Do Greens Harm or Help Your Health?

Many people are afraid of eating too many greens because they have heard the possible dangers of consuming too much oxalic acid. Greens, like certain plant foods, are high in oxalic acid.

You might already guess my stance on this controversy, but just in case there is any confusion, I will spell out my personal reaction to these concerns at the end of this post.

The Problem:

1. Oxalic acid binds with some nutrients, making them inaccessible to the body. To eat large amounts of high oxalic foods over a period of weeks to months may result in nutritional deficiencies, most notably of calcium.

2. Oxalic acid is associated with the formation of kidney stones. If you have kidney problems, your doctor may advise you against eating foods with high levels.

3. Oxalic acid poisoning symptoms include weakness, burning in the mouth, cardiovascular collapse, burning in the throat, abdominal pain, nausea, vomiting, diarrhea, convulsions, and coma.

4. Individuals with gout, rheumatoid arthritis, or certain forms of chronic vulvar pain are advised to avoid foods high in oxalic acid or oxalates.

Next page: Are these problems reasonable? What are the benefits?

Is This Possible? The Murky Middle

  • Oxalic acid is a naturally occurring substance in plants, animals, and humans.
  • I often think that anything with the word acid in it will scare people, but not all acids are bad. Remember that Omega-3s, which everyone is currently trying to put into their bodies, is an essential fatty acid. (That might be a bad example, of course, since everyone is also scared of the word ‘fat’.)
  • Rhubarb contains high amounts of oxalic acid. If your weight is 145 pounds, you would have to consume about 25 grams of pure oxalic acid to cause death. That means you would have to eat about 11 pounds of rhubarb!
  • Other foods that contain significant amounts of oxalic acid (in order from highest to lowest amounts): buckwheat, starfruit, black pepper, parsley, poppy seed, rhubarb stalks, amaranth, spinach, chard, beets, cocoa, chocolate, most nuts, most berries, and beans. If you really had to avoid oxalic acid, that would be difficult.
  • There is a theory that cooking greens will lower the oxalate content, but food chemistry studies show that blanching or boiling of green leafy vegetables does not make a significant difference. Thus, green smoothies do not have more oxalic acid in them, contrary to some thought.

Benefits and Rebuttals: The Other Side of the Oxalic Acid Story

1. It has been assumed that, due to its high oxalate content, black tea increases kidney stone formation—but recent research has shown it to have a preventive effect.

2. Victoria Boutenko of the Raw Food Family site did research on how high oxalic acid foods actually reduce the formation of kidney stones. The true cause of kidney stones is not oxalic acid, but is actually animal protein.

3. Oxalic acid is linked to the cure or prevention of cancer:

  • When cancer is diagnosed, there is always a low level of oxalic acid in the blood. It is important to have enough oxalic acid in our blood because this eliminates abnormal cells without harmful side effects.
  • Every alternative cancer cure that is successful is filled with foods, herbs, grasses, and teas that are full of high amounts of oxalic acid.
  • The American Cancer Society conducted tests over 50 years ago using oxalic acid in the treatment of cancer, and the results in papers and evidence were positive.
  • “When oxalic acid is in our blood; in foods & beverages we eat and drink, and testimonials confirm oxalic acid kills cancer cells, virus, bacteria, and decalcifies the material in plaque in arteries; and is in the blood of all warm blooded mammals.” (From booklet Questions and Answers About E- M- F, Electric and Magnetic Fields Associated with the Use of Electric Power.)
  • Radiation treatment decomposes oxalic acid in the blood. This usually weakens the immune system, so the body is unable to fight off viral or bacterial disease. This is this why many cancer patients die from cancer related to viral pneumonia.


Next page: More benefits, and my own opinion.

4. Oxalic acid is needed by our body. It is important for colon health. When we do not get enough from our diet, the body makes it from ascorbic acid.

5. Eating foods containing oxalates and calcium together may reduce the risk of stones, according to some studies, because oxalate binds with calcium in the intestine.

6. All the foods high in antioxidants are also high in oxalic acid.

7. Some of the healthiest foods on the planet are high in oxalic acid.

Even if you could avoid these foods, you would not want to!

Plant foods with high concentrations of oxalic acid (over 200 ppm) include (but are not limited to): lamb’s-quarter, buckwheat, starfruit, black pepper, purslane, poppy seeds, rhubarb, tea, spinach, plantains, cocoa and chocolate, ginger, almonds, cashews, garden sorrel, mustard greens, bell peppers, sweet potatoes, soybeans, tomatillos, beets and beet greens, oats, pumpkin, cabbage, green beans, mango, eggplant, tomatoes, lentils, and parsnips. (From the USDA)

My Own Personal Opinion

  • Before you start limiting greens, nuts, buckwheat, and cabbage … totally eliminate junk food … and fast food, packaged food, microwaved food, white sugar, and white flour.
  • Most people need to eat more greens, not less.
  • I love my green smoothies for breakfast; they taste good and are filled with so much nutrition.
  • One of the great things about greens are that they are alkaline-forming and many of us are way too acidic. I recommend this in all my health coaching and Healthy Weekend Web Bootcamps.

Here are a few powerfoods high in oxalic acid. You can read about their many benefits:



heather g
heather g9 months ago

I don't think anyone would be eating greens exclusively, so shouldn't be a concern.

Richard B.
Past Member about a year ago


Cosmic Sky
Sky Price3 years ago


Roderick D.
Roderick D5 years ago

Thanks for making me confused. you've just told me that oxalic acid is bad for me/good for me. You've just listed all the stuff I eat every day and that they are high in oxalic acid. Then you tell me that if I suffer from gout - thanks to incompetent doctors prescribing the wrong medication I do - I shouldn't ingest oxalic acid - I know it forms crystals in the joints. So pray tell what the Mary Ellen am I supposed to do about oxalic acid foods. I'm with Karen M on this article -- and learn to put your info on one page -- some of us have neither the time or patience to bother with multi-page articles. I only bothered with this because of the gout issue.

Patricia H.
Patricia H.5 years ago

very useful info

Samir Nassir
Past Member 5 years ago

Thanks for useful info.

Lynn C.
Lynn C5 years ago

Thank you so much for a well-researched and informative article.

Mary L.
Mary L5 years ago

Thanks for the information, I was told that heat was good.

Shalvah Landy
Past Member 5 years ago

Thank you for the information!

Joe R.
Joe R5 years ago