Oxalic Acid and Green Smoothies

By Victoria Boutenko
An overview of scientific research in response to the Article “How Green Smoothies Can Devastate Your Health” by Sarah, The Healthy Home Economist

A Common Misunderstanding                                                                     

Dear Friends, in this article I present lots of citations from original research documents. To make your reading a little easier I have highlighted the keywords.

About 85% of all kidney stones contain calcium salts, calcium oxalate, and/or calcium phosphate. It seems logical to connect calcium oxalate with oxalic acid in some foods, such as spinach, soy, tea, coffee, wheat, and some others. However, you will not find any scientifically documented evidence that oxalic acid in food causes the formation of kidney stones. On the contrary, substantial scientific research in different countries has demonstrated that oxalic acid from food plays an insignificant role in the formation of kidney stones.

For example, according to the Journal of the American Society of Nephrology, in 2007 one of the largest and longest studies (44 combined years) was conducted in Boston. This study prospectively examined the relation between oxalate intake and incidence of kidney stones in humans. In the course of this study, the researchers examined 240,681 people (45,985 men, 92,872 older women, and 101,824 younger women). A total of 4605 incident kidney stones were documented. The conclusions were, “the relation between dietary oxalate and stone risk is unclear. Oxalate intake and spinach were not associated with risk in younger women. These data do not implicate dietary oxalate as a major risk factor for kidney stones.” 1

Here is a conclusion from another large medical research group in North Carolina: “The role of dietary oxalate in calcium oxalate kidney stone formation remains unclear. 2

Excesses in Animal Protein are a Major Risk Factors in Kidney Stones Formation.

Multiple studies in different countries have demonstrated that the overconsumption of animal protein is a major risk factor in kidney stones Formation. I have chosen nine thoroughly documented studies that clearly display the true cause of kidney stones.

According to the research conducted by Leiden University Hospital (The Netherlands,) “dietary excesses in animal protein and/or salt have been implicated as risk factors in calcium oxalate kidney stones formation.”

The results show that high animal protein and/or sodium intake decreases the ability of urines to inhibit the agglomeration of calcium oxalate crystals and provide a possible physicochemical explanation for the adverse effects of dietary aberrations on kidney stone formation. 3

Similar conclusions were made by the Center in Mineral Metabolism and Clinical Research in Dallas, Texas: “The animal protein-rich diet was associated with the highest excretion of undissociated uric acid due to the reduction in urinary pH. The oxalate excretion was lower than during the vegetarian diet. 4

Researchers from the Kaizuka Municipal Hospital in Japan came to the same conclusions. They investigated the daily eating habits of 241 men with a history of kidney stones. They discovered that these patients ingested “much more total protein and animal protein than healthy Japanese. The amount of ingested nutrients during the evening meal by the patients was about 50% of the daily amount with over 60% of the daily animal protein being ingested at dinner.”

After evaluation of gathered data the patients received the following general guidelines: 1) increased fluid intake, 2) correct and avoid unbalanced diet (the diet should include all kinds of food, with vegetables being eaten at every meal and avoidance of an excessive intake of meat), 3) eat three meals a day and avoid an excessive intake at dinner, and 4) extend the interval from dinner until retiring. By following these individual dietary guidelines, the 5-year stone recurrence rate and the stone episode rate decreased remarkably in the period of not only outpatient visits but also in the period when the outpatient visits were discontinued. From these results, scientists concluded that individual dietary management should be the primary measure for the prophylactics of kidney stone disease in Japan. 5 Please note, their four food guidelines do not include any limitation of spinach.

British researchers drew similar conclusions. The hypothesis that the incidence of calcium stone disease is related to the consumption of animal protein has been examined. Within the male population, recurrent stone formers consumed more animal protein than did normal subjects. Single stone formers had animal protein intakes intermediate between those of normal men and those of recurrent stone formers. A high animal protein intake caused a significant increase in the urinary excretion of calcium, oxalate and uric acid, 3 of the 6 main urinary risk factors for calcium stone formation. The overall relative probability of forming stones, calculated from the combination of the 6 main urinary risk factors, was markedly increased by a high animal protein diet. Conversely, a low animal protein intake, such as taken by vegetarians, was associated with a low excretion of calcium, oxalate, and uric acid and a low relative probability of forming stones. 6

In Italy nutrition has been widely recognized to influence the risk of kidney stone formation. Therefore the Italian researchers aimed to assess: a) whether the usual diet of women with idiopathic calcium kidney stones living in Parma (Northern Italy) is different compared to healthy controls, b) how their diet differs from Italian National guidelines and c) whether it is related to kidney stones clinical course.

