Written by Raymond Nakamura
Once upon a time, Raymond earned his doctorate studying the hydrodynamics of sand dollars. Nowadays, when he’s not employed as personal assistant to his lovely and demanding daughter, he enjoys creating fun and educational experiences in science and history using facts and fiction, words, pictures and whatever else is handy. Follow him on Twitter @raymondsbrain

Created date

Wednesday, November 17

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.

Comments

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?

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 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.

I have a feeling this may be

I have a feeling this may be to do with how acidic your own mouth is. I know I have a highly acidic gut and consequently saliva (tested with Ph paper on various occasions!) so perhaps it is this in combination with a high-alkali food like spinach which causes the effect?

Does anyone get this furry

Does anyone get this furry dry mouth feeling from green powder? I've had it for several weeks and am wondering if its the green powder Kyo green that I've been taking?

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