Spring Onion

High FODMAP

Typical portion

Any typical portion High

Fructans

Spring onion is High FODMAP, since the white bulb is a concentrated allium that packs a punch even in small amounts.

The white bulb is loaded with Fructans, which makes the whole vegetable high at any typical portion, and even a small amount stays high.
The green tops are a different story: they carry far less of what drives the bulb high, so many people reach for those instead of the whole stalk.

Stick to the green tops for that oniony flavor, and lean on garlic-infused oil when you want that savory allium depth without the bulb.

Why spring onion is rated high

Spring onion is high FODMAP, and the reason is the fructans packed into the white bulb at the base of the stalk. This rating is inferred rather than measured: it is estimated from what spring onion is made of rather than from a weighed serving in the published data. The portion ladder here records a single rung, Any typical portion, and that rung reads high, so there is no smaller tested amount that comes in lower and no honest way to frame a modest amount of the bulb as a safe choice. Fructans are not broken down by heat either, so softening the bulb in a pan at the start of a dish leaves them in the food and in the sauce around it. The green tops are the genuinely useful part of this vegetable, and they are what the rest of this page is built around.

What changes your risk

Which part of the stalk you use The white bulb is where the fructans concentrate, while the dark green tops carry far less of what drives the bulb high. Cutting where the pale part ends and using only the green is the single change that matters most.
Cooking does not help Frying, roasting, grilling and simmering do not destroy fructans. Boiling the bulb in plenty of water and pouring the water away does remove some, because fructans are water-soluble, but the bulb is a flavour base you keep rather than a vegetable you boil and drain, so this is rarely a real strategy.
Infused oil carries the flavour, not the fructans Fructans dissolve in water, not in oil, so garlic-infused or onion-infused oil gives you that savoury allium depth with none of the fructans, as long as no solid pieces are left sitting in the bottle.
Hidden versions on labels Onion powder, garlic powder, onion salt, onion flakes, stock cubes, gravy granules, most curry pastes and most spice blends are the same fructan problem wearing a different name. Reading the ingredient list matters more here than portioning.
Stacking with other fructan foods Fructans add up across a meal, so the bulb alongside wheat bread, wheat pasta, couscous, garlic or leek bulb builds a load well beyond any one ingredient.

Swaps

Lead with garlic-infused or onion-infused oil, which is the swap that genuinely replaces the role rather than approximating it: use it as the cooking fat at the start of the pan and the dish tastes like it began with allium. For the fresh, sharp finish that raw spring onion gives, use the green tops of spring onions, the green leaves of leek or chives, scattered over at the end. A pinch of asafoetida bloomed in oil gives cooked dishes a savoury base note. What will not work is swapping one allium for another: onion of any colour, shallot, leek bulb and garlic are all driven by the same fructans, and onion or garlic powder is not a gentler version of the fresh thing.

How to lower the load

Buy whole stalks rather than pre-chopped mixed pieces, since pre-chopped packs almost always include the white bulb. At home, lay the stalk out and cut where the pale colour ends, keep the dark green for cooking and discard the bulb rather than tossing it into the stock pot. Green tops keep well upright in a jar of water in the fridge, and they chop and freeze well so there is always some on hand. When buying infused oil, check that the label does not list solid onion or garlic pieces, and if you infuse your own, strain every piece out before storing. Ordering out, the risk is almost never the visible garnish: it is the stock, the marinade and the sauce, so ask what the base is rather than asking them to leave the green bits off the top.

Common questions

is spring onion high fodmap

Yes. Spring onion is rated high FODMAP overall because of the fructans in the white bulb, and the only rung on the tested ladder, Any typical portion, reads high.

can i eat the green part of spring onion

The dark green tops carry far less of what makes the bulb high, and they are a standard low FODMAP way to get oniony flavour. Cut where the pale part ends and use only the green.

does cooking spring onion make it low fodmap

No. Heat does not destroy fructans, so frying, roasting or simmering the white bulb leaves them in the dish. Boiling in plenty of water and discarding the water removes some, because fructans are water-soluble, but that is not how a flavour base is normally cooked.

what can i use instead of spring onion

Garlic-infused or onion-infused oil with no solid pieces left in it, plus the green tops of spring onions, leek leaves, chives or a pinch of asafoetida. Onion powder, garlic powder and stock cubes are not swaps, they are the same fructans on a label.

Learn more

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

Spring Onion is an estimated rating: it is inferred from the food's ingredients and composition and cross-checked, not measured directly in the papers below. The low, moderate and high cutoffs are still those of Varney et al. (2017).

References

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 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. 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.