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Do Plant Based Diets Cause Kidney Stones?

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Do Plant Based Diets Cause Kidney Stones?

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No- They can actually make them go away.
Nutritional Science debunked this idea of high oxalate plant foods causing kidney stones many years ago.

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DANGER OF VEGAN DIET - OXALATES & KIDNEY STONES? Dr. Michael Greger

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Can you go on a vegan diet if you have kidney stones or are at risk of getting kidney stones? What about all the vegetables that contain oxalates? Will eating high oxalate vegetables give me kidney stones? Should avoid all oxalate contain foods if I have kidney stones?

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Are extremely high in oxalates

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Chaga mushroom-induced oxalate nephropathy. - PubMed - NCBI

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What are oxalates? Should I be concerned about oxalates in my diet?

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What are oxalates? Should I be concerned about oxalates in my diet?

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They say ignorance is bliss. Unfortunately, this isn't the case when trying to assemble the puzzle of healing. While the GAPS diet has drastically improved my autoimmune disease, I know there are still missing pieces in my healing journey. Stomach acid was one. Oxalates are another.

Like phytic acid and enzyme inhibitors, plants produce oxalates because they don't want to be eaten! While these molecules can cause health issues for humans, it actually tears up the teeth of insects which try to eat high oxalate foods.

In a non-leaky human gut, oxalates are degraded by the bacteria oxalobacter formingenes. This prevents the molecules from traveling to the large intestine and being absorbed by body tissues. This person would have low oxalate content in blood and urine samples.

In a leaky gut or when oxalobacter is diminished (by antibiotics, for example), oxalates escape into the bloodstream, damaged body tissues, glands, secretory organs and the brain. Out of place, oxalates impair enzymes, oxidize cell membranes, interferes with nutrient absorption, and can even alter DNA transcription. When oxalates link up with calcium, it forms irritating crystals (kidney stones, for example).

But does a leaky gut really make a difference with oxalate build-up? Yes:

Ordinarily, the gut won't absorb much of the oxalate from the diet because most of [it] will be metabolized by flora or just leave the body with the stool. Under other conditions, such as when there is gut inflammation, a lot of dietary oxalate is absorbed. The difference can be as great as going from 1-2% of the dietary oxalate absorbed to 50%. ( Source).

Wow! 1-2% to 50%... that is a huge difference.

Do I need to be concerned about oxalates?

Generally, if you are healthy and have a well-functioning digestive system, you can probably focus on eating a variety of nourishing foods and not worry about oxalates. But you may wish to consider reducing oxalates if you:

have taken antibiotics frequently or for long periods of time

have a leaky gut and food sensitivities/allergies

have any autoimmune issue

have any inflammatory issue like asthma, arthritis or fibromyalgia

have fat maldigestion

are on the autism spectrum or have a brain disorder like A.D.D., depression or dyslexia (Source)

From my research, I've discovered that many folks find a low-oxalate diet quickly makes a noticeable difference with autism and arthritis.

High oxalates on a grain free diet

So why am I calling oxalates a grain-free diet trap? When transitioning from meals filled with convenient starches, many folks to into cardiac arrest on their first day of grain-free and scream, "Just give me something bready!!" (*ahem* I may or may not have shared that experience). Then they discover the solution: almond flour and other ground nuts.

Almonds (and most other nut and seeds) are very high in oxalates. To make things worse, we can consume huge amounts of almonds/nuts/seeds when they are ground into flour and baked into a treat. As a matter of fact, a cup of almond flour contains 90 almonds! The same point applies to nut butters (a tablespoon of almond butter contains 6 almonds).

A high-oxalate diet is not inherently bad. However, it is something to be aware of it you are still struggling with digestive symptoms after transitioning to a grain free diet. I recommend following the Autoimmune Paleo Protocol, a temporary healing diet to seal a leaky gut, before trying a low oxalate diet. So many individuals experience radical shifts in digestion and symptoms after starting the Autoimmune Paleo Protocol.

With that said, here are some popular foods to keep on your oxalate radar:

Common Foods with Medium Oxalates

Fruits: bananas, mandarin oranges, pears, papaya

Vegetables: red potatoes, raw broccoli, boiled carrots, raw collard greens, eggplant, leeks, lima beans, string beans, tomatoes

Grains/Legumes: Lentils, rice, oats, chickpeas

Other: Pumpkin seeds

Common Foods with High/Very High Oxalates

Fruit: berries, persimmons, orange zest (marmalade), lemon zest, lime zest, figs, currants, dates

Vegetables: raw and steamed carrots, potatoes, sweet potatoes, celery, beets, chard, cooked broccoli, cooked brussels sprouts, cooked cabbage, chili peppers, rhubarb, spinach, peppers, processed tomatoes (canned, sauce or paste)

Grains/Legumes: Most grains and starches (wheat, rye, kamut, buckwheat, millet, sorghum, arrowroot, potato starch, rice flour). Also most beans (black beans, chickpeas, navy beans). All soy products, too (but you are generally avoiding those already... right?) .

