Oxalates

For a subset of people, high-oxalate “superfoods” can absolutely contribute to or cause real health problems—ranging from painful kidney stones to chronic joint pain, vulvodynia, fatigue, brain fog, and even gut issues.

High oxalate intake + low calcium intake = higher kidney-stone risk.

Oxalates (oxalic acid) are naturally occurring anti-nutrients found in many plant foods. They bind to minerals (especially calcium) and can form sharp crystals.

 

Foods that are extremely high in oxalates (often marketed as “superfoods”):

• Spinach (≈ 600–1200 mg per 100 g raw)
• Swiss chard
• Beet greens and beets
• Almonds and almond milk
• Cashews
• Rhubarb
• Sweet potatoes (moderate-high)
• Dark chocolate/cocoa
• Buckwheat
• Turmeric (very high in some varieties)
• Black tea
• Raspberries, blackberries
• Chia seeds, sesame seeds

For comparison: a single green smoothie with spinach, almond milk, berries, and chia can easily exceed 2000 mg of oxalate—the amount many experts consider the upper safe daily limit for sensitive people.