Know your greens and be cautious about using too many in smoothies

Know your greens and be cautious about using too many in smoothies

 With the Raw Food Revolution well under way and people talking about “Green Smoothies” and eating more salad, it has become apparent that we should know our plant foods a little more intimately. More is not always best, especially in a society that often forgets about moderation. In this article I am going to explore a component of many greens (and other foods) called oxalic acid.


I will look at what it does to the body in large quantities and how to keep its consumption in balance. I will also address the other side of the story because when it comes to natural health and nutrition, there is ALWAYS another side. The purpose of this article is not to scare people away from plant foods as they are such an important part of our daily diet. The purpose is to explore how this substance reacts with the body and the importance of knowing which foods to eat in abundance and which to eat in moderation.What is oxalic acid

According to the English Dictionary, oxalic acid is “a colourless poisonous crystalline dicarboxylic acid found in many plants: used as a bleach and a cleansing agent for metals”.  This substance is naturally occurring in some plants including sorrel, rhubarb, cocoa beans, parsley, spinach and beer. For a full list, see below. Oxalic acid is often known as an “anti-nutrient” due to the way it creates salts known as oxalates when it binds with certain minerals like calcium and magnesium. Most researchers claim that these salts have no positive use by the body and are excreted through the urine. It is important to note however, that our bodies also create oxalic acid naturally and external consumption only accounts for 10-15% in most people. Some researchers have suggested that oxalic acid plays some as-yet-little-understood beneficial roles in the immune system and toxin scavenging in the body.[1] It wouldn’t be the first time the full story is not yet known!

Foods with Higher Levels of Oxalic Acid
I say “higher levels” rather than “high levels” because the levels are not actually that high in relation to the many other constituents of each plant. For a number of reasons, it is difficult to give exact quantities of oxalic acid in each plant. This is because different factors vary the outcome. For example, the amount of oxalic acid in a plant will depend on the environment in which the plant was grown. Furthermore, the amount of acid present maybe different to the amount actually absorbed into the body. The way a food is prepared will also influence the quantities as well as when that plant was picked. If you research various lists citing percentages of the acid in different plants, you will find that there are rarely consistencies despite the fact that the creators of those lists are credible. Below is a list of plants that do contain measurable amounts of the substance:

dried figs
purple grapes
citrus peel
kiwi fruit

beans (green, wax, dried)
beets (tops, roots, greens)
mustard greens
peppers, green
summer squash
sweet potatoes
Swiss chard
Bread, whole wheat
Stone ground flour Buckwheat Wheat bran Oatmeal Wheat germ Pop corn Whole wheat flour Spelt Amaranth
sesame seeds sunflower seeds
cocoa beans

The effect of too much Oxalic Acid
Most sources agree that there are two situations in which a person will be affected by oxalic acid. The first is one I mentioned previously where foods high in the substance are consumed in out of balance quantities. The amount of oxalic acid, even in plant foods high on the list, is quite easy for the body to dispose of and the average person need not give their consumption a second thought. On the other hand if you were to throw common sense away and eat only plant foods high in oxalic acid, you may run into trouble. The key is to keep the bigger picture in perspective.  Many of these plants have so many nutritional benefits that it would be silly to eliminate or even greatly reduce them in your diet if you are a healthy individual who eats a variety of foods in moderation. Numerous studies have shown that a varied diet containing plants high in oxalic acid produces no negative effect.

The second group of people who could be in danger from oxalic acid are those suffering with kidney stones or other kidney problems, gout, rheumatoid arthritis or various forms of vulvar pain. The oxalates formed by the combining of oxalic acid and various minerals in the body actually form crystals, which irritate the kidneys and can form kidney stones. These crystals may also irritate the lining of the gut. Taking calcium with foods high in oxalic acid has been shown to reduce oxalate production by up to 97%

The Other Side of the Story
Colonel Joe Hart, claims to have discovered the benefits of oxalic acid in 1992 and actually acquired three patents for the application of oxalic acid for treatment of cancer, bacterial and viral infections, and vascular diseases.

The colonel identified oxalic acid as the substance that would kill cancer cells without harming normal cells. He then identified which foods and environmental factors inhibited the therapeutic value of oxalic acid. Research alternative cancer treatments and you will find the work of Colonel Joe. He is not the only one who has found benefit in this so-called toxin. 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.

Many raw food enthusiasts claim that when the plant food is raw, whether whole or in the form of juice, the oxalic acid is ORGANIC and as such is not only beneficial but essential for the physiological functions of the body. I could not find scientific data to back this up, however if you take a look at most raw foodists, they glow with health.

The NIH (National Institues of Health) states, “For people who eat a variety of foods, these interactions probably have little or no nutritional consequence and, furthermore, are accounted for in the overall calcium DRIs [Dietary Reference Intakes], which take absorption into account.”
According to the book “Fresh Vegetable and Fruit Juices” by Dr. Walker (1936 )

 In Conclusion…
I think that the lesson here is that even when eating natural plant foods, balance needs to be maintained. Just because you hear that something is good for you doesn’t mean you need to consume it at every meal and completely flood your body with it’s newfound benefits.  Traditionally, people ate what was in season and so their diet varied naturally. Your body needs such a wide range and variety of vitamins, minerals, amino acids, omega oils and phytonutrients. You will feed it best through a varied diet of whole foods.

1 Mahmut Çalişkan, “The Metabolism of Oxalic Acid,” Journal of Zoology 24 (2000): 103–106. (very well researched article)

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Green Smoothie

By February 15, 2013

The basics of a green smoothie


Place all ingredients into a blender or food processor and whizz until smooth.

Serve chilled.


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