Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal (GI) disorder affecting millions worldwide. In the United States alone, it's estimated that between 25 and 45 million people are affected by IBS, with women more likely to suffer from it than men. IBS is characterized by recurrent abdominal pain or discomfort associated with altered bowel habits, such as diarrhea, constipation, or a combination of both. While IBS is not life-threatening, it can significantly impact a patient's quality of life. Dietary management has emerged as a crucial tool in alleviating IBS symptoms. This article explores various dietary approaches for managing IBS, emphasizing evidence-based recommendations and practical strategies.
Understanding Visceral Hypersensitivity and IBS
IBS is known as a functional GI disorder, also referred to as disorders of the gut-brain interaction. This means the condition involves how the gut and brain communicate. When this communication is disrupted, it can lead to increased sensitivity in the digestive tract, resulting in uncomfortable symptoms like diarrhea.
It is important to note that people with IBS may have visceral hypersensitivity, which means they have a big reaction to a small amount of stimuli. When two people, one with IBS and one without, eat the same thing, they both may experience the same fermentation by gut microbes. However, the person with IBS will likely experience a more intense reaction.
Several factors contribute to IBS, including gut-brain dysfunction. Identifying and managing triggers is essential for preventing flare-ups.
General Dietary and Lifestyle Recommendations for IBS
As a first-line approach, general advice on healthy eating and lifestyle is recommended in the dietary management of IBS. This includes:
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- Regular Meal Patterns: Adhering to a regular eating pattern can help regulate colonic motility and reduce IBS symptoms.
- Hydration: Daily consumption of 1.5-3 liters of fluids, particularly water and non-caffeinated beverages like herbal teas, is recommended. Carbonated beverages should be avoided.
- Physical Activity: Regular exercise is beneficial for overall health and can positively impact IBS symptoms by enhancing intestinal gas clearance, reducing bloating, and relieving constipation. Mild physical activity is generally recommended, as strenuous exercise may worsen symptoms.
Identifying and Managing Dietary Triggers
A substantial proportion of patients with irritable bowel syndrome (IBS) associate their symptoms with the ingestion of specific foods. Identifying and managing these dietary triggers is crucial for preventing flare-ups.
Alcohol
Alcohol can affect GI tract motility, absorption, and permeability. While evidence linking alcohol directly to IBS is limited, some studies suggest that alcoholic beverages may trigger GI symptoms in susceptible individuals.
Recommendations:
- Assess alcohol intake in relation to GI symptoms to determine if a reduction may alleviate them.
- Consume alcohol in compliance with recommended safe limits, with at least two alcohol-free days per week. Generally, safe alcohol limits are described as no more than 1 drink per day for women and no more than 2 drinks per day for men.
Caffeine
Caffeinated coffee can increase gastric acid secretion and colonic motor activity. While the role of caffeine in IBS is less clear, some studies have indicated coffee and tea as triggers for symptoms in IBS patients.
Spicy Foods
Many IBS patients report that spicy foods trigger GI symptoms like abdominal pain and gastroesophageal reflux. Capsaicin, the active component in red chili, accelerates GI transit and can exacerbate abdominal pain in IBS patients.
Fatty Foods
An important proportion of patients with IBS relate symptoms to foods rich in fat. Duodenal lipids can inhibit small bowel motility and impair intestinal gas clearance, leading to gas retention and bloating.
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Recommendations:
- If related to IBS symptoms during or after eating, fat intake should be assessed, while ensuring the intake is in line with healthy eating guidelines.
Dietary Fiber
The efficacy of fibers in IBS has often been discussed in terms of soluble and insoluble fibers, with the recommendation to increase the intake of soluble fibers and decrease the intake of insoluble fibers, respectively. The role of fibers in IBS remains subject to ongoing debate with a lack of high-quality evidence and contradictory data.
Recommendations:
- A gradual increase in total dietary fiber (naturally occurring and supplemented) to a target dose of 20-30 g/d should be suitable.
- Patients with IBS-C should be recommended to try dietary supplementation of linseeds of up to 2 tablespoons per day, consumed with fluid (150 mL/tablespoon), for a 3 mo trial.
Milk and Dairy Products
Milk and dairy products contain lactose, a disaccharide that is not well digested by an important proportion of adults worldwide. Undigested lactose can lead to GI symptoms.
Recommendations:
- IBS patients should be advised to use a low-lactose diet only if they have a positive lactose hydrogen breath test.
- If they wish to follow a milk-free diet, IBS patients should be informed that there is no high-quality evidence for this diet to improve their symptoms.
The Low-FODMAP Diet for IBS
The most researched dietary intervention for IBS is the low-FODMAP diet. FODMAP is an acronym that represents fermentable carbohydrates (Fermentable, Oligo-, Di-, and Monosaccharides and Polyols). These short-chain carbohydrates are poorly absorbed in the small intestine and rapidly fermented by colonic bacteria, producing gas and attracting water into the intestinal lumen.
Understanding FODMAPs
FODMAPs encompass various types of carbohydrates:
- Fermentable Oligosaccharides: Fructans and galactooligosaccharides (GOS) found in foods like garlic, onions, wheat, and legumes.
- Disaccharides: Lactose found in milk and dairy products.
- Monosaccharides: Excess fructose found in fruits like apples, pears, and honey.
- Polyols: Sugar alcohols like sorbitol, mannitol, xylitol, and isomalt found in some fruits, vegetables, and artificial sweeteners.
