Walnuts
Serving sizes
Walnuts changes rating with portion size. These are the amounts tested in the literature behind our ratings.
- About 30g
- Larger portions
- Much larger portions
Walnuts are Low FODMAP at 30g, moderate at 31g and high at 36g, from their GOS.
- At 30g, walnuts are Low FODMAP, with only a little GOS.
- At 31g they move to moderate, and at 36g they are high, so GOS climbs quickly once you go past the low serve.
Weigh or count out a 30g portion for a snack or salad topping, and check coated or flavored walnuts for added ingredients.
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Informational only, not medical advice. Individual tolerance varies. Talk to a healthcare professional or a dietitian for personal guidance.
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.
Last reviewed September 22, 2026.