Prof. Dr. med. Sükrettin Güldütuna is a leading figure in the field of gastroenterology and is widely recognized far beyond Frankfurt am Main. As a specialist in diseases of the gastrointestinal tract and the liver, he has earned an excellent reputation through innovative treatment methods and groundbreaking research. The Gastroenterology Clinic in Frankfurt am Main, which Prof. Dr. Güldütuna founded in 1995, is one of the leading outpatient facilities of its kind in Europe.
The clinic offers its patients comprehensive care, ranging from prevention and diagnostics to the most advanced forms of therapy. Under the direction of Prof. Dr. Güldütuna, the clinic ensures high-quality medical care characterized by individualized treatment approaches and state-of-the-art technologies.
Prof. Dr. Güldütuna is a pioneer not only in clinical practice but also in research and teaching. His work has significantly influenced international standards in gastroenterology. Particularly noteworthy is his early introduction of video capsule endoscopy in 2003 and the introduction of the “LiMAx” liver function test in outpatient settings in Europe in 2016. These groundbreaking developments have not only contributed to improved diagnostics but have also opened up new possibilities in patient care.
A significant aspect of his work is research into food intolerances. Prof. Dr. Güldütuna has conducted extensive research on allergies and intolerances and introduced innovative procedures such as confocal laser endoscopy (CLE) in outpatient settings to precisely diagnose and treat these conditions. His expertise also extends to the early detection of cancers of the gastrointestinal tract and the development of new therapeutic approaches.
The high quality of medical care at his clinic is ensured by an experienced team of specialists who are distinguished by their excellent expertise and a high level of dedication. Prof. Dr. Güldütuna has always emphasized comprehensive and specialized care and has ensured that his clinic ranks among the best of its kind. Recognition of his achievements was evident not least in the honorary certificate awarded to him by the City of Frankfurt am Main in 2018 for his outstanding contributions.
Furthermore, Prof. Dr. Güldütuna is highly regarded both in Germany and internationally and has received numerous awards, including honors in Turkey and professorships at universities in Uzbekistan. Prof. Dr. med. Sükrettin Güldütuna thus embodies a unique combination of scientific excellence, innovative research, and dedicated patient care. His work has significantly shaped and advanced the field of gastroenterology not only in Germany but also internationally.
The editorial team of the Leading Medicine Guide had the opportunity to speak with Prof. Dr. Güldütuna and learn detailed information about irritable bowel syndrome and the so-called “leaky gut.”
Irritable bowel syndrome (IBS) and the so-called “leaky gut” are common but complex digestive disorders that affect millions of people. Both conditions cause a wide range of symptoms, such as abdominal pain, bloating, and bowel irregularities, but their causes are not yet fully understood. Stress, dietary factors, and an imbalance in the microbiome play a central role in this. The microbiome—that is, the totality of microorganisms in the gut—is essential for maintaining a healthy intestinal barrier and influences not only digestion but also the immune system.
Irritable bowel syndrome (IBS) is a complex digestive disorder characterized by symptoms such as abdominal pain, bloating, diarrhea, or constipation, without any visible structural changes in the gut.
“Irritable bowel syndrome is a very common diagnosis. Among specialists, as many as 50% of patients present with symptoms suggestive of IBS. All age groups are affected, though an increase is being observed among younger people. As for the causes, about two-thirds of patients have a food intolerance. Why this occurs—even among the relatively large proportion of young people—is relatively unclear. We know that viral infectious diseases can cause irritable bowel syndrome. Other factors can also trigger it. For example, about one-third of patients have heightened sensitivity. Humans have over 100 million nerve cells in the gut, and these are highly sensitive in these patients. “Stress, alcohol consumption, medication use, chronic inflammation, genetic factors, or the so-called ‘leaky gut’ can all play a role,” explains Prof. Dr. Güldütuna regarding the possible causes of irritable bowel syndrome.
The nervous system in the gut is called the enteric nervous system (ENS). It is a complex network of nerve cells that controls digestive processes independently of the central nervous system. It is often referred to as “the second brain” because it contains numerous neurons that regulate digestive processes such as peristalsis, blood flow to the gut, and the secretion of digestive enzymes. The ENS is closely linked to the autonomic nervous system and also plays a role in the interaction between the gut and the brain.
Leaky Gut – when the gut becomes permeable.
Gluten sensitivity, in particular, can lead to damage to the intestinal wall, a condition known as “leaky gut.” This permeable intestine allows harmful substances to enter the bloodstream, which can cause further health problems. Why do some people suffer more from these intolerances than others? The answer lies in several factors. First, genetic predispositions play a crucial role. People who carry certain genes may have a reduced ability to digest certain foods, such as lactose. The microbiome—the community of microorganisms in the gut—also influences how well the body can process food. A healthy microbiome can support digestion and alleviate symptoms, while dysbiosis—an imbalance of microbes—can exacerbate the symptoms.