143 women with recurrent kidney stones and 170 healthy women were enrolled. Stone formers showed higher consumption of sausages, ham, meat, and sweets than healthy controls. The intake of fruit and vegetables was notably lower than guideline recommendations.

Italian scientists concluded that “the usual diet of women with recurrent kidney stones is different from controls and characterized by low intake of fruits and vegetables and higher consumption of simple sugars and foods with high protein and salt content. This dietary imbalance could play a role in the ICN pathogenesis, especially in younger women. This work was financed by grants from the Italian Ministry of University and Research as part of a larger project about the prevention of kidney stones.” 7

Another study from Japan examined the statistical association between the formation of different kidney stones and diet. “Excessive intake of coffee, tea, and alcoholic beverages seemingly increased the risk of renal calculi. Many dietary elements have been suggested by numerous clinical and experimental investigations, but a few elements are substantiated by analytical epidemiological investigations. Increased ingestion of animal protein and sugar and a decreased ingestion of dietary fiber and green-yellow vegetables are linked with the higher probability of stone formation in the industrialized countries”. 8

According to the research at Medizinische Klinik from Wadenswil in Switzerland, “Excess intake of flesh protein (meat, fish, poultry) is lithogenic since it increases urinary calcium, oxalate and uric acid, and lower citrate. On the other hand, a diet rich in alkali (vegetables, fruit) is associated with a lower risk of stone formation. A “common-sense diet” containing sufficient amounts of fluids, 1200 mg of calcium per day, and reduced amounts of flesh protein as well as salt is able to reduce the 5-year stone recurrence rate in calcium stone formers by 50%. 9

Here is a quote from the new research conducted at the University of California School of Medicine: “Managing diet, medication use, and nutrient intake can help prevent the formation of kidney stones. Obesity increases the risk of kidney stones. However, weight loss could undermine the prevention of kidney stones if associated with a high animal protein intake, laxative abuse, rapid loss of lean tissue, or poor hydration. For prevention of calcium oxalate, cystine, and uric acid stones, urine should be alkalinized by eating a diet high in fruits and vegetables, taking supplemental or prescription citrate, or drinking alkaline mineral waters. 10

The Study Showed no Association between Oxalate Intake and Vulvodynia

The School of Public Health at the University of Minnesota recently conducted a large study about the association between oxalate Intake and vulvodynia. The research involved 242 women with, and 242 women without vulvodynia from nine ethnically diverse Boston-area communities. There was “no increase in the risk of developing vulvodynia with increasing of estimated oxalate intake. In addition, we saw no association between increased consumption of various food items high in oxalate content and the risk of vulvodynia.”

Researchers’ conclusion: “dietary oxalate consumption does not appear to be associated with an elevated risk of vulvodynia.” 11

 Successful Treatment of Kidney Stones with Chlorophyll

As you may remember from chemistry, magnesium is a major mineral in chlorophyll. Almost a century ago, in 1929, renowned Swedish researcher Greta Hammarsten 12 described in her science papers that a deficiency of magnesium led to an increase in the urinary excretion of oxalate in humans, the process is reversed when magnesium was supplied.

After decades of research, she concluded that “A reduction of the magnesium or calcium content, or both, in the diet, will bring about the formation of [kidney stones]. If, in addition, the content of vitamins A and D is very low, the frequency of the [kidney stones] increases, and the stones will be considerably larger in size. Further, an acidotic diet leads to an increased calcium excretion in the urine, resulting in a greater risk of the formation of [kidney stones].

I find the words of this woman to be amazingly prophetic: “A so-called “synthetic” diet might be thought to be lacking in certain necessary, but as yet unknown, substances present in milk and green leaves.” 13

76 years later, in 2005, Linda Massey, a researcher from Washington State University in Spokane, confirms: “Magnesium (Mg) acts as a competitor to calcium in oxalate binding. However, magnesium oxalate (MgOx) is more soluble than calcium oxalate (CaOx), 0.07 g/100 mL versus 0.0007 g/100 mL respectively, so MgOx does not form stones at physiological urine concentrations.”

Massey’s research demonstrates that magnesium deficiency causes the stone formation and both theoretical considerations and animal studies support trials of magnesium supplements as therapy for [kidney stones].

According to clinical studies in Germany, “Dietary magnesium is unlikely to be deficient if the diet includes green leafy vegetables and whole grains, as magnesium is a major mineral in chlorophyll. 14

Dr. Eric Taylor of Portland, ME, followed 45,619 men for 14 years, with dietary assessments every four years. His team of researchers presented the evidence of the effectiveness of increased magnesium in preventing symptomatic kidney stones. 15

In Germany, medical researchers “have been successfully inhibiting crystallization of calcium oxalate in rabbits by treating them with chlorophyll.” 16

 Health Benefits in Oxalic Acid

The earliest mention of oxalic acid as a benefit for human health probably belongs to Doctor Norman Walker. In his book “Fresh Vegetable and Fruit Juices” he states: “Raw oxalic acid is one of the important elements needed to maintain the tone of, and to stimulate peristalsis.”

