What Is A Low Fodmap Diet?

Introduction

A low FODMAP diet is a dietary approach aimed at managing gastrointestinal symptoms, particularly those associated with conditions like irritable bowel syndrome (IBS) and other digestive disorders. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.

This acronym refers to a group of short-chain carbohydrates that are poorly absorbed in the small intestine. FODMAPs are moved to the large intestine/colon, where they are fermented by the gut bacteria. This fermentation results in symptoms such as bloating, gas, abdominal pain and altered bowel habit.¹ 

The primary purpose of a low FODMAP diet is to reduce the intake of these fermentable carbohydrates to prevent digestive discomfort and improve overall quality of life.² This dietary approach starts by slowly eliminating high FODMAP foods from the diet, followed by gradually reintroducing FODMAP foods to identify individual triggers. A low FODMAP diet is useful for symptom management in many people - however, understanding the benefits and challenges can help achieve an optimal transition and outcome. 

What are FODMAPs?

These carbohydrates include various sugars and sugar alcohols found naturally in many foods.² Common examples of high FODMAP foods include:

• certain fruits (e.g. apples and watermelon)
• vegetables (e.g. onions and garlic)
• dairy products (e.g. milk and yoghurt)
• legumes (e.g. beans and lentils)
• sweeteners (e.g. honey and agave syrup)

When consumed, FODMAPs can undergo fermentation by bacteria in the colon, leading to the production of gas and other by-products.² This fermentation process can cause symptoms such as bloating, gas, abdominal pain, diarrhoea and constipation, particularly in individuals with sensitive digestive systems or underlying gastrointestinal conditions. Understanding the role that FODMAPs play in triggering these symptoms can help people manage their diet better, to minimise discomfort and improve their digestive health. 

How does a low FODMAP diet work?

A low FODMAP diet works by systematically reducing the intake of fermentable carbohydrates known as FODMAPs, to alleviate gastrointestinal symptoms.² The diet typically consists of two main phases - the elimination phase and the reintroduction phase: 

Elimination phase

During the elimination phase, high FODMAP foods will be eliminated from the diet for a period of time, usually around two to six weeks. This helps to reduce the overall FODMAP load in the digestive system, giving it a chance to rest and heal. 

Reintroduction phase

After the elimination phase, the reintroduction phase begins, when specific high FODMAP foods are slowly reintroduced, one at a time, while monitoring for any symptoms. This phase helps people identify which FODMAPs trigger their digestive symptoms, allowing for a better understanding of their condition.³ 

It is important to work closely with a registered dietitian during both phases of the low FODMAP diet to ensure proper nutrition. While the elimination phase can provide temporary relief from symptoms, the ultimate goal of the diet is to reintroduce as many foods as possible while still maintaining symptom control. This requires careful attention to portion sizes and individual tolerance levels. 

Conditions managed by a low FODMAP diet

A low FODMAP diet is primarily used to manage gastrointestinal symptoms associated with conditions such as irritable bowel syndrome (IBS) and other digestive disorders. IBS is a common gastrointestinal disorder characterised by symptoms such as:

• abdominal pain
• bloating
• gas
• diarrhoea
• constipation

Research has shown that FODMAPs can increase symptoms in individuals with IBS, making a low FODMAP diet an effective dietary intervention for symptom management.⁴ Additionally, other digestive disorders, such as inflammatory bowel disease (IBD), small intestinal bacterial overgrowth (SIBO) and functional gastrointestinal disorders, may also benefit from this diet. These conditions are often associated with similar gastrointestinal symptoms that can be triggered or worsened by FODMAP consumption. 

