Why Does Spinach Make My Teeth Feel Filmy?

What it is about cooked spinach that makes your teeth feel all filmy and icky? This article explains the chemical reaction that creates this annoying side effect—and how to avoid it.

Why Does Spinach Make My Teeth Feel Filmy?

Dear Never Cook Naked Guys: Whenever I eat spinach, cooked or fresh, I get a filmy feel on my teeth. What is that? Is there a trick to cooking spinach to minimize the effect?—Gritted Teeth

Dear Gritted Teeth: You’re worried about teeth that feel filmy? We’re worried about gross green flecks in ours.

Here’s the deal: spinach is high in oxalic acid. When the leaf’s cell walls are broken down, the acid combines with naturally-occurring calcium to make calcium oxalate—essentially, little crystals. Voilà your filmy, gritty teeth.

You have three potential solutions:
1. Wilt spinach quickly over high heat. Do not “cook” it. You’ll still get a little grit, but not as much as (blech) canned spinach.

2. Eat raw spinach. If you chew spinach salad fairly quickly, you don’t have to worry much about this chemical fandango. But keep a toothpick handy to avoid that nasty aforementioned spinach-in-your-teeth situation.

3. Switch greens. Turnip greens, mustard greens, and collards are relatively low in oxalic acid. You can chow down and not worry about film or grit.

Oh, by the way, oxalic acid does one other thing: it inhibits the absorption of iron. Popeye never got as much as he thought. Seems like another reason to switch from spinach to another green to us. Originally published May 14, 2013.

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