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.
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, death from cardiovascular collapse, on the respiratory system, throat – 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.
For Clarity: How toxic is Oxalic Acid?
“From an MSDS (Material Safety Data Sheet) for Oxalic acid, LD50 (LD50 is the Median Lethal Dose, which is the dose of a drug or chemical predicted to produce a lethal effect in 50 percent of the subjects to whom the dose is given) in rats is 375 mg/kg. So for a person about 145 pounds (65.7 kg) that’s about 25 grams of pure oxalic acid required to cause death. Rhubarb leaves are probably around 0.5% oxalic acid, so that you would need to eat quite a large serving of leaves, like 5 kg (11 lbs), to get that 24 grams of oxalic acid. Note that it will only require a fraction of that to cause sickness.” - The Rhubarb Compendium
Is This Possible? The Murky Middle
- Oxalic acid is a naturally occurring substance in plants, animals, and in humans.
- I often think that anything with the word acid in it will scare people but not all acid are bad. Remember that Omega 3 which everyone is 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!
- Foods that contain significant amounts of oxalic acid are ( in order from highest to lowest): buckwheat, star fruit, black pepper, parsley, poppy seed, rhubarb stalks, amaranth, spinach, chard, beets, cocoa, chocolate, most nuts, most berries, and beans. If you had to really avoid oxalic acid that would be difficult.
- There is a thought 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 black tea due to its high oxalate content increases kidney stone formation but recent research has shown it to have a preventive effect.
2. Victoria Boutenko of the Raw Food Family sites 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 actually animal protein.
3. Oxalic acid 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 the enough oxalic acid in our blood because this eliminates all 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.
- 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 will decompose oxalic acid in the blood. This usually weakens the immune system so the body is unable to fight off viral or bacterial disease. Is this why many cancer patients die from cancer related to viral pneumonia.
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, star fruit, 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 and nuts and buckwheat and cabbage…… totally eliminate junk food… and fast food, and packaged food and micro-waved food and 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.
Below are a few powerfoods HIGH in oxalic acid. You can read their many benefits.
Dandelion Greens: I love to add this in the summer.
Spinach is the First Green Powerfood How could Popeye be wrong?
About Diana Herrington
I am the Founder and Author at Real Food For Life. Have been teaching cooking classes worldwide since 1982. Create original, healthy recipes and menus, which are gluten free and white sugar free. Also, the author of the GREEN means LEAN and Balance Your Body e-books. I turned a debilitating health crisis into a passion for helping others with healthy, sugar free, gluten free eating and cooking.
Tags: oxalic acid