I started growing Swiss Chard last year and did so again this year because the chard rolls were such a satisfying discovery. Even though I only have five plants, I was producing more chard than I could use up. This led me to search for the best ways to preserve it, which led me to articles about overconsumption of oxalic acid. Who knew?

The concern about overconsumption of oxalates is the formation of caustic crystals that can cause dis-ease in the human body. In some people, oxalates may contribute to kidney damage, intestinal tract damage (i.e. leaky gut), joint stiffness, arthritis, poor brain function, inflammation or symptoms associated with aging.

As always, information is key. I knew of oxalic acid in rhubarb and spinach, but never really concerned myself about it because we do not eat those very often. But what we do eat is other leafy garden greens, foraged greens, nuts, seeds and beets.

I am now more informed than I was a couple of weeks ago. For what it’s worth, here is my neophyte research on the topic.

I thought these superfoods were good for me!

Why can these nutrient rich foods be hard on the human body? Plants are designed to protect the next generation. This is the same principle as with lectins and phytic acid in nuts and dry beans. (You have probably noticed that I advocate soaking beans or raw nuts for 18 to 24 hours and rinsing before using.)

If you scan a list of high oxalic acid foods, you’ll see that many of them are seeds, even some of the ones that aren’t obvious. Figs? Full of seeds. Kiwi fruit? Ditto. Chocolate? Made from a bean, the seed of the plant.

Balance, moderation, and knowledgeable preparation can made a huge difference.

What should I do?

Learn what foods are high oxalate and pay attention to how often I eat them. Overconsumption is the problem. Make a point of giving my body time to excrete the oxalates before having more.

Lean towards foods with lower oxalic acid content. Almonds are at least six times higher than pecans or walnuts. Black beans are eight times higher than chickpeas.

Eat calcium-rich foods with oxalic acid foods.

Drink lots of water. Oxalic acid is water soluable, so at least some of it can be flushed out of the body.

Cook the higher oxalic acid vegetables – greens, carrots, potatoes, beets – in water and drain well. Contrary to what we learned from our health gurus in the seventies, in the case of these vegetables steaming is not better. In the same surprising way, potato skin or brown rice are not necessarily a better choice since they have higher oxalate content than peeled potatoes or white rice.

Lists and charts

In my reading I found plenty of contradictory information about the oxalic acid content in common foods. After much crosschecking, I’m offering these two lists for comparison, although I think factors such as soaking, method of cooking, likely amount consumed, and so on are missing. I don’t know anyone who eats a huge serving of parsley at one sitting.

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