Whole Wheat Bread

High FODMAP

By Michael EisenwasserUpdated October 6, 2026

Serving sizes

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

About 1 slice (30g) Low
Larger portions Moderate
Much larger portions High

Fructans GOS

Whole wheat bread is High FODMAP at a usual serving, though about 1 slice (30g) is low.

At about 1 slice (30g), whole wheat bread is low.
The Fructans and GOS from wheat flour build with each slice, reaching moderate at larger portions and high at much larger portions.
Seeds or extra grains change the texture, but the wheat base is what drives the level.

Keep to about 1 slice (30g), or reach for a certified gluten-free bread when you want a full sandwich.

Why whole wheat bread is rated high

Whole wheat bread is high FODMAP, and the reason is the fructans and GOS that come with the wheat flour it is built from. It is low only at about 1 slice (30g), a single thin slice. Larger portions are moderate, and much larger portions, such as a doorstop sandwich or several pieces of toast, are high. Wholemeal is not a gentler wheat. The bran and the extra grains change the texture and the taste, not the fructans, and the flour is still the bulk of the loaf.

What changes your risk

Serving size The one honest lever on whole wheat bread. About 1 slice (30g) is low, larger portions are moderate and much larger portions are high. A thick bakery slice can weigh well past 30g on its own, so the weight matters more than the count.
A sourdough label A whole wheat loaf sold as sourdough is still a wheat loaf, and the label alone tells you nothing about how it behaves. Judge it by the same serve.
The flour itself Swapping the base is what actually changes the rating. Certified gluten free bread, and breads built on rice, oats, quinoa, buckwheat, polenta or potato, do not carry wheat fructans at all.
Stacking through the day Fructans accumulate. Wheat toast at breakfast, a wheat sandwich at lunch and wheat pasta at dinner is the same group three times over, and onion, garlic, rye and barley add to the same running total. Legumes add GOS to the GOS already in the bread.
Toasting, freezing and staling do nothing Heat does not destroy FODMAPs, and neither does freezing or cooling a loaf. Toast made from whole wheat bread carries the same fructans and GOS the slice started with.

Swaps

For toast, sandwiches, crumbs and anything else a loaf does, certified gluten free bread is the straightforward swap. Beyond bread, rice, oats, quinoa, polenta and buckwheat all fill the starchy base role at a meal, gluten free pasta covers pasta, and a baked potato covers lunch when a sandwich is not happening. Do not reach for rye, barley, wheat couscous, wheat crackers or wheat pita as the lighter option, because they carry the same fructans. Multigrain, seeded, stoneground, sprouted and high fibre wheat loaves are all still wheat loaves.

How to lower the load

When you shop, the words to trust are certified gluten free on the packet, and words like artisan or sourdough on a wheat loaf do not change what it is made from. If you want whole wheat bread, a single thin slice of about 1 slice (30g) is the amount that stays low, so an open sandwich works better than a closed one. Check gluten free labels for inulin or chicory root fibre, which is often added for texture and brings fructans back in through the side door. Gluten free bread stales quickly, so slice the loaf, freeze it flat and toast straight from frozen rather than leaving it out. Eating out, ask for a plain rice or potato side instead of the bread basket, since rolls on the table add up before you have thought about it. Tolerance varies between people, and testing wheat again later is work to do alongside a dietitian.

Common questions

is whole wheat bread low fodmap

Only at a single thin slice. About 1 slice (30g) is low, larger portions are moderate and much larger portions are high, because of the fructans and GOS in wheat flour. Wholemeal is not a gentler choice than white wheat bread.

how much whole wheat bread can i have on a low fodmap diet

About 1 slice (30g) is low. Larger portions are moderate and much larger portions are high, so an open sandwich on one thin slice, or certified gluten free bread, is the more reliable route.

is sourdough bread ok instead of whole wheat

A loaf called sourdough is still made from wheat, so it is judged the same way here. Certified gluten free bread is the more dependable swap for whole wheat.

is whole wheat bread high in fructans

Yes. Fructans from the wheat flour drive the rating, alongside GOS, and they are why the load climbs from low at about 1 slice (30g) to moderate and then high as the portion grows.

Learn more

Where this rating comes from

Whole Wheat Bread 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.