Other: Most nuts and seeds, including nut/seed butters and flours (almonds, macadamias, cashews, pecans, pine nuts, walnuts, sesame seeds, hazelnuts, flax seeds, sunflower seeds, pistachios). Also: stevia, chocolate, carob, kombucha and chia seeds

(Adapted partly from this chart. You can find a more detailed list there.)

UPDATE: Many readers have told me that the most accurate and up-to-date information about the oxalate content in certain foods can be found by joining the Yahoo Trying Low Oxalates Group.

"OMG... I'm gonna starve!"

You're probably asking me, " Is nothing sacred? Now even organic spinach is cursed! " Take a deep breath... we're going to get through this!

First: if you suspect that your symptoms may improve by reducing oxalates, it is not all-or-nothing. Let grassfed/pastured/local meats, eggs, dairy (like my homemade raw yogurt), and low oxalate produce make up the bulk of your meals. Then mindfully include small amounts of medium oxalate treats on occasion. Remember, a grain-free diet like the GAPS diet can reverse a leaky gut. So look forward to a high oxalate indulgence in the future, after some healing has taken place.

If you don't want to go on a full-blown low oxalate diet, be mindful of the high oxalate foods you are currently eating. Are your desserts made of dates and ground nuts? Do you have a green smoothie everyday? Those are places where you can make an easy change. Simply leave the spinach out of your smoothie and use raw honey instead of dates.

Also, gradually reduce oxalate consumption to prevent an overwhelming detox reaction. In a Julie Matthew's interview, the autism/nutrition expert's guest explained:

Calculate, as best as you can, how high‐oxalate your diet is beforehand, if it's very high, reduce one item at a time, if you're using almond flour, don't pull almond flour completely outright, but maybe substitute a lower oxalate flour like chestnut, it's also high oxalate but it's nowhere as high as almond and just start slowly reducing. The one thing that you don't want to do is detox faster than your body can handle. ( Source)

Also, coconut flour is low oxalate so you can enjoy the recipes on my Recipe page and in my Indulge and Heal ecookbook!

If you consider yourself healthy with a wonderfully competent intestinal lining (I'm jealous), then you have room to relax about oxalates. Enjoy some kombucha, tamari sauce and almond butter. Just remember the cardinal rule: moderation.
Are you trying to juggle a low oxalate diet and a grain-free diet? Have you found a low oxalate lifestyle helpful in ameliorating health issues?

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What are oxalates? Should I be concerned about oxalates in my diet?

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They say ignorance is bliss. Unfortunately, this isn't the case when trying to assemble the puzzle of healing. While the GAPS diet has drastically improved my autoimmune disease, I know there are still missing pieces in my healing journey. Stomach acid was one. Oxalates are another. What are Oxalates?

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How to Treat Kidney Stones with Diet - YouTube

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How to Treat Kidney Stones with Diet - YouTube

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Subscribe to Dr. Greger's free nutrition newsletter at http://www.nutritionfacts.org/subscribe and get a free excerpt from his latest NYT Bestseller HOW NOT TO DIE. (All proceeds Dr. Greger receives from his books, DVDs, and speaking go to charity). DESCRIPTION: Decreasing animal protein and sodium intake appears more effective in treating calcium oxalate and uric acid kidney stones (nephrolithiasis) than restricting calcium or oxalates.

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Smarter Science of Slim, SANE Solution | Can All Those Non-Starchy Vegetables Give Me Kidney Stones?

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Smarter Science of Slim, SANE Solution | Can All Those Non-Starchy Vegetables Give Me Kidney Stones?

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Catherine Britell, M.D.
We love our non-starchy vegetables! And for most of us, eating ten or more servings of non-starchy vegetables (concentrating on the dark green ones) per day is the mainstay of a healthy diet. If you have had kidney stones, however, you'll need to pay attention to the contained in the vegetables you eat. The good news: this is not difficult, and armed with the right information you can still enjoy plenty of low-oxalate non-starchy vegetables.

