Monday, September 13, 2010

Oxalic acid in spinach, chard, beet greens

I had combined this info with a recipe on a previous blog post, but am seperating it now so it doesn't seem so convoluted. Apologies for the double post.

I can't get Guy to eat any green vegetables (except, oddly, asparagus every now and then). That's ok, I think what is happening is that he has a very sensitive palate. And I believe this sensitive palate has an evolutionary purpose. The last time we tried to give him spinach he gagged and nearly threw up. I tasted the spinach myself, and though it was exceptionally fresh I detected high levels of oxalates. Oxalic acid is a substance that irritates your tongue and your throat. The sensation can be mild or highly annoying.

Unfortunately, in genetically susceptable people it can also lead to kidney stones.

Oxalates are commonly detected in spinach and chard and I believe other cooking greens (let your palate be your guide--if you notice an irritating sensation in your mouth or throat, that's the oxalates).

Oxalates will also reduce the calcium absorption of the greens. I've read an article that growing conditions will affect the amount of oxalates in plants. This particular article says that if the plant has sufficient ammonia available the oxalic acid is reduced. But what does that mean? Does that mean that you would need more nitrogen? Anyone know?

I've also read that cooking will help break the oxalates down, but to what extent I do not know. I cooked this particular batch of spinach in a spinach lasagne and still detected oxalates, though it wasn't as bad as when fresh.

Anyone out there know any more information?


Mr. H. said...

I have noticed that anytime I plant my Swiss chard in poor soil it does have a strong acid taste to it, the chard in the areas of my garden where the soil is good and rich with composted debris is much better. I never really understood why that was until I read this post of yours.