In the book “Oxalic Acid in Biology and Medicine” Albert Hodgkinson stated that: “A mean value of 288mcg of anhydrous oxalic acid/100ml was reported for normal human blood” 17

In Turkey, scientists discovered that in animals oxalate can promote a rapid increase in white blood cells: “Recent studies indicate that the levels of oxalate are too high for the substance to only be an end-product of the metabolism in animals. Therefore, it has been suggested that there could be an oxalate oxidase pathway in animals, which uses oxalate to produce hydrogen peroxide (H2O2), which could then be used to promote a “burst” of phagocytes, white blood cells that engulf and break down foreign particles, cell debris, and disease-producing micro-organisms. 18

Dr. Supriya Yadav from the Agharkar Research Institute, India, reported that “oxalic acid when combined with zinc sulfate and other salts was able to significantly inhibit the growth of E.coli.” 19

Colonel Joe Hart of Arkansas has been granted three patents for the application of oxalic acid for the treatment of cancer, bacterial and viral infections, and vascular diseases. You may read the text of his patent online: http://www.patentstorm.us/patents/6133317.html. Joe Hart’s website is: http://www.coljoe.com

Jennifer Prescott 20 after her own investigation concluded that oxalic acid is the cure for cancer: “Research reveals there is one common denominator in the foods known as great antioxidants. They are all high in oxalic acid.”

“Oxalic acid is needed by our body for many functions and plays an important role in colon health, so much so that when it is not received through the diet, the body synthesizes it from ascorbic acid.” 21

I would like to add my own observations. Since I published my first book about green smoothies, “Green for Life” in 2005, I have been receiving an ever-growing avalanche of emails with healing stories. I have written several more books and e-books with more guidance on green smoothies, such as the importance of rotating your greens in daily recipes, how much to use, when, and how often to consume green smoothies and many more. “Green for Life” has been translated into more than 40 languages.

When people try green smoothies and observe how they feel, they witness for themselves the solid evidence of the healing power of greens and green smoothies. You may view dozens of recorded testimonials online (here) and read many more healing stories on our blog. (here) Adding green smoothies to your diet is not a

fad, but rather a step in the direction of natural living.


Recipes of Green Smoothies with Little Oxalic Acid.

For those of you, who would rather not consume high amount of oxalic acid, I have put together nine recipes of green smoothies with very low oxalic acid content.

Sweet Sprouts

1 bunch green leaf lettuce

1 handful alfalfa sprouts

2 ripe apples, peeled, pits and stems removed

2 ripe bananas, peeled

2-3 cups water

Blend well.

Yields 2 quarts

Romaine Green Empire

1 head romaine lettuce

2 ripe apples, peeled, pits and stems removed

1 ripe mango, peeled, pit removed

3 cups water

Blend well.

Yields 2 quarts

Green Freshness

1 head red leaf lettuce

1 ripe cantaloupe, peeled, seeds removed

1 cup fresh apple juice

2 cups water

Blend well.

Yields 2 quarts

Nectarine Grape Smoothie

1 head oak leaf lettuce

4 ripe nectarines, pits removed

1 cup green grapes

2 cups water

Blend well.

Yields 2 quarts

Lettuce Drink to Your Health

1 handful red leaf lettuce

1 handful green leaf lettuce

1 cup bing cherries, pits removed

2 ripe bananas, peeled

2 cups water

Blend well.

Yields 2 quarts

Simple and Tasty

1 head butterhead lettuce

1 ripe honeydew, peeled, seeds removed

2 cups water

Blend well.

Yields 2 quarts

Green Dream Pudding

1 head iceberg lettuce

1 ripe Mexican papaya, peeled, seeds removed

½ lemon (juice only)

½ cup raisins

1 cup water

Blend well. Use tamper, if needed.

Yields 1 quart

Spicy Creamy Soup

1 cup mustard greens

1 medium avocado, pit removed

1 red bell pepper, seeds removed

1 lemon, juice only

2 cups water

Blend well.

Serve with alfalfa sprouts

Yields 1 quart

Dill Soup

1/2 head romaine lettuce

1 medium avocado, pit removed

1 cucumber, peeled

1 sprig fresh dill

2 cups water

Blend well.