People who are overweight or obese need to be aware of the possibility of kidney stones. Compared with persons at or near ideal body weight (BMI = 21-23), obese men (BMI ≥30) have a 33% greater risk for kidney stone formation, while obese women have a 200% greater risk. ( Taylor EN, Stampfer MJ, Curhan GC. Obesity, weight gain, and the risk of kidney stones. JAMA. 2005;293:455-462)

We know that 75% of kidney stones are calcium oxalate stones, and oxalates in the diet can be important causative factors. So, for someone who has had one or more calcium oxalate kidney stones, the general recommendation is limiting oxalates to 50-60 mg/day. For these people, getting 8-10 servings of non-starchy vegetables can present a bit of a challenge. Spinach, chard, beet greens, and many others of those beautiful dark-green non-starchy veggies have large concentrations of oxalates. Also strawberries and most nuts need to be limited or avoided if you must limit oxalates.

However, there are many low-oxalate vegetables - asparagus, broccoli, cauliflower, cucumbers, iceberg and Romaine lettuce, radishes, mushrooms, onions (yellow and white);,squash (zucchini, acorn, and yellow), red sweet peppers, turnips (root), water chestnuts and bok choi - that we can eat in quantity and still keep our diet low in oxalate.

Here are some oxalate levels in a few common non-starchy and non-sweet fruits and veggies:

Beet greens, cooked 1/2 cup - 916

Rhubarb, stewed, no sugar 1/2 cup - 860

Spinach, cooked 1/2 cup - 750

Beets, cooked 1/2 cup - 675

Chard, Swiss, leaves cooked 1/2 cup - 660

Rhubarb, canned 1/2 cup - 600

Spinach, frozen 1/2 cup - 600

Beets, pickled 1/2 cup - 500

Endive, raw 20 long leaves - 273

Cocoa, dry 1/3 cup - 254

Dandelion greens, cooked 1/2 cup - 246

Okra, cooked 8-9 pods - 146

Kale, cooked 1/2 cup - 125

Peanuts, raw 1/3 cup (1-3/4 oz.) - 113

Turnip greens, cooked 1/2 cup - 110

Chocolate, unsweetened 1 ounce - 91

Parsnips, diced, cooked 1/2 cup - 81

Walnuts, 100grams - 77

Collard greens, cooked 1/2 cup - 74

Pecans, halves, raw 1/3 cup (1-1/4 oz) - 74

Black Tea, leaves (4 mm. infusion) 1 level tsp in 7 oz water - 72

Carrots, cooked 1/2 cup - 45

Brussels sprouts, cooked 6-8 medium - 37

Strawberries, raw 1/2 cup - 35

Celery, raw 2 stalks - 34

Raspberries, black, raw 1/2 cup - 33

Orange, edible portion 1 medium - 24

Green beans, cooked 1/2 cup - 23

Chives, raw, chopped 1 tablespoon - 19

Leeks, raw 1/2 medium - 15

Blackberries, raw 1/2 cup - 13

Blueberries, raw 1/2 cup - 11

Raspberries, red, raw 1/2 cup - 10

Broccoli, cooked 1 large stalk - 6

Asparagus, 1/2 cup - 5.2

Tomatoes 1 medium raw - 2.0

Bok choy 1 cup 1.6 - mg

Cauliflower 1/2 cup - 1.0

There are many places on the Web to find out the oxalate content of various veggies and fruits.

The Bottom Line: People who are prone to kidney stones can build a healthy diet around low-oxalate veggies. (i.e., broccoli is your friend!) Another important dietary consideration for those who develop kidney stones is the need for adequate calcium. (800-1200 mg/day) The Greek yogurt that I love has 200 mg of calcium per serving. Again, broccoili is our buddy here, with almost as much: 180 mg/serving. And Bok Choy with a whopping 180 mg/cup. Celery is also calcium-rich.

And here's another sweet morsel: Green tea can be beneficial in this regard! It seems that green tea binds to calcium oxalate, creating crystals that break down easily so that they pass out through the urine unnoticed while they are tiny. So, if you have had kidney stones, enjoy your low-oxalate non-starchy vegetables and perhaps a few cups of brewed green tea every day!

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Can All Those Non-Starchy Vegetables Give Me Kidney Stones?

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Catherine Britell, M.D. We love our non-starchy vegetables! And for most of us, eating ten or more servings of non-starchy vegetables (concentrating on the dark green ones) per day is the mainstay of a healthy diet. If you have had kidney stones, however, you'll need to pay attention to the contained in the vegetables you eat.

