Fennel

Low FODMAP

By Michael EisenwasserUpdated October 5, 2026

Serving sizes

Fennel changes rating with portion size. These are the amounts tested in the literature behind our ratings.

About 1 cup sliced (75g) Low
Larger portions Moderate
Much larger portions High

Excess Fructose Fructans

Fennel bulb is Low FODMAP at about 1 cup sliced (75g), with Excess Fructose and Fructans building at larger portions.

Fennel bulb is Low FODMAP at about 1 cup sliced (75g).
Excess Fructose makes larger portions moderate, and Fructans join in at much larger portions, where it is high.
The rating covers the bulb. Fronds and seeds are different parts of the plant.

Shave about 1 cup sliced (75g) into a salad or roast it alongside potato and carrot.

Why fennel is rated low

Fennel bulb is low FODMAP at about 1 cup sliced (75g), enough for a proper shaved salad or a side of roasted wedges. It carries two FODMAPs, Excess Fructose and Fructans, and both build as the pile of slices grows. At larger portions it reads moderate, and at much larger portions it is high. So the bulb is a genuinely useful low FODMAP vegetable, with a clear ceiling.

What changes your risk

How much of the bulb you use About 1 cup sliced (75g) is low, larger portions are moderate and much larger portions are high. Bulbs vary a lot in size, so portion the slices rather than counting bulbs.
Stacking Fructans Fennel shares Fructans with wheat bread, onion and garlic. Fennel and onion braised together, or fennel sausage on a wheat roll, adds Fructans from several sources in one meal.
Stacking Excess Fructose Fennel and apple salad, or a honey glaze on roasted fennel, piles more Excess Fructose onto the same plate.
Cooking water Fructans dissolve in water, so fennel boiled in plenty of water that is then poured away may lose some Fructans. Roasting, grilling and shaving it raw do not remove anything.
Bulb, fronds and seeds These serves cover the bulb. Fronds and fennel seeds are different parts of the plant and are not rated by them.

What else works

For the same crisp, fresh bite in a salad beyond about 1 cup sliced (75g), cucumber, carrot ribbons and bok choy work well, and chives bring a mild allium note without Fructans. For a roasting tray, potato, carrots and zucchini carry the dish. Do not reach for the lookalikes that are not low: leek bulb and onion look and cook like fennel in a braise but are high in Fructans, and a classic fennel and apple slaw adds apple, which is not low.

How to keep it low

Slice the bulb first, then portion about 1 cup sliced (75g) per person before dressing or roasting, since thin shavings are easy to overpile. A mandoline gives paper-thin slices that spread the serving across the plate. Pair it with orange segments, parmesan and olive oil, or roast wedges with potato and a drizzle of garlic-infused oil. Store the untrimmed bulb wrapped in the fridge and cut only what the meal needs.

Common questions

how much fennel is low fodmap

Fennel bulb is low at about 1 cup sliced (75g). It is moderate at larger portions and high at much larger portions.

is fennel high in fructans

Fennel carries Fructans along with Excess Fructose. At about 1 cup sliced (75g) the load is low, and both build until it is high at much larger portions.

does roasting fennel make it lower fodmap

No. Roasting does not remove FODMAPs, because nothing leaves the bulb. The serving size is what keeps it low.

are fennel fronds and seeds low fodmap

These serves cover the bulb only. Fronds and seeds are different parts of the plant and are not rated by them.

Learn more

Where this rating comes from

Fennel is rated from published lab measurements of its FODMAP content, using the low, moderate and high cutoffs of Varney et al. (2017).

Feedback sent through the FODMAP Foods app has led to changes in this list.

See our full rating method →

Sources

Fructan and free fructose content of common Australian vegetables and fruit. Muir et al. (2007), J. Agricultural and Food Chemistry 55(16):6619-6627.
Measurement of short-chain carbohydrates in common Australian vegetables and fruits by high-performance liquid chromatography (HPLC). Muir et al. (2009), J. Agricultural and Food Chemistry 57(2):554-565.
Quantification of fructans, galacto-oligosaccharides and other short-chain carbohydrates in processed grains and cereals. Biesiekierski et al. (2011), J. Human Nutrition and Dietetics 24(2):154-176.
Dietary sorbitol and mannitol: food content and distinct absorption patterns between healthy individuals and patients with irritable bowel syndrome. Yao et al. (2014), J. Human Nutrition and Dietetics 27(Suppl 2):263-275.
FODMAPs: food composition, defining cutoff values and international application. Varney et al. (2017), J. Gastroenterology and Hepatology 32(Suppl 1):53-61. Supplies the low, moderate and high cutoffs used on this page.