“We see leaky gut in many patients with irritable bowel syndrome. In this condition, the intestinal cell barrier is compromised, allowing substances such as toxins, bacteria, and undigested food particles to pass through the intestine into the bloodstream. Leaky gut syndrome has not yet been fully researched in medicine, and the exact causes can vary. Leaky gut occurs in many people suffering from acute or chronic intestinal inflammation such as gastroenteritis, Crohn’s disease, or ulcerative colitis. However, factors such as chronic stress, excessive alcohol consumption, certain medications, and a poor diet high in processed foods can contribute to its development. Diagnosing leaky gut is problematic. The diagnosis of “leaky gut syndrome” is controversial within the medical community, as there is no universally recognized diagnostic procedure for it. The lactulose-mannitol test is considered the gold standard. In this test, the person drinks a solution containing lactulose (a synthetic disaccharide) and mannitol (a sugar alcohol), and urine samples are then collected to measure how much of these substances passes through the intestine into the urine. An imbalance in the ratio of these substances may indicate impaired intestinal permeability. This diagnostic test is rarely performed due to the time it takes. The most common diagnostic test performed is the zonulin assay. Zonulin is a substance that is already present in the bloodstream at a certain concentration; it is released by specific signaling molecules and regulates intestinal permeability. Therefore, if there is an increased level of zonulin in the bloodstream, one can assume that intestinal permeability is elevated. “There are certainly other factors that can increase zonulin levels,” explains Prof. Dr. Güldütuna, emphasizing: “We now have a new technology—confocal laser diagnostics—that allows us to directly measure intestinal permeability.”
Confocal laser diagnostics, also known as confocal laser endoscopy, is used, among other things, to diagnose leaky gut by generating high-resolution images of the intestinal mucosa. A special probe equipped with a laser is used to provide detailed images of the intestinal cells in real time. This allows the permeability of the intestinal barrier to be visually assessed, as confocal laser endoscopy enables the structure and function of intestinal cells to be examined at the microscopic level. This helps identify changes in the mucosa that indicate leaky gut.
The Enormous Importance of Bacteria—the Microbiome.
“Leaky gut has been known for years, but has been the subject of intensive scientific research for about 15 years. Whether this phenomenon existed 100 years ago remains unclear. What is certain, however, is that it has become more prevalent in recent years. A disrupted microbiome can contribute to this (the totality of all microorganisms living on and in our bodies, including bacteria, viruses, fungi, and other microbes). A healthy microbiome plays an important role in maintaining gut health and supporting the immune system. For example, we know that certain bacteria—such as those found in probiotics—can be successfully introduced into the gut, a practice often used in patients with irritable bowel syndrome. The microbiome is a great help to the entire body. We currently have 300–500 species of bacteria, and the total number of bacterial cells in the gut amounts to several trillion. About 200–300 years ago, the microbiome also contained many more species of bacteria. For example, approximately 5,000 bacterial species were identified in “Ötzi.” This diversity of bacterial species is very important because they provide enormous support in every way! That is why the microbiome is also called the “second brain.” A growing body of research suggests that these bacteria are not only important for digestion but may also play a role in regulating mood, behavior, and even cognitive functions. This occurs through complex interactions between the gut and the central nervous system. There are bacterial species that release the “happiness hormones” serotonin or dopamine, while others have a major influence on hormonal development. “For example, women going through menopause have a different microbiome because the bacteria also require estrogen to some extent,” explains Prof. Dr. Güldütuna, adding another interesting fact:
“There are long-term studies of competitive athletes in which the bacterium Veillonella atypica—an anaerobic, Gram-negative bacterium—plays a special role and has been detected in increased numbers. This is because this bacterium is capable of breaking down lactic acid, which is produced in large quantities during intense physical activity. By breaking down lactic acid, this bacterium can help stabilize the pH level in muscle tissue and thus delay fatigue. As a result, elite athletes, for example, can run much longer and do not experience muscle soreness. This means that the microbiome adapts to a person’s characteristics; in the case of elite athletes, this specific bacterium can feed on and multiply due to the increased production of lactic acid. If I, as an “average person,” were to ingest this bacterium, I might be able to exercise temporarily without experiencing significant muscle soreness. However, the bacterium would not thrive in my body because I do not produce enough lactic acid. This means that when, for example, a patient is given probiotics, the necessary conditions must be created so that the desired bacteria can feed and multiply. So, when people consume a lot of sweets, artificial sugar products, and fast food, they create unfavorable conditions for the development of a healthy microbiome.”