It is important to note that a low FODMAP diet is not a cure for these conditions but rather a tool for managing symptoms and improving gastrointestinal health. Consulting with a healthcare professional, such as a registered dietitian, is essential for proper diagnosis, guidance and use of a low FODMAP diet for optimal outcomes.⁵

Benefits and challenges of a low FODMAP diet

Following a low FODMAP diet offers several potential benefits for individuals with gastrointestinal symptoms, particularly those with conditions such as IBS. By reducing the intake of fermentable carbohydrates, individuals may experience relief from symptoms such as bloating, gas, abdominal pain and altered bowel habits. For many people, switching to a low FODMAP diet can improve their overall quality of life, allowing them to engage in daily activities without experiencing uncomfortable symptoms.⁶

However, while a low FODMAP diet can be effective in symptom management, it also has certain challenges and limitations. One of the main challenges is the restrictive nature of the diet, which requires eliminating or severely limiting many foods that are commonly consumed.⁶ This can make meal planning and dining out more challenging and may require individuals to carefully read food labels and ingredient lists to check for high FODMAP ingredients. 

Additionally, the reintroduction phase of the diet can be complex and time-consuming, as it involves carefully reintroducing specific FODMAP-containing foods to identify individual triggers.⁶ This phase requires patience, diligence and close monitoring of symptoms, which can be difficult to manage. Despite these challenges, many people find that the benefits of symptom relief outweigh the challenges of following the diet. 

What can you eat on a low FODMAP diet?

When following a low FODMAP diet, individuals are encouraged to focus on consuming foods that are low in fermentable carbohydrates while avoiding those that are high in FODMAPs.⁷ 

Low FODMAP foods 

• Strawberries
• Blueberries
• Oranges
• Grapes
• Spinach
• Carrots
• Bell peppers
• Courgettes
• Chicken
• Turkey
• Fish
• Eggs
• Tofu
• Rice
• Quinoa
• Oats
• Gluten-free bread and pasta
• Lactose-free alternatives e.g. lactose-free milk, yoghurt and hard cheese

High FODMAP foods

• Apples
• Cherries
• Mangoes
• Watermelon
• Onions
• Garlic
• Cauliflower
• Mushrooms
• Beans
• Lentils
• Chickpeas
• Soy products
• Milk
• Soft cheeses
• Ice cream
• Honey
• Agave syrup
• High-fructose corn syrup

Paying attention to food labels and ingredient lists can help individuals make informed choices about which foods to eat and which foods to avoid. 

Tips for following a low FODMAP diet

Working with a registered dietitian

Consulting with a registered dietitian who specialises in digestive health is crucial for proper guidance and support when following a low FODMAP diet. A dietitian can help create personalised meal plans, provide education on FODMAPs, assist with food reintroduction and address any concerns or questions that may arise throughout the process.

A low FODMAP diet is typically not intended for long-term use. While it can be effective in managing gastrointestinal symptoms in the short term, prolonged restriction of FODMAPs may lead to nutritional deficiencies and imbalances in the gut microbiota.⁸

Reading food labels and ingredient lists

When grocery shopping, carefully read food labels and ingredient lists to identify high FODMAP ingredients and avoid products that may trigger symptoms. Look for terms such as ‘fructose’ ‘lactose,’ ‘polyols’ and ‘galacto-oligosaccharides’ on labels, as these indicate the presence of FODMAPs.

Meal planning and recipe modification

Plan meals ahead of time and focus on incorporating low FODMAP foods into the diet. Explore recipe modifications and substitutions to create delicious and satisfying meals that follow the low FODMAP guidelines. There are many resources available, including low FODMAP cookbooks and websites, that offer recipe ideas and inspiration.

Summary

A low FODMAP diet is a helpful way to manage gastrointestinal troubles, especially for people with conditions such as irritable bowel syndrome. By cutting down on certain types of carbohydrates known as FODMAPs, many people find relief from symptoms like bloating, gas and abdominal pain. While this diet can make a significant difference in symptom management, it is not always easy.

Working out what foods to eat and what foods to avoid can be challenging, and it takes time to find out which foods trigger symptoms - but with proper guidance from a dietitian and a good understanding of how the diet works, many people are able to successfully adapt. It is important to keep in mind that this diet is not suitable for everyone, so it is essential to consult a healthcare provider before changing diets to decide if it is the best option.