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Kefir is, by definition, a fermented beverage made from milk. Similar in nature to yogurt, this decadent drink is packed with beneficial bacteria, or probiotics. Kefir usually has a creamy texture and a light foam with a little bit of natural carbonation. The lactobacillus bacteria ferments, creates lactic acid, and gives the kefir its trademark tang.
Why Choose Kefir?
Kefir has a number of health benefits. It differs from yogurt, which is also fermented dairy, because of the type of bacteria used. Both use forms of lactobacillus, but kefir usually contains anywhere from 7 to 10 different cultures, most of which are derived from "kefir grains". While yogurt can vary in texture, kefir is always found in liquid form. Kefir is generally believed to be much higher in probiotic content than yogurt alone. You can still of course take probiotic supplements if you are using Kefir, it's best if you look at this article titled How To Choose A Good Probiotic as well as the Probiotics101 website to get more details.

Some of the health benefits include:

The stimulation of digestion;

Cholesterol reduction;

Improvement of enzyme production in the stomach and pancreas;

Improvement of lactose digestion;

The promotion of weight loss (with 2-3 servings of dairy per day);

Increased immunity and adjustment to hormonal changes in pregnant women.

Believe it or not, kefir has also been used to make body cleansers, facial masks, hand creams, and even hair products. Alpha Hydroxy Acid (AHA), also found fruits, can be found in kefir as well. It exists in kefir as lactic acid and can help rid the body of dead skin cells.
Producing Your Own Vegan Alternative
While organizations like the National Kefir Association claim there is no non-dairy alternative to kefir, those who are on vegan or lactose-free diets are obviously going to seek to create alternatives so that they can benefit from the high levels of probiotic cultures. Despite the group's officially stated viewpoint, there are several kefir recipes that focus on water, coconut water, and other base ingredients.

Variations on kefir can vary, depending on your favorite base ingredients. A lot of people make kefir with plain water while others like to use nut milks or even coconut water or milk. If you want to make a super-pure kefir, make your own nut milk (like almond milk) and then use that to make your kefir.

It is important to note that the kefir grains used in making milk keifer and water-based keifers are different because of the way the dairy interacts. You'll want to make sure you are buying water keifer grains to use as your starter culture. You can convert milk kefir grains to water kefir. The process for making a simple water kefir is pretty easy:

Gather your ingredients. You'll need about 1 cup of water and 1 TBSP of sugar per tablespoon of kefir grain you use. Make sure you use water that is as pure as possible. Water that is low in chlorine and high in minerals is best.

To flavor your kefir, you'll want to choose a dried fruit. Look for fruits that are high in flavor and minerals, but without sulphur. You only need a handful. Try raisins, figs, peaches, pomegranate, cherries, candied ginger, and unsulphured apricots.

Rehydrate your grains if you purchased them dried. If you purchased them otherwise, rinse them off and get rid of any excess liquid. Some recipes say you can place the dried grains in your jar and use them that way. If you do so, your fermentation process will take longer.

Add your sugar and kefir grains to your jar (remember 1TBSP sugar to 1TBSP grain). The sugar will "feed" the grain, allowing it to grow and ferment. This is the point where you'd add your dried fruit as well.

Add your water to the jar, leaving some space at the top. The water should be cool or room temperature. Stir until the sugar you've chosen has dissolved.

Cover your jar with a breathable fiber, like a coffee filter or piece of cheesecloth. You want the air to be able to get in while keeping flies and bugs out. Place the jar in a place with a stable temperature for about 24-48 hours.

Your kefir, when tasted, should be slightly sweet and tangy. If it's too sweet, it's not done yet. If it's sour, it's overdone.

When the taste is right, strain the kefir into a bowl to get rid of the scum, floating grains, and fruit.

Place your finished kefir in a clean jar. You can drink it right away or put it in the fridge. If you store it, make sure you leave enough space at the top of the jar to account for carbonation buildup so your jar doesn't explode. This is the point where you can really add some extra flavoring, if you choose.

Take the grains you strained and put them back into your original jar to start your recipe over again right away, if you choose.

Take note - it's important to use glass jars when making and storing kefir. Kefir can be acidic and will cause plastic to leech. Non-reactive metal containers - like stainless steel - can sometimes be used, but it's safer, in general to avoid metals and use glass.

Kefir is incredibly easy to make and the process is one you can repeat over and over again. Once you have the hang of it with water, you can try it with coconut milk, coconut water, almond milk, and other base liquids. The choice is up to you!

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Exploring Kefir - Vegan Alternatives to Fermented Dairy

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Kefir is, by definition, a fermented beverage made from milk. Similar in nature to yogurt, this decadent drink is packed with beneficial bacteria, or probiotics. Kefir usually has a creamy texture and a light foam with a little bit of natural carbonation. The lactobacillus bacteria ferments, creates lactic acid, and gives the kefir its trademark tang.

