IBS trigger foods: FODMAPs, habits, and finding yours

FODMAPs are short-chain carbohydrates that the small intestine absorbs poorly. They draw water into the gut and are fermented by gut bacteria, which makes gas. In a sensitive gut that can mean bloating, pain, diarrhea, or constipation. The main groups are:

• Fructans, in wheat, rye, onion, and garlic.
• GOS (galacto-oligosaccharides), in beans, lentils, and chickpeas.
• Lactose, in milk, soft cheese, and ice cream.
• Excess fructose, in apples, pears, mango, and honey.
• Polyols, in stone fruits such as cherries and peaches, mushrooms, and sweeteners such as sorbitol and xylitol.

• Large or fatty meals, which can strengthen the gut contractions that cause cramping.
• Coffee and alcohol, which speed up the gut for many people.
• Spicy food.
• Stress and poor sleep. The gut and brain are closely linked, so a hard week can flare symptoms even when your diet has not changed.

The low FODMAP diet, developed at Monash University, is one of the best-studied dietary approaches for IBS. It is not meant to be a forever diet. It has three phases:

1. Reduce. Swap high FODMAP foods for low FODMAP ones, usually for two to six weeks, to see if symptoms settle.
2. Reintroduce. Bring each FODMAP group back one at a time, watching how you respond.
3. Personalize. Keep eating the foods you tolerate and limit only the ones that clearly bother you.

The reintroduction phase only works if you write down what you ate and how you felt, because reactions can come hours later. Our guide to keeping a food and symptom diary covers what to log. A registered dietitian can guide you through all three phases so your diet stays varied and balanced.