High FODMAP foods are those rich in certain short-chain carbohydrates that your small intestine absorbs poorly. The acronym stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These carbohydrates pass through to your large intestine, where gut bacteria ferment them and produce gases like hydrogen and methane. They also draw extra water into the intestine through osmotic effects. For most people this causes no issues, but if you have irritable bowel syndrome or similar gut sensitivity, the combination of gas and fluid can stretch the intestinal wall and trigger bloating, pain, and diarrhea. A low FODMAP diet reduces symptoms in up to 86% of people with IBS, according to Johns Hopkins Medicine.
Oligosaccharides: Fructans and GOS
Oligosaccharides are chains of sugar molecules found in two main forms: fructans and galacto-oligosaccharides (GOS). Unlike the other FODMAP groups, humans lack the enzymes to break these down at all, so everyone malabsorbs them to some degree. The difference is whether your gut reacts strongly to the fermentation that follows.
Fructans are concentrated in wheat-based foods and certain vegetables. The grain and cereal foods highest in fructans include wholemeal bread, rye bread, rye crispbread, wheat pasta, and muesli containing wheat. On the vegetable side, onion and garlic are the biggest culprits, and even small amounts pack a significant fructan load. That includes powdered forms. If a label lists garlic powder, onion powder, garlic juice, or onion juice, the fructans are still there. Fructans are water-soluble, so when you cook garlic or onion in a soup or broth, the fructans leach into the liquid.
GOS is the dominant FODMAP in legumes and pulses. The highest sources include red kidney beans, split peas, falafels, and baked beans. Chickpeas and lentils also contain meaningful amounts. If beans are a staple in your diet and you’re trying to reduce FODMAPs, this is one of the categories that hits hardest.
Excess Fructose in Fruits and Vegetables
Fructose on its own isn’t automatically a problem. It becomes a high FODMAP issue when a food contains more fructose than glucose, because glucose helps your intestine absorb fructose. When fructose is in excess, the leftover portion sits in your gut and ferments.
The fruits highest in excess fructose include apples, pears, mangoes, watermelon, grapes, cherries, and kiwi. Dried fruits like raisins, dates, and prunes concentrate fructose even further, and fruit juice delivers a large fructose load without the fiber to slow things down. Lychee is another often-overlooked high fructose fruit.
Fewer vegetables fall into this category, but sugar snap peas, sweet corn, tomato paste, and tomato sauce (including ketchup) all contain enough excess fructose to cause trouble at typical serving sizes. The concentration matters: a small amount of fresh tomato is generally lower in FODMAPs than the same tomato reduced into a paste or sauce.
Lactose in Dairy Products
Lactose is the natural sugar in milk, and it requires the enzyme lactase to digest. Many adults produce less lactase than they did as children, which makes lactose a common FODMAP trigger. But not all dairy is equal.
The highest lactose foods include cow’s milk (about 4.7 grams per 100g), sheep’s milk (5.1g), goat’s milk (4.4g), and especially concentrated forms like condensed milk (12.3g) and evaporated milk (12.7g). Dried milk powder tops the list at nearly 53g of lactose per 100g. Yogurt ranges from 3.6 to 4.7g, custard from 4.6 to 5.4g, and rice pudding from 3.9 to 4.9g. Soft cheeses like cottage cheese (3.5g), processed cheese (6.5g), mascarpone (4.5g), and ricotta are also high lactose.
Hard and aged cheeses are a different story. Cheddar, parmesan, brie, mozzarella, and halloumi all contain 0.1g of lactose per 100g or less, because the aging process breaks down most of the lactose. Feta sits slightly higher at 1.4g but is still considered low lactose. If you’re sensitive to lactose specifically, swapping soft dairy for aged cheese or plant-based milks (oat, almond, soy, coconut) can make a big difference.
Polyols: Sugar Alcohols in Food
Polyols are sugar alcohols, primarily sorbitol and mannitol. They occur naturally in certain fruits and vegetables and are also added to sugar-free and “diet” products as sweeteners.
Sorbitol is found naturally in stone fruits like peaches, plums, and cherries, as well as in apples and pears (which also carry excess fructose, making them a double hit). It’s a common ingredient in sugar-free gum, mints, and candies. Mannitol occurs naturally in mushrooms, cauliflower, sweet potatoes, and celery. It also shows up in pineapples, olives, asparagus, and carrots.
Because polyols are poorly absorbed even in healthy guts, they can cause a laxative effect at relatively small doses. If you chew sugar-free gum throughout the day or snack on dried fruit, polyol intake can add up quickly without you realizing it.
Hidden FODMAPs on Food Labels
Some of the trickiest high FODMAP sources aren’t obvious whole foods. They’re ingredients buried in packaged products. Inulin, chicory root, chicory root fiber, and Jerusalem artichoke powder are all concentrated sources of fructans. Food manufacturers increasingly add these to products marketed for gut health, protein bars, high-fiber cereals, and dairy alternatives to boost prebiotic fiber content. Even a small amount of inulin or fructo-oligosaccharides (FOS) contributes significantly to the overall FODMAP load of a product.
The term “natural flavors” on meat and poultry labels can legally include garlic powder, garlic juice, onion powder, and onion juice in the United States. That means a product with no visible garlic or onion in the ingredients list can still contain enough to trigger symptoms. When you’re in the elimination phase of a low FODMAP diet, reading labels carefully for these hidden sources is just as important as avoiding the obvious foods.
Why Portion Size Changes Everything
FODMAP content isn’t black and white. Many foods are low FODMAP at a small serving but become high FODMAP at a larger one. A few tablespoons of canned chickpeas might be tolerable, while a full cup pushes you into high FODMAP territory. The Monash University FODMAP app uses a traffic light system (green, amber, red) to rate individual foods at different serving sizes for exactly this reason.
There’s also a concept called FODMAP stacking. This happens when you eat several foods that are each low FODMAP individually, but together they add up to a high total FODMAP load in one meal. Stacking applies across all FODMAP types, not just within one category. So a meal with a small amount of wheat bread, a serving of soft cheese, and some dried fruit could collectively trigger symptoms even though each item alone would have been fine. The total amount of FODMAPs consumed in one sitting is what determines whether your gut tolerates the meal or not.
Quick Reference by FODMAP Type
- Fructans: wheat bread, rye, wheat pasta, onion, garlic, shallots, inulin, chicory root
- GOS: red kidney beans, split peas, baked beans, falafels, chickpeas, lentils
- Excess fructose: apples, pears, mango, watermelon, dried fruit, fruit juice, honey
- Lactose: cow’s milk, yogurt, cottage cheese, ricotta, condensed milk, ice cream
- Sorbitol: apples, pears, stone fruits, sugar-free gum and candy
- Mannitol: mushrooms, cauliflower, sweet potatoes, celery
Knowing which FODMAP subgroup your trigger foods belong to helps during the reintroduction phase, when you test one group at a time to find your personal thresholds. Most people with IBS don’t react to all five types equally, so the goal is never to avoid every high FODMAP food permanently. It’s to figure out which ones your gut handles and which ones it doesn’t.