Are Walnuts Low FODMAP? Serving Sizes, Benefits, and Nut Comparisons

Walnuts are low FODMAP at 10 halves (approximately 30g) per serving, making them a safe and nutritious snack for people following a low-FODMAP diet. Monash University testing confirms that at this serving size, walnuts do not contain significant amounts of any FODMAP group. However, larger servings can introduce moderate levels of GOS (galacto-oligosaccharides), so portion awareness is important.

Walnuts are particularly valuable on a low-FODMAP diet because they are one of the best plant-based sources of omega-3 fatty acids, which have anti-inflammatory properties that may benefit gut health. They are also rich in protein and healthy fats, making them a satisfying snack that helps fill nutritional gaps common on restricted diets.

What Makes Walnuts Low FODMAP at Standard Servings?

Walnuts are primarily composed of fat (about 65 percent) and protein (about 15 percent), with relatively low carbohydrate content. The small amount of carbohydrate they contain includes some GOS and fructans, but at a 30g serving, these FODMAP compounds are present in amounts below the threshold that triggers symptoms in most people.

The FODMAP content scales with serving size:

Serving Size	Approximate Weight	FODMAP Status	Notes
10 halves	30g	Low FODMAP	Safe for most people
15-20 halves	45-60g	Moderate FODMAP	GOS becomes relevant
25+ halves	75g+	High FODMAP	Significant GOS load

The key FODMAP in walnuts at larger servings is GOS, the same oligosaccharide found in legumes and beans. For people who are sensitive to GOS, exceeding the 30g serving could trigger bloating and gas. During the elimination phase, it is best to stay within the tested safe amount.

How Do Walnuts Compare to Other Nuts?

Not all nuts are created equal when it comes to FODMAPs. Here is how common nuts and seeds stack up:

Nut/Seed	FODMAP Status	Safe Serving	Key FODMAP	Notes
Walnuts	Low FODMAP	10 halves (30g)	GOS at large serves	Excellent omega-3 source
Macadamias	Low FODMAP	20 nuts (40g)	None detected	One of the safest nuts
Pecans	Low FODMAP	10 halves (20g)	None at safe serving	Great for baking
Peanuts	Low FODMAP	32 nuts (28g)	GOS at large serves	Technically a legume
Almonds	Low FODMAP	10 nuts (12g)	GOS/Fructans at larger serves	Small safe serving
Hazelnuts	Low FODMAP	10 nuts (15g)	Fructans at larger serves	Moderate safe serving
Cashews	High FODMAP	Avoid	GOS	High even at small amounts
Pistachios	High FODMAP	Avoid	Fructans/GOS	High even at small amounts
Pine nuts	Low FODMAP	1 tablespoon (14g)	None at safe serving	Great for pesto

Cashews and pistachios are notable for being high FODMAP even at small servings. If a recipe calls for cashews — such as cashew cream in vegan cooking — you cannot simply eat a smaller amount. Instead, substitute with macadamias or walnuts, which provide a similar creamy texture when blended.

Omega-3 Benefits for Gut Health

Walnuts are the richest tree nut source of alpha-linolenic acid (ALA), a plant-based omega-3 fatty acid. A 30g serving provides approximately 2.5 grams of ALA, which is more than the daily recommended intake. While ALA is not as potent as the EPA and DHA found in fatty fish like salmon, research suggests it still offers meaningful anti-inflammatory benefits.

For people with IBS, chronic low-grade inflammation in the gut may contribute to symptom severity. Regular intake of anti-inflammatory foods, including omega-3-rich walnuts, may help modulate the inflammatory response. Walnuts have also been studied for their prebiotic effects — they may promote the growth of beneficial gut bacteria, though more research is needed specifically in IBS populations.

Beyond omega-3s, walnuts provide polyphenols and antioxidants concentrated in their thin, papery skin. Resist the temptation to buy blanched or skinless walnuts, as you would lose these beneficial compounds.

How to Include Walnuts in a Low-FODMAP Diet

As a snack: A handful of 10 walnut halves paired with a low-FODMAP fruit like a small banana or a cup of raspberries makes a balanced, satisfying snack with healthy fats, fiber, and natural sweetness.

In oatmeal: Chop a few walnut halves and sprinkle over your morning oatmeal with a drizzle of maple syrup. This adds crunch, protein, and healthy fats to keep you full through the morning.

In salads: Toasted walnut pieces add texture and nutrition to green salads. Pair with feta cheese (low FODMAP at 40g), mixed greens, and a simple olive oil and lemon dressing.

In baking: Walnuts work well in low-FODMAP muffins, banana bread (using firm bananas), and cookies. Their slightly bitter, earthy flavor complements chocolate and spices like cinnamon.

As a crust: Crushed walnuts mixed with herbs make an excellent crust for baked salmon or chicken — a simple dinner that is completely FODMAP-safe.

Walnut butter: Walnut butter is low FODMAP at about 1 tablespoon (the equivalent fat content of 10 halves). Spread it on sourdough toast or use it in smoothies.

FODMAP Stacking With Nuts

If you eat multiple types of nuts in one sitting, be aware that the GOS content can add up even if each nut is within its individual safe serving. For example, eating walnuts alongside almonds and peanuts in a trail mix means you are combining GOS from three sources. The total GOS load may exceed your tolerance even if no single nut would have been a problem alone.

During the elimination phase, it is wise to stick to one type of nut per meal or snack. During reintroduction and the personalization phase, you can experiment with combinations. Tracking your intake and symptoms with FODMAPSnap can help you identify your personal GOS threshold across mixed-nut scenarios.

Watch Out for Flavored and Coated Walnuts

Plain raw or roasted walnuts are safe, but many commercially available walnut products include problematic additions:

• Honey-roasted walnuts: Honey is high FODMAP due to excess fructose
• Garlic or onion seasoned: Both are high in fructans
• Candied walnuts: May contain high-fructose corn syrup
• Trail mixes: Often include cashews, dried mango, or dried fruit with added honey

The safest approach is to buy plain walnuts and add your own seasoning. A simple home-roasted walnut recipe: toss walnut halves with a teaspoon of olive oil, a pinch of salt, and a sprinkle of cinnamon or smoked paprika. Roast at 175 degrees Celsius (350 degrees Fahrenheit) for 8 to 10 minutes, watching carefully to prevent burning.

Storage Tips

Walnuts are high in polyunsaturated fats, which makes them more prone to going rancid than other nuts. Store shelled walnuts in an airtight container in the refrigerator for up to six months, or in the freezer for up to a year. Rancid walnuts taste bitter and can cause digestive discomfort unrelated to FODMAPs — if your walnuts taste off, discard them.

Key Takeaways

• Walnuts are low FODMAP at 10 halves (30g) per serving
• Larger servings introduce GOS, which may trigger symptoms in sensitive individuals
• Walnuts are the best tree nut source of omega-3 fatty acids
• Cashews and pistachios should be avoided; macadamias and pecans are the safest alternatives
• Choose plain walnuts and avoid honey-roasted, flavored, or coated varieties

Related Articles

• Are Eggs Low FODMAP?
• Honey and FODMAPs: Why Honey Is High FODMAP
• FODMAP Food Guide: What You Can and Can’t Eat

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This article is for informational purposes only and does not constitute medical advice. The low-FODMAP diet should ideally be undertaken with guidance from a registered dietitian experienced in digestive health. Always consult your healthcare provider before making significant dietary changes.