Back to overview

FODMAP

Table of Contents

What Is FODMAP?
How the Diet Works

What Is FODMAP?

FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These are short-chain carbohydrates that some people cannot digest properly. Instead of being absorbed, they travel to the colon where bacteria ferment them, producing gas and drawing water into the intestine. This causes bloating, pain, and altered bowel habits in sensitive individuals ^[1].

Who Benefits From a Low-FODMAP Diet?

The low-FODMAP diet is specifically designed for people with irritable bowel syndrome (IBS). Research shows that 50-80% of IBS patients experience significant symptom improvement ^[1]. Some people with other digestive conditions like small intestinal bacterial overgrowth (SIBO) or inflammatory bowel disease may also benefit. The diet is not intended for the general population without digestive symptoms.

How the Diet Works

The low-FODMAP approach has three phases. First is elimination: remove all high-FODMAP foods for 2-6 weeks. Second is reintroduction: systematically test individual FODMAP groups to identify your specific triggers. Third is personalization: create a sustainable long-term diet that includes tolerated foods while avoiding only what causes symptoms ^[2].

Common High-FODMAP Foods

Foods to limit during elimination include wheat products, onions, garlic, certain fruits (apples, pears, watermelon), dairy with lactose, legumes, and sugar alcohols like sorbitol and xylitol. Low-FODMAP alternatives include rice, oats, quinoa, carrots, cucumbers, berries, citrus fruits, lactose-free dairy, and firm tofu ^[3].

References

Keep a detailed food-symptom diary

Track everything you eat and your symptoms daily during elimination and reintroduction. This reveals patterns you might otherwise miss and helps identify your specific triggers accurately.

Use garlic-infused oil instead of garlic

The FODMAPs in garlic are water-soluble, not fat-soluble. Garlic-infused oil provides the flavor without the problematic compounds. Make your own by gently heating oil with garlic cloves, then removing the garlic before using.

Focus on green parts of vegetables

The green tops of scallions and chives are low-FODMAP, while the white bulbs are high-FODMAP. Similarly, canned and rinsed chickpeas have lower FODMAP content than dried ones. These small swaps expand your food options.

Reintroduce one FODMAP group at a time

During reintroduction, test only one FODMAP category every 3 days. Start with a small portion on day one, increase on day two, and return to low-FODMAP baseline on day three while monitoring symptoms.

Work with a dietitian experienced in FODMAP

A trained professional can guide you through the phases correctly, ensure nutritional adequacy, and help interpret your results. They also rule out other conditions that might mimic IBS symptoms.

Can the low-FODMAP diet help with conditions other than IBS?

Research is strongest for IBS. Some evidence suggests benefit for small intestinal bacterial overgrowth (SIBO) and certain types of inflammatory bowel disease during flares. People with endometriosis sometimes report improvement. However, the diet has not been proven effective for general bloating without IBS diagnosis, gluten sensitivity, or as a weight loss strategy. Always get proper diagnosis before starting.

Why do portion sizes matter for FODMAP content?

FODMAP effects are dose-dependent. Small portions of high-FODMAP foods may be well-tolerated while larger portions trigger symptoms. For example, 10 almonds are low-FODMAP but 20 are high. One slice of wheat bread may be fine, but two could cause problems. This is why the reintroduction phase tests increasing portions. It is not just about which foods, but how much you eat.

What exactly happens when FODMAPs reach my colon?

When FODMAPs are not absorbed in the small intestine, they travel to the colon where trillions of bacteria ferment them. This fermentation produces gases including hydrogen, methane, and carbon dioxide. Simultaneously, FODMAPs draw water into the colon through osmosis. Together, gas and water stretch the intestinal wall, activating pain receptors in people with sensitive guts. This explains the bloating, pain, and altered bowel movements typical of IBS.

Is a low-FODMAP diet safe long-term?

No, the elimination phase should not continue indefinitely. Long-term restriction reduces gut bacteria diversity and may cause nutritional deficiencies. The goal is to identify your specific triggers, then reintroduce tolerated foods. Most people end up restricting only 3-5 specific foods rather than the entire high-FODMAP list. The personalized phase is meant to be maintained long-term, not the strict elimination phase.