Irritable Bowel Syndrome (IBS) is a chronic functional disorder in the digestive system that can affect any part of the intestine. There is a wide variety of symptoms associated with IBS, including abdominal pain, bloating, gas, diarrhea, constipation, or alternating between both, along with discomfort in the upper abdomen. IBS is highly prevalent across different age groups and populations, and while it can affect daily functioning and quality of life in some cases, it typically doesn't pose short- or long-term health risks. A systematic medical assessment is necessary for diagnosis and to rule out other medical conditions. This document focuses solely on nutritional interventions and does not provide a comprehensive overview of the various treatment options for this syndrome.
The causes of IBS are not fully understood, and in most cases, it's not attributed to a single factor. Nutritional changes can significantly improve symptoms in many cases. When we eat, we consume both the cells of our intestines and a diverse population of gut bacteria (collectively known as the microbiome). A proper diet can alter the natural composition of the intestines and help reestablish the balance between the gut and the microbiome. In many cases, IBS is also linked to stress and anxiety, which can exacerbate symptoms. The intuitive belief (which is mostly correct) that dietary changes might lead to improvements, combined with the placebo effect (feeling better due to the belief in the treatment), often leads to confusion as people avoid various foods and attribute improvements to specific dietary components. Furthermore, just like in inflammatory bowel diseases and even more so, not everything that works for one person will work for another. Some people will see improvements from a diet without simple sugars, others from a gluten-free diet, lactose-free diet, or avoiding fermentable foods that cause gas. For some, the improvement comes from the direct effect of food on intestinal cells or through its influence on the microbiome, while for others, the improvement is a result of avoiding a dietary component that isn't properly absorbed due to genetic variations (as seen in lactose or sucrose intolerance).
Several conditions may cause clinical symptoms similar to IBS but are relatively easy to overcome by avoiding specific foods. Here are three common conditions that, while not falling under the category of IBS, can sometimes appear as such:
Lactose Intolerance (Lactase Enzyme Sub-Activity)
A very common condition that requires special attention. Lactose is a disaccharide found in large quantities in milk and its products and must be broken down in the intestine into monosaccharides (glucose and galactose) for absorption. This disorder is present in about 80% of adults, as the enzyme activity responsible for breaking down lactose decreases with age. Lactose that is not absorbed reaches the large intestine, where it is fermented by bacteria, producing gas and water. The gas causes abdominal pain and bloating, and the water leads to loose stools. Sometimes there are no complaints (since the amount of lactose in an adult diet is usually lower than in children's), while other times there is abdominal pain, gas, or loose stools in combination similar to irritable bowel syndrome.
This is a condition that can cause discomfort but is not dangerous and does not involve any complications. When a person with lactose intolerance consumes foods containing lactose, they may experience symptoms, but it does not usually have long-term consequences. Although lactose intolerance can be diagnosed through a simple breath test, it is also easy to try avoiding all dairy products for two to three weeks while keeping a symptom diary. Improvement is usually significant and immediate. If lactose intolerance is diagnosed, consulting a dietitian is recommended to ensure proper calcium intake, which may decrease due to avoiding dairy products. After improvement, dairy products can be gradually reintroduced to identify one's personal tolerance threshold (which may change over time).
Different individuals are sensitive to different amounts of lactose, and the lactose content varies in different dairy products. Therefore, even with lactose intolerance, there are dairy products that can be consumed. Products like yogurt and hard cheeses contain less lactose than, for example, cottage cheese or whole milk. It's worth noting that after gastrointestinal infections, there might be a temporary decrease in the enzyme that breaks down lactose. In these cases, gradually reintroducing dairy products is recommended. It's possible to add the missing enzyme artificially before consuming lactose, and in some cases, this improves the ability to tolerate lactose.
Lactose intolerance is entirely different from a milk protein allergy. Allergies, which involve a significant clinical impact and require medical supervision, primarily appear in infants and young children (whereas lactose intolerance is rare).
Sucrose Intolerance (Sucrase-Isomaltase Enzyme Sub-Activity)
A similar disorder to lactose intolerance is found in individuals born with a congenital enzyme deficiency responsible for breaking down the disaccharide sucrose, which is found in table sugar and various natural foods, such as fruits. The breakdown (into glucose and fructose) does not occur, sucrose is not absorbed, and it serves as food for gut bacteria, producing gas and water. As a result, complaints can range from severe diarrhea to symptoms similar to irritable bowel syndrome or lactose intolerance.
Gluten Intolerance
Another potential disorder that might manifest similarly to irritable bowel syndrome is sensitivity or non-celiac gluten intolerance. Unlike celiac disease, this condition doesn't involve an autoimmune attack against the gut. The mechanism here isn't yet clear, but it doesn't involve the autoimmune response seen in celiac disease. Unlike celiac disease, the symptoms of gluten intolerance are generally not dangerous in most cases and do not necessarily require treatment unless symptoms are too bothersome. Unlike celiac disease, blood tests and intestinal biopsies are typically normal, so the only way to diagnose gluten intolerance is through a trial period of avoiding gluten for about three weeks while keeping a symptom diary. It's crucial not to start a gluten-free diet before ruling out celiac disease (usually confirmed by blood tests) as it can mask the disease.
Even when there isn't an individual issue with any of the mentioned foods, most individuals with irritable bowel syndrome learn to avoid certain foods. Changing diet and lifestyle are important for managing the syndrome. Restricting certain foods can lead to nutritional deficiencies if not managed properly. Therefore, a comprehensive nutritional assessment and ongoing experimentation are important to identify the connection between food consumption and symptom appearance. It's important to remember that what works for one person might not work for another. This approach can help alleviate symptoms and prevent nutritional deficiencies.
FODMAP Diet
The FODMAP diet is a prominent approach for managing irritable bowel syndrome and has been clinically proven to improve symptoms, particularly gas, and bloating. FODMAP stands for "fermentable oligosaccharides, disaccharides, monosaccharides, and polyols," which are poorly absorbed sugars that can undergo fermentation by gut bacteria, causing abdominal discomfort, gas, and bloating. The FODMAP diet involves avoiding high-FODMAP foods for a certain period and gradually reintroducing them while monitoring symptom improvement.
It's essential to work with a clinical dietitian before starting this diet to prevent nutritional deficiencies. The process involves avoiding problematic foods for a certain period (3 weeks for lactose, and if no response, 3 weeks for gluten, and then 3 weeks for sucrose). Then, gradually reintroducing foods while tracking symptoms. The goal is to identify which foods trigger symptoms and manage the diet accordingly.
Please note that any significant dietary changes should be discussed with a healthcare professional or dietitian, as individual health conditions can vary, and a personalized approach is important for effective management.