How FODMAPs Impact IBS
Due to slow transport mechanisms or ineffective enzymatic activity, FODMAPs are poorly absorbed in the small intestine. Upon ingestion, they remain partially undigested and reach the colon, where they are fermented by the gut microbiota, producing gas and drawing in water via osmotic effects.
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Low-FODMAP Diet Recommendations
Eliminating or restricting dietary FODMAPs will likely benefit those who see a connection between food intake and symptoms such as bloating and pain. A low-FODMAP diet may benefit individuals with the following conditions:
- Irritable Bowel Syndrome (IBS)
- Functional bloating and abdominal distention
- Gastroesophageal reflux disease (acid reflux) with overlapping IBS
- Small intestinal bacterial overgrowth (SIBO), celiac disease, inflammatory bowel disease with overlapping IBS
- Other functional GI diseases
- Individuals with troublesome diarrhea in the presence of an ileal pouch may also benefit from a low-FODMAP diet.
Low-FODMAP Food List
High-FODMAP Foods to Avoid:
- Excess Fructose: Apples, pears, peaches, watermelon, mango, high-fructose corn syrup.
- Lactose: Cow's milk, goat's milk, sheep's milk, yogurt, soft cheeses (ricotta, cottage, cream cheese), ice cream, custard.
- Fructans and/or GOS: Garlic, onion, asparagus, cabbage, leek, artichoke, wheat, barley, rye, chickpeas, lentils, kidney beans.
- Polyols: Apples, pears, apricots, nectarines, peaches, plums, avocado, cherries, lychee, sorbitol, mannitol, xylitol, isomalt.
Low-FODMAP Alternatives:
- Fruits: Oranges, mandarins, kiwifruit, pineapple, strawberries, blueberries, raspberries, grapes, bananas.
- Vegetables: Spring onion (green part), carrots, spinach, potatoes, tomatoes, kale, bamboo shoots, bok choy, celery, ginger, cucumber, eggplant, zucchini, lettuce.
- Milk and Yogurt: Lactose-free milk, rice milk, coconut milk, almond milk, hemp milk, soy-protein milk.
- Cheese: Hard cheeses (brie, camembert, feta).
- Snacks, Bread, and Cereals: Gluten-free bread and crackers, spelt products, sourdough bread, cornflour, corn chips, quinoa, oats, oatmeal, rice, grits, popcorn.
- Garlic/Onion Substitutes: Garlic-infused oil.
- Legumes: Green beans.
- Nuts and Seeds: Peanuts, walnuts, sesame seeds, sunflower seeds, pumpkin seeds.
- Drinks: Orange juice, coffee, sucrose-sweetened or diet soft drinks, red and white wine, gin, whiskey, vodka.
- Sweeteners: Sugar (sucrose), glucose, maple syrup, golden syrup.
- Animal Proteins: Meat (pork, lamb, beef), chicken, turkey, eggs.
- Other: Hard Tofu, tempeh, rice noodles.
Low-FODMAP Diet Phases
- Elimination or Restriction: Restrict or eliminate all FODMAPs for 4-8 weeks to determine their effect on symptoms. Discontinue the diet if symptoms do not improve.
- Reintroduction: After symptom improvement, reintroduce one group of FODMAPs every 2-3 days, gradually increasing the dose and monitoring symptoms.
- Personalization: Maintain symptom control by avoiding only those FODMAPs that trigger symptoms.
Low-FODMAP Diet Downsides & Risks
- Social and lifestyle challenges: the low FODMAP diet is considered more expensive than a usual diet. It also affects some aspects of quality of life, such as social eating.
- Nutritional deficiencies: The most common is fiber deficiency due to low-carb intake. Other possible deficiencies include micronutrient deficiencies such as calcium, iron, magnesium, vitamin B1, vitamin B2, folate (vitamin B9), vitamin B12, vitamin D, and phytochemical deficiencies.
- Dysbiosis (microbiota alterations): Food restrictions may decrease the intake of prebiotics (food for good bacteria), decreasing beneficial gut bacteria strains.
- Constipation due to a limited fiber intake.
- Eating Disorders: the diet may affect the emotional well-being of some individuals.
Gluten-Free Diet for IBS
Many patients with IBS find that wheat or gluten triggers gastrointestinal symptoms, prompting them to exclude these foods from their diets. Several studies have demonstrated that gluten may contribute to symptoms in IBS, even in patients without celiac disease (non-celiac gluten sensitivity), and that at least a subset of IBS patients might benefit from a diet containing no gluten, or a reduced amount.
Probiotics and Synbiotics in IBS Management
A promising adjunct to dietary management is the use of strain-specific probiotics, which may help modulate the gut microbiota in patients with IBS. By reducing gas-producing bacterial species, probiotics could alleviate symptoms associated with carbohydrate malabsorption.
The Importance of Professional Guidance
Implementing dietary changes for IBS is best and most effective with the help of a registered dietitian or GI dietitian for a more modified and individualized diet plan and decreased risk of side effects. A GI registered dietitian will be able to teach you about the elimination phase, as there is more misinformation than accurate information in the ether.
Additional Considerations
- Screening for Disordered Eating: It is important to screen everyone for disordered eating.
- Integrative Team Approach: Create an integrated team for your patient by communicating with their other providers, which may include the gastroenterologist, GI psychologist and pelvic floor therapist, among others.
- Lifestyle Adjustments: Regular exercise, smaller meals, meditation, and smoking cessation can also help manage IBS symptoms.
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