The microbiome refers to the totality of microorganisms living in and on our bodies, with the gut harboring a particularly large and diverse microbiota. These microbes—including bacteria, viruses, fungi, and single-celled organisms—interact in complex ways with one another and with our bodies. A healthy microbiota supports digestion by helping to break down foods that the human body cannot digest on its own. It produces important nutrients, such as vitamins and short-chain fatty acids, which are essential for the body’s energy supply and the health of the intestinal mucosa. A balanced microbiome also helps regulate the immune system and protects against pathogenic microbes by competing for nutrients and habitat and by producing antimicrobial substances.
Certain foods, particularly hard-to-digest carbohydrates such as FODMAPs, can also exacerbate symptoms.
FODMAPs are a group of short-chain carbohydrates and sugars that are poorly absorbed in the small intestine. The term stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These substances are found in many foods, such as wheat, onions, legumes, dairy products, and some fruits. “In people with irritable bowel syndrome or other digestive problems, FODMAPs can cause symptoms such as bloating, abdominal pain, diarrhea, or constipation. A low-FODMAP diet can often help alleviate these symptoms. The so-called Cell Tolerance Test is a diagnostic procedure used to investigate food intolerances and sensitivities. The most common food intolerances are those to gluten and milk protein. One possible cause is an altered gut microbiota. In addition, the Western population has significantly fewer bacterial species, which can also be attributed to the high consumption of industrially processed foods and the overuse of antibiotics and medications,” explains Prof. Dr. Güldütuna, adding:
“When we treat patients with probiotics, we need to understand the patient’s dietary habits. Dietary changes are usually necessary in these cases. For example, eating a large amount of ‘green stuff’ is definitely beneficial. The good bacteria (most bacteria are good!) like things like parsley, dill, and other herbs. Mediterranean cuisine, for instance, is full of these green herbs. Everyone should take this as a guide.”
The industry recommends inulin as a prebiotic. Inulin is a natural, plant-based dietary fiber found primarily in the roots of plants such as chicory, artichokes, onions, garlic, and many other types of vegetables. Chemically speaking, inulin belongs to the group of fructans, which consist of a chain of fructose molecules. It is often considered a prebiotic fiber because it can promote gut health by serving as food for beneficial bacteria in the microbiome. “What the industry fails to take into account, however, are the varying lengths of the inulin fibers. One type of bacterium requires shorter-chain fibers, while another needs longer ones. That’s why it’s always better to turn to nature to feed the bacteria! It is important to nurture the gut flora with a healthy diet that contains no (or few) preservatives or chlorinated water, and minimal antibiotics,” advises Prof. Dr. Güldütuna.
Irritable bowel syndrome (IBS) is a complex and multifaceted condition that manifests in various subtypes, with symptoms that can vary widely. The main subtypes are IBS with diarrhea (IBS-D), IBS with constipation (IBS-C), and the mixed type (IBS-M), which includes both diarrhea and constipation.
“In IBS-D, frequent, sudden bouts of diarrhea are the primary symptom. These symptoms may be accompanied by abdominal pain, colic, and cramps. Fatigue, skin problems, headaches, and depression also appear among the symptoms. The latter should come as no surprise, since the microbiome can influence our entire emotional well-being. Of course, one can treat all these individual symptoms symptomatically, but unfortunately, this does not address the root cause. A fundamental therapy is needed to stabilize the microbiome. It is also important to distinguish between different types of food intolerances. One type is an allergy, which triggers an immediate reaction to a food—for example, when consuming nuts—but in most cases (over 90%), an intolerance to a food occurs with a delay, sometimes even as late as 72 hours later. “For example, someone with gluten sensitivity (not celiac disease) who follows a gluten-free diet for six months may find that they can tolerate gluten again after those six months,” says Prof. Dr. Güldütuna.
“For patients who present with colicky abdominal pain and diarrhea, laboratory diagnostics are performed. This includes testing for inflammatory markers, an ultrasound (to rule out gallstones), and a gastrointestinal endoscopy. If the results of all these tests are normal, the patient is usually ‘labeled’ as having irritable bowel syndrome. Yet we’ve known for several years now that not all cases of irritable bowel syndrome are the same. This is because when patients simply avoid identified food intolerances, they will experience significant relief until their symptoms disappear completely. It is important to rule out chronic inflammatory bowel diseases using endoscopic diagnostics. Personally, when food intolerance is suspected, I recommend a basic diet consisting of potatoes, rice, olive oil, salt, and water. “If they are symptom-free after a week, then a food intolerance is definitely present. And then the diagnostic process continues,” explains Prof. Dr. Güldütuna, and we’ll conclude the first part of this interview series here.
Thank you very much, Professor Dr. Güldütuna—in our next conversation, we’ll delve deeper into the important aspect of diagnosis!
