Are all nuts high in oxalate, particularly for individuals with a history of kidney stones?

Are All Nuts High in Oxalate?

No, not all nuts are high in oxalate, but certain specific nuts—including almonds, peanuts, cashews, walnuts, and pecans—are considered high-oxalate foods that should be limited in patients with calcium oxalate kidney stones and hyperoxaluria. 1

Nuts and Oxalate Content

The evidence clearly distinguishes between different types of nuts:

• High-oxalate nuts that require restriction include almonds, peanuts, cashews, walnuts, and pecans 1
• Guidelines specifically list "nuts" as a category to avoid for calcium oxalate stone prevention, alongside spinach, rhubarb, beetroot, chocolate, tea, wheat bran, and strawberries 1
• Not all nuts are created equal in terms of oxalate content, though the guidelines do not specify which nuts are lower in oxalate 1

Clinical Context: When Nut Restriction Matters

Dietary oxalate restriction should only be recommended for patients with documented hyperoxaluria, not all individuals. 2 This is a critical distinction because:

• Only 10-50% of urinary oxalate comes from dietary sources; the remainder is from endogenous metabolism 1
• Up to one-third of calcium oxalate stone formers may experience increased absorption of dietary oxalate (hyperabsorbers) 1, 2
• The bioavailability of oxalate in foods varies significantly, and much may not be readily absorbed 1

Specific Recommendations for Nut Consumption

For patients with calcium oxalate stones and hyperoxaluria: Limit intake of the five specific high-oxalate nuts listed above 1

For patients with primary hyperoxaluria: The most recent 2023 guidelines recommend limiting intake of products containing very high amounts of oxalate, including nuts, but do not recommend a strict low-oxalate diet due to quality of life considerations 1

For general stone formers without documented hyperoxaluria: Complete nut restriction is not necessary 2

Important Caveats

• Only eight foods have been definitively shown to significantly increase urinary oxalate excretion in controlled studies: spinach, rhubarb, beets, nuts, chocolate, tea, wheat bran, and strawberries 3
• A case report documented oxalate nephropathy from excessive consumption of chia seeds (six tablespoons daily) and almonds (five handfuls daily), demonstrating that quantity matters significantly 4
• The increase in urinary oxalate from oxalate-rich foods is not proportional to the oxalate content of the food, suggesting variable absorption 3

Practical Algorithm for Nut Consumption Advice

1. Assess stone history and 24-hour urine oxalate levels 5
2. If urinary oxalate >25 mg/day: Recommend limiting the five high-oxalate nuts (almonds, peanuts, cashews, walnuts, pecans) 1, 5
3. If urinary oxalate is normal: No specific nut restriction needed, but avoid excessive consumption 2
4. Ensure adequate calcium intake (not restriction) to bind oxalate in the gut and reduce absorption 2, 3