Pesto

High FODMAP

Serving sizes

Pesto changes rating with portion size. Its rating is estimated from what it is made of, so the servings are described rather than weighed.

Small serving Low
Moderate serving High

Fructans GOS

Pesto is High FODMAP at a normal serving, thanks to the garlic and nuts blended right into it.

A small serving stays low, but pesto climbs to high by a moderate serving as the Fructans from garlic and the GOS from pine nuts or cashews build up.
Most jarred and fresh versions lean on garlic as a base flavor, and added ingredients can shift the picture, so a light hand is what keeps it comfortable.

Stir just a small spoonful through pasta or vegetables for that herby flavor, or make your own using garlic-infused oil in place of fresh garlic.

Why pesto is rated high

Pesto is high, and the rating is estimated from what goes into the blender rather than from a weighed serving in the lab. Garlic is a base ingredient in nearly every recipe and jar, and it brings fructans, while the nuts blended in for body bring GOS. The serving data here is qualitative: a Small serving reads low, and by a Moderate serving it is already high, which is where the sauce sits overall. That low rung is the single most useful thing on this page, because it means pesto is usable as a sharp accent rather than a sauce you coat a bowl of pasta with. Blitzing, jarring and heating change none of this, since neither fructans nor GOS are broken down by a blade or by a hot pan.

What changes your risk

Where you sit on the ladder The climb is short. A Small serving reads low and a Moderate serving is high, so pesto stops being a small decision very quickly. Spoon it on and stir, rather than dressing the whole dish from the jar.
Garlic-infused oil in place of garlic Fructans are water-soluble and do not dissolve into oil, so a good quality garlic-infused oil carries the garlic flavour without the fructans, as long as no solid pieces are floating in it. Building your own pesto on infused oil removes the bigger of the two sources.
Which nut goes in Cashews and pistachios are not low FODMAP choices for a homemade batch. Walnuts, macadamias, pecans, peanuts and pumpkin seeds fill the same creamy role, so a homemade pesto can dodge the GOS as well as the fructans.
What is underneath it A Small serving of pesto stirred through wheat pasta brings more fructans from the pasta itself. Serve it over gluten free pasta, rice, potato, zucchini ribbons or green beans so the sauce is the only fructan source on the plate.
Stacking across the meal Fructans and GOS are the two most commonly stacked subgroups in a single sitting. Garlic bread on the side, an onion-based soup to start, or legumes in the salad will push a meal over even when the pesto itself stayed at the Small serving.

Swaps

The most faithful swap is a pesto you make yourself: basil, olive oil, garlic-infused oil, parmesan and walnuts, macadamias or pumpkin seeds, blitzed the same way. It fills the identical role and skips both the fructans and the GOS of the jarred version. When you want the herby lift without any sauce at all, plenty of fresh basil with good olive oil, lemon and parmesan over hot pasta does the job, and chives or the green tops of spring onions add the savoury note people are usually chasing from the garlic. Store-bought pestos that swap basil for another herb are not a way around this, because the garlic and nuts are still in them.

How to lower the load

If you are buying a jar, read the ingredients and expect garlic near the top, then treat what you buy as an accent and keep it at the Small serving the data calls low, spooning it in rather than pouring. Making your own is genuinely easy and gives you both levers at once: use a garlic-infused oil that is clear with no solid pieces suspended in it, pick walnuts, macadamias or pumpkin seeds over cashews and pistachios, and freeze the batch in a flat sheet you can break pieces off so a single portion is what comes out of the freezer. Eating out, pesto is usually pre-made and garlic-heavy, so ask for it on the side and add your own, or order olive oil, parmesan and fresh basil instead.

Common questions

how much pesto is low fodmap

Only the smallest rung comes in low. A Small serving reads low, while a Moderate serving is already high, and pesto's overall rating is high. Use it as an accent rather than as the sauce for a whole dish.

is pesto high in fructans

Yes. Garlic is a base ingredient in most pesto and brings fructans, and the nuts blended in add GOS. Those two together are what put it at high.

can you eat pesto on the elimination phase

A shop-bought pesto is a high FODMAP sauce, so it is not a free choice during elimination. A homemade version built on garlic-infused oil with walnuts, macadamias or pumpkin seeds fits the phase far better.

how do you make low fodmap pesto

Blend basil with olive oil and garlic-infused oil in place of fresh garlic, add parmesan, and use walnuts, macadamias, pecans or pumpkin seeds rather than cashews or pistachios. The infused oil works because fructans do not dissolve into oil.

Learn more

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

Pesto 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.