Quick answer

Garlic, artichoke, shallots, leeks and onions have the most fructans, the fiber family inulin belongs to, at 1.2 to 17.4 g per 100 g in an analysis of 60 vegetables. Wheat supplies about 70 percent of the inulin Americans eat and onions about 25 percent. Fruits carry little, at 0.21 to 0.46 g per 100 g.^1,2

Key facts

Americans get on average 2.6 g of inulin and 2.5 g of oligofructose a day from food, and estimates for Western diets run from 1 to 10 g.^2,3
Among 60 vegetables measured, garlic, artichoke, shallots, leek bulb and onions had the most fructans.¹
In grain foods, fructans per portion as eaten ran from 1.12 g in couscous to none in rice.⁴
Food tables often leave inulin out, because the classic methods for measuring dietary fiber do not pick it up.³
Supplements use inulin extracted from plants such as chicory root, agave and Jerusalem artichoke, which most Americans rarely eat.⁵

The richest vegetables and fruits

Inulin is one of a family of fructans, and food analyses usually report the whole family together. The numbers below are for fructans, so they are the best guide to inulin-rich foods but not a count of inulin alone.^1,3

Among 60 vegetables measured, garlic, artichoke, shallots, leek bulb and onions had the most fructans, the family inulin belongs to, at 1.2 to 17.4 g per 100 g.¹

Fruits carry little. The fruits with measurable fructans, such as white peach, persimmon and melon, had 0.21 to 0.46 g per 100 g.¹

Serving size changes the picture. Garlic is eaten by the clove and artichoke is a side dish, while an onion is often a whole meal ingredient, so the foods at the top of a per-100 g list are not always the ones that add the most to a day.¹

Grains, breads and cereals

Fructans per portion as eaten ranged from 1.12 g in couscous to none in rice, from 0.6 g in dark rye bread to 0.07 g in spelt bread, and from 0.96 g in wheat-free muesli to 0.11 g in oats.⁴

Fructans per portion as eaten, from an analysis of 55 grain foods⁴
Food	Fructans per portion
Couscous	1.12 g
Wheat-free muesli	0.96 g
Dark rye bread	0.6 g
Oats	0.11 g
Spelt bread	0.07 g
Rice	None found

The amounts per portion are small, but grains are eaten several times a day. That is why wheat, not garlic or onions, is the largest single source in the average American diet.²

What an ordinary day supplies

Americans get on average 2.6 g of inulin and 2.5 g of oligofructose a day from food. Wheat supplies about 70 percent of it and onions about 25 percent.²

Estimates of daily intake of inulin and oligofructose in Western diets range from 1 to 10 g, depending on where and how people eat.³

In a 2025 pilot study of 154 healthy school-aged children in the UK, estimated inulin intake from food was a median of 1.3 g a day, and cereal products supplied 58 percent of it.⁶

Set against the trials, an ordinary diet gives a few grams, while the calcium trials used 8 to 10 g a day and the bowel trial 12 g. Food alone is unlikely to reach the amounts that were studied, so the trials gave inulin as an added ingredient.^2,5,7

Inulin added to foods and supplements

Inulin added to foods and supplements is extracted from plants such as chicory root, agave and Jerusalem artichoke. On an ingredient list it may appear as chicory root fiber, oligofructose or fructooligosaccharide, often shortened to FOS.⁵

FOS and oligofructose are the short-chain part of the same fiber, with chains of 2 to 8 units, and they are sweeter and dissolve more easily than long-chain inulin.^8,9

Because the amount is often not printed, a food that lists chicory root fiber tells you inulin is present but not how much. Only the fiber line of a label, which may count it, gives a number.¹⁰

Foods to limit if fructans bother you

The researchers who measured these foods note that fructans can cause digestive discomfort in some people. The foods at the top of the lists above, along with wheat, are the first ones to look at if you notice gas or bloating after eating them.¹

In people with irritable bowel syndrome and similar bowel disorders, a 2019 meta-analysis found that prebiotics did not ease symptoms overall and that inulin-type fructans made flatulence worse. Fructans can cause digestive symptoms in some people.^1,11

Gas is the most common complaint with inulin, followed by bloating. In healthy adults these were mild at 5 to 10 g, and they grew with larger amounts.^12,13,14

Nobody needs to avoid garlic, onions or wheat in general because of inulin. If you have irritable bowel syndrome or another long-term bowel condition, ask your doctor or a dietitian before cutting foods out, since the same foods are also an ordinary source of fiber.^2,11

Questions people ask

Which foods have the most inulin?

Of 60 vegetables measured, garlic, artichoke, shallots, leek bulb and onions had the most fructans, at 1.2 to 17.4 g per 100 g. Chicory root is the source behind most of the trials, and wheat contributes the most to the average American diet.^1,2,5

What is the difference between inulin and FOS?

FOS, also called oligofructose, is the short-chain part of inulin, with chains of 2 to 8 units. Inulin as a whole has longer chains, up to 60 units.⁸

Is it better to get inulin from food or a supplement?

There is no official answer. Food gives a few grams a day, supplement trials used 3 to 20 g a day, and the two have not been compared head to head in the studies we read.^2,15

Which foods high in inulin should I avoid?

Most people need not avoid any. If you get gas or bloating after garlic, onions, artichoke or wheat, or you have a long-term bowel condition, ask your doctor or a dietitian.^1,11

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Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.