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
