Written by Raymond Nakamura
Once upon a time (before the Internet), Raymond earned his doctorate studying the hydrodynamics of sand dollars. Nowadays he rents his brain at raymondsbrain.com for writing, cartooning, and thinking, when he is not washing the dishes, walking the dog, or helping his daughter with homework. Follow him on Twitter @raymondsbrain.

Created date

Wednesday, November 17, 2010 - 3:15pm

Why does spinach make my teeth feel funny?

I'm not much of a cook nor a particularly mindful eater, but the funny feeling I get from spinach has given me some food for thought. Do you know what I'm talking about? Not the grit left behind if you don't wash the leaves properly. Some have described the effect as chalky or fuzzy

Turning Over a New Leaf

The most common answer seems to be oxalic acid, also known as ethanedioic acid, which spinach has lots of. Other fruits and vegetables have to a lesser degree. Rhubarb leaves, however, have so much oxalic acid they are considered poisonous. It may have evolved as a way for plants to discourage animals from eating it. 

Crystal Clear?

dentist said the residual feeling was from the oxalic acid combining with the calcium in your saliva, to form crystals of calcium oxalate. But spinach is already has lots of calcium oxalate in the leaves and saliva doesn't seem to have much. I haven't come across any direct experimental evidence to explain the feeling, so I looked for some more corroborating information.

Your Mileage May Vary

The funny teeth syndrome seems to be more associated with cooked spinach than raw, supported by my own anecdotal Facebook survey. Cooking breaks down cell walls so perhaps more oxalic acid or calcium oxalate gets out into your mouth as compared to eating fresh. Also the volume shrinks with cooking, so you would get more spinach mass in a given mouthful. 

Get Into the Kitchen

But cooking may break down oxalic acid. I wonder if calcium oxalate is more stable or even gets formed by cooking. Cooking spinach makes it more nutritious in some ways than eating it raw. I am no dietician, and I'm not going to get into the real and imagined nutritional benefits of eating spinach advocated by Popeye and others. Cooking with calcium-rich foods may also reduce the spinach effect. If anyone has any recipes that tend to reduce the spinach effect on a consistent basis, it might be interesting to see if has chemical components that alters the spinach tooth effect.

Testing, Testing

When I tried to test the spinach effect on myself, the difference between cooked and uncooked was minor. But as I said, I'm not much of a cook nor an especially subtle taster. As well, the amount of oxalic acid can differ by variety of spinach, the age of the spinach, season, and growing conditions. The tip of my tongue is now hurting, though I don't know if eating spinach was necessarily the cause of it. I'll let someone else test that idea on themselves.

So I'm still chewing on this one. I can't decide which explanation to swallow. But at least the next time I discover spinach in my teeth at a job interview, I'll have an excuse — I'm studying the dental effects of oxalic acid and calcium oxalate.


Hi Raymond! I have always

Hi Raymond! I have always experienced the very same thing, my suspicions were that it was the oxalic acid, as I couldnt really think of another food we eat that contains it and as the only other time I get a similar feeling is after eating lemon! Which of course contains another acid, It always felt to me like a thin coat of enamel was getting stripped off my teeth! I decided to just look this up after having spinach for my lunch! :)

I too liken the feeling

I too liken the feeling enamel being stripped off my teeth. As a side note I just ate a spinach salad and paired it with a tasty beer. The feeling on my teeth quickly diminished there after. Perhaps an interaction between the alcohol and acid?

For me, dairy or cream sauces

For me, dairy or cream sauces seem to exacerbate the spinach effect. It could just be the spinach variety or other factors you mentioned.

Last night I ate a meal of

Last night I ate a meal of gnocchi with stracchino cheese sauce and a portion of cooked spinach, washed down with a couple of glasses of wine. The 'furry' effect was so bad that it prompted me to look it up on Google! So there's the calcium and alcohol theories down the drain as far as I go! As I was eating it and experiencing this effect I was wondering if it was the saponins in spinach. My tongue still feels odd this morning!

I had gnocchi with some

I had gnocchi with some sauteed Italian sausage and spinach and got the same effect of a weird coating on my teeth for the first time...good to know I am not crazy for immediately looking it up on google, it seems to be fairly common thing :-)

I have to agree that cooked

I have to agree that cooked is worse than raw and the cream sauces are worst of all. I figured that whatever chemical was responsible, the breakdown of cell walls during cooking made it worse. If calcium has anything to do with it then maybe cream could make it worse? Makes sense to me...

I get the furry feeling from

I get the furry feeling from lots of produce: underripe persimmons and bananas, raw and cooked spinach, even certain baked goods do it to me. I think the baked goods have to do with the baking soda. Would love more info about it as no one else in my family experiences this.

Same here with the persimmons

Same here with the persimmons!! When I first encountered them they were so incredibly delicious, but since I had no idea how to tell whether they're ripe, I then went through a few really appalling experiences and felt like I just couldn't figure them out! I also get a really unpleasant feeling as if I had tiny pins & needles in my tongue from eating kiwis; very sad since I would eat loads of the tasty things if I could, but the acid effect puts in a hard stop after pretty much 1 (sometimes only half!).

The kiwi reaction sounds a

The kiwi reaction sounds a lot like oral allergy syndrome.


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