome have about three times the odds of anxiety or depression. The connection works with sleep too: a more diverse gut flora goes hand in hand with higher sleep efficiency and a longer total sleep time, while a lack of sleep can change the composition of the gut flora within just 48 hours (gut and sleep). Research also links the gut and the brain in the long term, from chronic bowel disease and dementia to studies suggesting that in some people Parkinson's disease may start in the gut.

Gut health guides at a glance

• Why is healthy intestinal flora so important? What the gut flora does, what is good and bad for it and how long recovery after antibiotics takes.
• Gut health: tips and tricks The role of gut bacteria, warning signs of declining gut health and four strategies with probiotics.
• 9 tips for building up intestinal flora Fats, fiber, fermented foods and probiotics for a balanced gut flora.
• Probiotics and prebiotics The difference between the two and the foods richest in prebiotics.
• Stopping digestive problems The seven most common signs of an unhealthy gut and five steps to a healthy gut.
• Irritable bowel syndrome Diet, natural remedies and care for the psyche in irritable bowel syndrome.
• Leaky gut syndrome What a permeable gut lining means and what studies show on probiotics, fiber and L-glutamine.
• Gut-brain axis How gut and brain talk to each other and how stress affects digestion.
• Is sugar bad for the gut? How sugar changes the gut flora and the gut barrier.
• Digestive enzymes How proteases, lipases and amylases work and when enzymes are particularly important.
• Heartburn and stomach acid Why stomach acid is not the enemy and which natural measures ease heartburn.
• Flatulence How flatulence develops and when it can be a sign of intestinal illness.

Frequently asked questions

How can I improve my gut health?

Gut health improves with plenty of fiber, a wide variety of plant foods, fermented foods such as yogurt, kefir and sauerkraut, omega-3 fatty acids and probiotics, combined with enough fluids, daily exercise and less sugar and highly processed food. The gut flora reacts to a change in diet quickly, but lasting changes take weeks. More in the guide to building up the intestinal flora.

What are the 7 signs of an unhealthy gut?

The seven most common signs are bloating and a swollen belly, excess wind, constipation, diarrhea, abdominal pain and cramps, heartburn and a feeling of fullness and heaviness after meals. These complaints are widespread: in a global study with 73,076 adults, 40.3% of those surveyed online met the criteria for at least one functional gut disorder such as irritable bowel syndrome. More in the guide to digestive problems.

What are 5 foods good for gut health?

Five good choices are yogurt and kefir with live cultures, sauerkraut and kimchi, chicory root, Jerusalem artichoke, and onions, garlic and leeks. The fermented foods supply live bacteria, while chicory root, Jerusalem artichoke, onions, garlic and leeks are rich in prebiotic fibers such as inulin, which feed the beneficial gut bacteria. More in the guide to probiotics and prebiotics.

How does stress affect the gut?

Stress slows down the vagus nerve and has harmful effects on the gastrointestinal tract and the gut flora. In a Belgian study, simply having to give a public speech made the lining of the small intestine more permeable in volunteers whose cortisol level rose significantly. This is why the gut often reacts to stressful phases with diarrhea, cramps or bloating. More in the guide to the gut-brain axis.

How do antibiotics affect gut health?

Antibiotics act not only against pathogens but also against beneficial gut bacteria. In a study with 12 healthy men, the gut flora returned to near its original composition within 1.5 months after a four-day course, but 9 common species were still undetectable in most participants after 180 days. Taking probiotics together with antibiotics reduced the risk of antibiotic-associated diarrhea by 37%. More in the guide to healthy intestinal flora.