Serve with alfalfa sprouts

Yields 1 quart

[1] E. Taylor, G. Curhan, “Oxalate Intake and the Risk for Nephrolithiasis.” The Journal of the American Society of Nephrology, Jul. 2007, Channing Laboratory, Brigham and Women’s Hospital, Boston, MA USA.

[2] R. Holmes, D. Assimos, “The Impact of Dietary Oxalate on Kidney Stone Formation.” Urological Research, Oct. 2004, Department of Urology, Wake Forest University Medical School, Winston-Salem, NC, USA.

[3] Dirk J Kok et al, “The Effects of Dietary Excesses in Animal Protein and in Sodium on the Composition and the Crystallization Kinetics of Calcium Oxalate Monohydrate in Urines of Healthy Men.” The Journal of Clinical Endocrinology and Metabolism, Oct. 1990, Department of Endocrinology, University Hospital, Leiden, The Netherlands.

[4] Neil A Breslau et al, “Relationship of Animal Protein-Rich Diet to Kidney Stone Formation and Calcium Metabolism.” The Journal of Clinical Endocrinology and Metabolism, Jan 1988, Center in Mineral Metabolism and Clinical Research, Department of Internal Medicine, Dallas, Texas, USA.

[5] M. Iguchi, T. Umekawa et al ,”Dietary Habits of Japanese Renal Stone Formers and Clinical Effects of Prophylactic Dietary Treatment.” Hinuokika Kiyo. Acta Urologica Japonica, Dec. 1989, Department of Urology, Kaizuka Municipal Hospital, Japan

[6] W. Robertson et al, “Should Recurrent Calcium Oxalate Stone Formers Become Vegetarians?” British Journal of Urology, Dec. 1979

[7] T. Meschi et al, “Dietary Habits in Women with Recurrent Idiopathic Calcium Nephrolithiasis.” Journal of Translational Medicine, Department of Clinical Sciences, University of Parma, Parma, Italy.

[8] H. Kodama, Y. Ohno, “Analytical Epidemiology of Urolithiasis”, Hinuokika Kiyo. Acta Urologica Japonica, Jun. 1989, Department of Public Health, Nagoya City University Medical School, Japan.

[9] B. Hess, “Pathophysiology, Diagnosis and Conservative Therapy in Calcium Kidney Calculi”. Therapeutische Umschau. Revue Therapeutique, Feb. 2003, Medizinische Klinik, Spital Zimmerberg, Wädenswil, Switzerland.

[10] L. Frassetto, I. Kohlstadt, “Treatment and Prevention of Kidney Stones: an Update.” American Family Physician, Dec. 2011, University of California School of Medicine, San Francisco, CA, USA.

[11] Bernard Harlow et al, “Influence of Dietary Oxalates on the Risk of Adult-Onset Vulvodynia.” Division of Epidemiology and Community Health, School of Public Health, Mar. 2008, University of Minnesota, Minneapolis, USA, harlow@epi.umn.edu

[12] Hammarsten G. On calcium oxalate and its solubility in the presence of inorganic salts with special reference to occurrence of crystaluria. C R Trav Lab Carlsberg 1929

[13] Greta Hammarsten, “Dietetic Therapy in the Formation
of Calcium Oxalate Calculi in the Urinary Passages.” From the Medico-Chemical Institute, Lund, Sweden, June 1938.

[14] Linda Massey, “Magnesium Therapy for Nephrolithiasis” Magnesium Research, Jun. 2005, Food Science and Human Nutrition, Washington State University, Spokane, WA, USA

[15] Eric Taylor, et al, “Dietary factors and the risk of incident kidney stones in men: New insights after 14 years of follow-up.” The Journal of the American Society of Nephrology, 2004

[16] W. Berg, C. Bothor, H. Schneider, “Experimental and clinical studies concerning the influence of natural substances on the crystallization of calcium oxalate.” Der Urologe, Jan. 1982, Germany

[17] Albert Hodgkinson, Oxalic Acid in Biology and Medicine, Academic Press, London, New York,1977

[18] Mahmut Caliskan, “The Metabolism of Oxalic Acid,” Mustafa Kemal University, Nov. 1998. Department of Biology, Hatay, Turkey.

[19] Nathan Gray, “Probiotic Effect May Benefit from Micronutrient Boost, Suggests Study.” Jan. 2011, http://www.nutraingredients-usa.com/Research/Probiotic-effect-may-benefit-from-micronutrient-boost-suggests-study?utm_source=copyright&utm_medium=OnSite&utm_campaign=copyright

[20] “Oxalic Acid – The Cure For Cancer”, Jan. 2008, http://EzineArticles.com/912295

[21] “In Defence of Oxalic Acid”, http://www.dewsworld.com/FInDefenseofOxalicAcid.html