Spinach/baking powder-allergy

April 7, 2007 12:03 PM

Is there any chemical link between spinach and baking powder?

I'm (mildly) allergic to both of them and - as far as I know - nothing else. They both give me an unpleasant feeling in the mouth, the palate becomes sort of rough. It doesn't hurt and I haven't started avoiding them, I'm mostly beeing curious about the chemistry/medicin. Any clues? (Until quite recently I thought this was something that happened to everyone, but now I've come to understand that it's more of a personal allergy thing.)

posted by pica to health & fitness (6 comments total)

This page lists the minerals found in spinach. Wikipedia lists the components of baking powder, which are sodium bicarbonate (baking soda) and an acid, typically cream of tartar.

If there's a chemical link between the two, I'm not seeing it.
posted by cerebus19 at 12:45 PM on April 7, 2007

Spinach is high in oxalic acid. Do you get a similar reaction from any of these foods?

Foods that are edible, but that still contain significant concentrations of oxalic acid include - in decreasing order - star fruit (carambola), black pepper, parsley, poppy seed, rhubarb stalks, amaranth, spinach, chard, beets, cocoa, chocolate, most nuts, most berries, and beans. The gritty “mouth feel” one experiences when drinking milk with a rhubarb dessert is caused by precipitation of calcium oxalate. Thus even dilute amounts of oxalic acid can readily "crack" the casein found in various dairy products.

For a quick test you could try chewing a small bit of rhubarb leaf. (Don't eat a whole leaf because that much oxalic acid is poisonous)
posted by MonkeySaltedNuts at 12:56 PM on April 7, 2007 [1 favorite]

If what you are describing is a "chalky" feel to your mouth after eating spinach, it is simply due to the high oxalate content.

Oxalate is an acid salt, there's also acid salts in baking powder (especially in the double acting kind), perhaps you are sensitive to these.

More info about oxalates in spinach, in answer to someone else who wondered why spinach leaves a weird mouth feel.
posted by jamaro at 1:05 PM on April 7, 2007

It doesn't sound like this is the issue, but..

Many people are mildly allergic to raw spinach; normally manifesting as an itchy throat, as far as I know.
posted by Chuckles at 2:29 PM on April 7, 2007

Did you become allergic to them both at the same time?

A molecular similarity isn't the only possible reason for the strangely discreet (and disparate) substances to be allergic to.

It could just come down to your particular HLA class II genotype - your genes, basically. The particular allele(s) you have for the genes encoding MHC II (major histocompatibility complex II) can dictate what you're allergic too.

I recently read a paper which showed one allele to be associated with pollen allergy, and another with peanut allergy (abstract here if you're curious). I don't know which ones are more prevalent in people allergic to spinach or baking soda (I don't think anybody knows yet - I just looked), but it's not too difficult to imagine how someone with the right genetic makeup could have a very particular set of substances they are allergic to without there being a direct molecular link between those substances.

If you're curious about how such genes can dictate what you're allergic to, I'd encourage you to read about the role of MHC II in mounting an immune response. It's complicated stuff though, and you'll have to start by learning about T cells, B cells and antigen presenting cells.

That being said, allergenic crossreactivity is a very real phenomenon (latex and food comes to mind), so I wouldn't necessarily dismiss your idea either - although as others have pointed out, it's difficult to see what the molecular link might be.
posted by kisch mokusch at 11:07 PM on April 7, 2007

thank you guys. i've forwarded the info to my mouth and we'll see what happens.
posted by pica at 10:56 AM on April 11, 2007