High-FODMAP Foods and the Low-FODMAP Swaps That Replace Them

What the word FODMAP is actually naming

FODMAP is an acronym, and unpacking it is most of the work: Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols 1Ref 1Monash University, Department of Gastroenterology (2024).About FODMAPs and IBS.The definition of FODMAPs as fermentable oligosaccharides, disaccharides, monosaccharides and polyols, and the estimate that a low FODMAP diet improves symptoms in roughly three in four people with IBS; also that Monash is the originating group and maintains the tested food database.. Each is a carbohydrate the small intestine absorbs poorly. What is not absorbed carries on into the large intestine, where gut bacteria ferment it. Four chemically unrelated groups, one shared fate — which is why foods with nothing culinary in common end up on the same list.

FODMAPs are short-chain carbohydrates that the small intestine absorbs poorly and gut bacteria ferment further down.

That shared fate is the reason the low-fodmap diet groups foods the way it does. Milk and garlic have nothing in common on a plate. They have something in common in a gut. The originating research group at Monash University, which named the acronym, describes a low-FODMAP diet as improving symptoms in roughly three in four people with IBS 1Ref 1Monash University, Department of Gastroenterology (2024).About FODMAPs and IBS.The definition of FODMAPs as fermentable oligosaccharides, disaccharides, monosaccharides and polyols, and the estimate that a low FODMAP diet improves symptoms in roughly three in four people with IBS; also that Monash is the originating group and maintains the tested food database.. That is a strong signal for a dietary change, and it is also the reason the diet is worth doing carefully rather than approximately.

The four groups, in the order they cause trouble for most people:

• Oligosaccharides — fructans and GOS. Nobody digests these. They are a problem of quantity, not of tolerance.
• Disaccharides — lactose. Only a problem if you are short on the enzyme that splits it.
• Monosaccharides — excess fructose. Absorbed well by some people, poorly by others.
• Polyols — sorbitol, mannitol, and their relatives among the sweeteners.

The oligosaccharides: fructans and GOS

This is the group that matters most, because no human digests it. Fructans and galacto-oligosaccharides (GOS) lack the enzyme that would break them down, so they reach the colon intact in everyone — the difference between people is how much a gut protests when they arrive. Fructans live in wheat, rye and barley, and in onion, garlic, leek and artichoke. GOS lives in legumes: beans, lentils, chickpeas, and in cashews and pistachios.

Onion and garlic are the hardest items on the list because they are rarely the food. They are the base underneath the food.

That is the practical problem with this group. Wheat is visible; you can see the bread. Onion and garlic are not — they are in the stock, the sauce, the marinade, the spice blend, the thing the restaurant will not itemise. A week of careful eating can be undone by a stock cube. People working through the high-FODMAP foods to remove usually find that wheat is the easy part and the alliums are the part that takes real attention.

Worth knowing about GOS specifically: it is water-soluble, which is why canned legumes that have been drained and rinsed behave differently from dried ones cooked in their own water. Some of the GOS leaves with the liquid.

Lactose, excess fructose, and the polyols

The other three groups are narrower, and each depends on something about you rather than something about the food. Lactose is milk sugar — a problem only for people whose lactase enzyme has faded, which is most of the world's adults but not all of them. Excess fructose is absorbed well by some people and poorly by others. Polyols vary the same way. So these three groups are not universal the way fructans and GOS are.

Lactose sits in milk, cream, ice cream, and the soft fresh cheeses — ricotta, cottage, cream cheese, halloumi. Aged and hard cheeses lose most of it during ageing, which is why cheddar and parmesan tend not to behave like milk.

Excess fructose is a phrase worth reading precisely. "Excess fructose" means fructose present in excess of glucose, not fructose in large amounts — glucose helps carry fructose across the gut wall, so the ratio is what counts, not the total. That is why apples, pears, mango, watermelon, honey, agave and high-fructose corn syrup appear here, while foods with matched fructose and glucose do not.

Polyols are sorbitol and mannitol, mostly. Sorbitol turns up in stone fruit — peaches, plums, cherries, apricots — and mannitol in mushrooms and cauliflower. Both turn up in the sugar-free aisle, where the sweeteners ending in -ol are the tell: sugar-free gum, mints, and "no added sugar" sweets are concentrated polyol sources that nobody thinks of as food.

Why a printed list can never be the last word

Every list of high-FODMAP foods, including this one, is doing something slightly dishonest: it is reporting a threshold as though it were a property. To call a food "high-FODMAP" is to say that a typical serve of it carries more than a set amount. Change the serve and the label changes with it. This is not a technicality — it is the single most useful thing to understand about the diet.

A food is not high-FODMAP or low-FODMAP. A serve is.

Three things move a food across that line:

• Portion. Many foods on this page are perfectly fine in a small quantity and only become a problem at a full serve. A list cannot tell you which, because a list has no serving size in it.
• Ripeness. A firm banana and a spotted, sweet banana are not the same food chemically. Ripening converts starches to sugars.
• Processing. Traditional long-fermented sourdough has had its fructans worked on by the starter for hours before you ever see the loaf. Lactose-free milk is ordinary milk with the lactase added at the dairy instead of in your small intestine. Draining and rinsing a can of lentils pours some of the GOS down the sink.

