← All foods / Vegetables

Leek

High FODMAP

Tested serving

  • 1 leek (83g) High

Leek is High FODMAP, driven by its concentrated Fructans, which land it firmly in high territory even in modest amounts.

  • The Fructans in leek are potent, and like its allium cousins onion and garlic, even a small amount of leek is typically High FODMAP, testing high at 1 leek (83g).
  • Leek is usually used as an aromatic base for soups, stocks, and braises, where its fructans dissolve into the whole dish, so the flavor spreads even when you are not eating large pieces.

For that savory leek note without the fructan load, try the green tops of spring onions or a splash of garlic-infused oil to build a gentle flavor base.

Per 1 leek (83g): 3.32g fructans.

Why leek is rated high

Leek is high FODMAP because of fructans, the same subgroup that puts onion and garlic out of reach. The tested serving, 1 leek (83g), comes in high, and it is the only rung in the published data, so there is no smaller tested amount that has been shown to be low or moderate. Leek is rarely eaten as a side dish anyway: it is usually softened into the base of a soup, a braise or a stock, where the fructans dissolve into the liquid and end up spread through the whole dish even when the pieces themselves are fished out.

What changes your risk

  • Infused oil carries the flavour, not the fructans Fructans are water-soluble and do not dissolve into oil, so garlic-infused or onion-infused oil gives that savoury allium base with none of the fructans, as long as no solid pieces are left sitting in the oil.
  • The green parts are treated differently Leek leaves, the green tops of spring onions and chives all bring an allium note and are handled separately from the leek itself. A pinch of asafoetida in hot oil covers the deeper, onion-like backnote in curries and dals.
  • Fishing the pieces out does not work Once leek has simmered in stock, soup or a braise, its fructans are in the liquid. Straining the solids out leaves the fructans behind in the broth, so a clear soup made on a leek base is still a leek dish.
  • The same problem hiding on a label Onion powder, garlic powder, onion salt, most stock cubes and stock powders, gravy granules, packet soups and the majority of spice and seasoning blends are built on the same fructans. The ingredient list matters as much as what goes in the pan.
  • Stacking across a meal Fructans also come from wheat, rye and barley, so a soup with a leek and onion base served with ordinary bread is stacking several fructan sources in a single sitting.

Swaps

Build the flavour base with garlic-infused oil first, since that does most of the work, then add the green tops of spring onions, leek leaves or chives for the fresh allium note, and a pinch of asafoetida where a dish needs deeper savoury weight. Chopped carrot, zucchini, bell pepper and green beans give body to a soup base, and a homemade stock built on carrot, herbs and plain meat or chicken avoids the commercial cubes entirely. Do not reach for shallot, brown, red or white onion, or the white part of spring onion as a gentler option, because they carry exactly the same fructans. There is no wholesale replacement for a braised leek eaten as a vegetable in its own right, and it is more honest to say so than to point at something risky.

How to lower the load

When shopping, buy spring onions with long green tops and use only the green, and keep a bottle of garlic-infused oil where the olive oil normally sits so it becomes the default for starting a pan. Chives freeze well and can be snipped straight from the bag into soups and eggs at the end of cooking. Read stock, gravy and seasoning labels before the packet goes in the trolley rather than at the stove. Eating out, soups, risottos, pies, casseroles and most gravies are built on a leek or onion base that cannot be removed after the fact, so asking what the dish was started with is more useful than asking for the pieces to be left out.

Common questions

is leek low fodmap

No. Leek is high FODMAP at 1 leek (83g), the serving in the published data, and that is the only amount tested.

can i eat leek on the elimination phase

Leek is high FODMAP at the tested serving of 1 leek (83g), so it is one of the foods usually left out during the elimination phase. Whether it comes back later is worked out with a dietitian during reintroduction.

is the green part of leek ok

Leek leaves are handled separately from the leek itself and are among the usual low FODMAP ways to get an allium note, along with the green tops of spring onions and chives.

what can i use instead of leek in soup

Garlic-infused oil does most of the work, since fructans do not dissolve into oil. Add leek leaves, the green tops of spring onions or chives for freshness, and build the body with carrot, zucchini or green beans instead of a commercial stock cube.

Try FODMAP Foods

Scan any food with your camera, search every rating in this list, and see your safe portion before you eat.

Learn more

What Are FODMAPs? A Plain-English Guide Low FODMAP Elimination Phase: A Week-by-Week Guide FODMAP Stacking: Why You Reacted to 'Safe' Foods How to Read Food Labels on Low FODMAP

Informational only, not medical advice. Individual tolerance varies. Talk to a healthcare professional or a dietitian for personal guidance.

References

  1. Fructan and free fructose content of common Australian vegetables and fruit. Muir et al. (2007), J. Agricultural and Food Chemistry 55(16):6619-6627.
  2. Measurement of short-chain carbohydrates in common Australian vegetables and fruits by HPLC. Muir et al. (2009), J. Agricultural and Food Chemistry 57(2):554-565.
  3. 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.
  4. Dietary sorbitol and mannitol: food content and distinct absorption patterns. Yao et al. (2014), J. Human Nutrition and Dietetics 27(Suppl 2):263-275.
  5. 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.

Last reviewed September 22, 2026.