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Base foodLow concern
Leafy Greens
In plain words
The short version
Spinach and chard carry oxalates, which lock up their own calcium and iron before the body can reach it.
Why it's green
It's widely considered safe at the amounts used in food, so we mark it green. The Safety section below has the details.
Safety profile
Oxalic acid binds calcium and iron into salts the gut cannot take up, which is why spinach — despite its reputation and its genuinely high iron content — is a poor source of either. Kale, cabbage and broccoli are low in oxalate and their calcium is absorbed well.
The detail
Educational information only. Not medical or dietary advice.