Which is why the per-serve numbers live in a tested database rather than in prose. Monash University, the group that defined the acronym and tests the foods, maintains that database as an app 1Ref 1Monash University, Department of Gastroenterology (2024).About FODMAPs and IBS.The definition of FODMAPs as fermentable oligosaccharides, disaccharides, monosaccharides and polyols, and the estimate that a low FODMAP diet improves symptoms in roughly three in four people with IBS; also that Monash is the originating group and maintains the tested food database.. A page like this one is the map of the territory: it tells you which group a food belongs to and therefore what to reach for instead. It cannot tell you where your own line sits.

Swaps that keep the meal intact

The reason the four groups are worth learning is that they make substitution obvious. Once you know what a food is carrying, you are not looking for "a low-FODMAP food" in the abstract — you are looking for something that does the same culinary job without that specific carbohydrate. The swap column below is culinary rather than clinical: it is what people commonly move to, while the tested database is where a serve size gets settled.

The garlic-infused oil swap is the one that surprises people, and it is worth explaining because it reveals the logic. Fructans are sugars, and sugars are water-soluble, not oil-soluble. Steep garlic in oil and the flavour compounds cross into the oil while the fructans stay behind in the garlic, which then gets discarded. You keep the taste and leave the carbohydrate. Nothing else on this list works quite so neatly, but it shows what the swaps are actually doing.

The list is phase one, not a way of eating

Everything above describes a starting point, not a destination, and that distinction is where most self-directed attempts at this diet go wrong. The American Gastroenterological Association describes the low FODMAP diet as the most evidence-based dietary therapy for IBS and delivers it in three phases: a restriction period of roughly four to six weeks, then reintroduction, then personalisation — ideally with a registered dietitian involved 2Ref 2Chey WD, Hashash JG, Manning L, Chang L (2022).AGA Clinical Practice Update on the Role of Diet in Irritable Bowel Syndrome: Expert Review.That the low FODMAP diet is the most evidence-based dietary therapy for IBS and is delivered in three phases — restriction of roughly four to six weeks, reintroduction, then personalisation — ideally with a registered dietitian involved.. The American College of Gastroenterology likewise frames it as a limited trial rather than an indefinite one 3Ref 3Lacy BE, Pimentel M, Brenner DM, Chey WD, Keefer LA, Long MD, Moshiree B (2021).ACG Clinical Guideline: Management of Irritable Bowel Syndrome.That the ACG frames the low FODMAP diet as a limited trial rather than an indefinite way of eating..

The restriction list is a diagnostic instrument with an expiry date. Its job is to end.

Read in that light, the low fodmap diet three phases structure changes what this page is for. The fodmap elimination phase removes the whole list at once, which is a blunt instrument by design — it is trying to establish whether FODMAPs are involved at all, not which ones. That question only gets answered afterwards, when reintroducing fodmaps to find your limits puts the groups back one at a time and watches what happens. The personalised list a person ends up with is almost always considerably longer than the list they started with, because most people react to one or two groups rather than all four.

Staying in restriction because it is working is the common failure, and it is an understandable one — the phase feels like the treatment. A low-fodmap dietitian is the usual way people get through reintroduction without either stalling in phase one or reintroducing everything at once and learning nothing; many now work by video, so an online dietitian for low fodmap diet work is not the geographic problem it once was.

When the list is not the lever

A low-FODMAP trial that does not help is information rather than failure, and the answer to it is not a stricter list. The National Institute of Diabetes and Digestive and Kidney Diseases lists dietary change as one category of IBS treatment among several — alongside fibre, medicines, probiotics, and mental-health approaches including cognitive behavioural therapy and gut-directed hypnotherapy 4Ref 4National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (2017).Treatment for Irritable Bowel Syndrome.That dietary change including the low FODMAP diet is one category of IBS treatment among several — fibre, medicines, probiotics, and mental-health therapies including CBT and gut-directed hypnotherapy.. Diet is one branch of the tree, not the trunk.

This matters because the low-FODMAP diet has a way of becoming the whole conversation. It is concrete, it gives a person something to do, and roughly three in four people with IBS get something from it 1Ref 1Monash University, Department of Gastroenterology (2024).About FODMAPs and IBS.The definition of FODMAPs as fermentable oligosaccharides, disaccharides, monosaccharides and polyols, and the estimate that a low FODMAP diet improves symptoms in roughly three in four people with IBS; also that Monash is the originating group and maintains the tested food database. — all of which makes it easy to keep tightening when it stalls. But a restriction that keeps growing is its own problem: a narrowing diet is harder to eat, harder to enjoy, and harder to sustain, and none of that is measured by whether the symptoms moved.

Anyone weighing up the best diet for ibs is really asking a question that has a per-person answer, and the diet that wins is the one a person can actually live inside. That is the whole point of phases two and three — not to find the most restricted possible list, but the least restricted one that still works.