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Oxalic Acid in Spinach

I often receive questions about oxalic acid, an alkaloid in spinach. It is important to understand that all greens have a small amount of alkaloids, and these alkaloids exist to keep edible plants from being eaten into extinction. Spinach has oxalic acid, lettuce has opiates, kale, chard, cabbage, and parsley all have other kinds of alkaloids. In truth, all plants, even the most edible ones, are a tiny bit poisonous.

Why do plants have alkaloids, you might ask? Imagine if you will a hungry deer grazing on the savanna. This imaginary deer comes upon an imaginary patch of tasty spinach growing nearby that has no alkaloids in it at all and is entirely devoid of oxalic acid. What do you think will happen? Why, the deer will eat every single spinach plant without leaving even one to flower and reseed new spinach plants for the following year! This single lowly deer will have permanently exterminated the entire spinach patch in one fell swoop.

Alkaloids are trace amounts of poison that force us to rotate the plants that we eat, thereby ensuring the survival of the edible plants we routinely consume. When the alkaloids of one plant we have been eating accumulate, we instinctively want to move on and eat something else. In small amounts alkaloids support the immune system by acting like a homeopathic medicine, however, if a person eats only one variety of greens for a long period of time, the alkaloids may accumulate and result in what is known as alkaloid poisoning. The symptoms of alkaloid poisoning manifest as nausea, tingling in the toes and fingertips and in slightly more serious cases, trouble focusing and short-term metal fog.

Alkaloid poisoning is not dangerous, and is actually quite difficult to achieve. I once had alkaloid poisoning after making green smoothies with only kale for six months. That was in fact how I discovered the importance of rotating my greens. After my first six months of green smoothies with kale, I suddenly found that I could not even look at another kale leaf, let alone eat it! I told myself, “this is good for me, I have to drink my smoothie,” but my body could not be fooled by logic. My body was talking to me and it was saying, “No more kale!” I had been wondering why I felt a little numbness in the pinky finger of my left hand, and a thorough internet search uncovered that I was experiencing alkaloid poisoning. I made my smoothie with parsley instead of kale that night, and the next morning the numbness was gone without a trace.

Although somewhat unpleasant, alkaloid poisoning is a fairly mild form of poisoning and does not usually pose any serious threats to your health. The good news is that it is easy to prevent alkaloid poisoning from ever occurring, by simply rotating your greens. For example, on Sunday you might use kale, on Monday spinach, on Tuesday cilantro, on Wednesday lettuce, then kale again, then dandelion greens, then celery, etc. I recommend using at least seven different types of greens in your diet. Try to avoid using one plant more than three times a week. Just to give you an idea of what to strive for, in his book Native American Ethnobotony Daniel Moerman writes that the Native Americans utilized approximately 1,649 species of edible plants each year.

Oxalic acid in food is considered harmful because it can combine with calcium and may leach the body of this important mineral. Yet what I find surprising is that everyone knows about the oxalic acid in spinach, but hardly anyone is aware of the presence of oxalic acid in many other commonly eaten foods such as grains, beans, and especially coffee. While spinach itself is loaded with calcium, which minimizes the loss of this mineral from your body by the oxalic acid, coffee contains no calcium at all. For this reason, it is the oxalic acid in coffee, and not in spinach, that leaches the most amount of calcium from your bones. I would be more concerned about the oxalic acid content in coffee and other products than in spinach. At the same time, even though the oxalic acid content in spinach is minute, if you do not rotate your greens and use only spinach for many weeks, you may accumulate oxalic acid and experience symptoms of poisoning. For this reason, always remember to rotate your greens!