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After quickly reading these informational articles  here are a couple things that might help no matter how you metabolize oxalates or what type of diet you prefer.

1. Be aware of and moderate the amount of oxalate rich foods you eat if you are sensitive to oxalates.

2. Eat More Avocado- They help you absorb more from the plant foods you eat and promotes good gut bacteria that can help reduce oxalate absorption.

3. Eat Good Belly, Kefir, and other probiotics that promote Lactobacillales.

4. Eat more squash, broccoli, & raisins, they are naturally have low oxalate levels.  Here is a link to a great broccoli raisin salad with cashews-

http://www.canyoustayfordinner.com/2011/10/05/broccoli-salad-with-cashews-and-raisins/  Kari and I  take it along with a fruit salad to pot luck events.

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Taurine Important for making bile acid taurocholate which limits absorption of oxalate. Take if stool turns yellow.

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by Jack Norris, RD * Last updated December 2013

Contents

Summary

Oxalate is a molecule many in the vegan community are familiar with for preventing the absorption of calcium. This article does not address that subject-info can be found in the section Calcium Absorption from Plant Foods.

Oxalate is also known for the part it plays in calcium-oxalate kidney stones, which is the most common form of kidney stone.

In many cases, getting a kidney stone is a one-time thing and does not occur again. Increasing fluid intake can cut the incidence of getting another stone in half. Cutting down on the amount of oxalate in the diet is another strategy for reducing stone recurrence. Some calcium-oxalate stone formers are prescribed potassium-citrate tablets which are also effective at reducing stones.

Oxalate is generally not found in animal products while many plant foods are moderate or high, and some are extremely high (such as spinach, beets, beet greens, sweet potatoes, peanuts, rhubarb, and swiss chard). Despite this, a study from the Harvard School of Public Health found that people following a plant-based eating pattern had a lower occurrence of kidney stones ( 59).

There is no research on kidney stone frequency in vegans, though anecdotally I know of some who have gotten stones. Of course, I also know of meat-eaters who have gotten kidney stones. But is the average vegan at a higher or lower risk? Vegan diets are higher in some elements that increase the risk of stones, lower in some, and higher in some things that prevent stones, so it is hard to say.

The story regarding oxalate does not end with kidney stones. There is currently an entire community built around the idea that absorbing too much oxalate, known as enteric hyperoxaluria, either causes or exacerbates many diseases such as fibromyalgia, interstitial cystitis, vulvodynia, depression, arthritis, autism, and a variety of digestive disorders (which, in turn, exacerbate hyperoxaluria by allowing even more oxalate to be absorbed).

According to LowOxalate.info, leaky gut syndrome, in which molecules are absorbed from the digestive tract at a higher than normal rate, can cause hyperoxaluria. They also say that you cannot rely on getting a kidney stone as a warning sign before oxalate accumulates in other tissues.

There is not much research (on humans) regarding hyperoxaluria and diseases other than kidney stones and vulvodynia, so it is hard to say much about them with any certainty. However, many people have reported improved health on a low-oxalate diet and given the high amount of oxalate in some plant foods, it might be a good idea for vegans to be aware of this issue and not eat unusually high amounts of these foods.

Here are some other tips for minimizing problems from oxalate:

Boil high-oxalate leafy greens and discard the water.

Meet the RDA for calcium. Eat high-calcium foods or take calcium with meals; calcium citrate if you have a history of calcium-oxalate stones.

Drink plenty of fluid.

Do not include large amounts of high-oxalate vegetables in your green smoothies.

Do not take large amounts of vitamin C.

If you have a history of calcium-oxalate kidney stones or suspect you have hyperoxaluria, there are a few more things you can do such as limit oxalate as much as possible, add citrate to your diet (through orange or lemon juice, or calcium citrate), minimize added fructose and sodium, or try a probiotic supplement as described below.

Please see the Contents above for quick links to more details about all of these topics as well as tables of the oxalate content of foods and other helpful resources.

Background

Oxalate is a small molecule found in large amounts in many plants foods but not found in animal foods. Our bodies make oxalate as an end product of metabolism (primarily the metabolism of the protein amino acids glycine and serine, but also of vitamin C and possibly fructose). However, our bodies do not use oxalate in any way, nor degrade it, and it must be excreted through the urine or feces. Even if oxalate intake is zero, oxalate will be excreted in the urine as a result of normal metabolism.

Oxalate is made of two carbons and four oxygen with a charge of -2, making it attracted to other molecules with a charge of +2; especially calcium and to a lesser extent magnesium. When oxalate combines with calcium in urine, it becomes insoluble (i.e., a solid). If enough calcium-oxalate crystals form in the bladder, kidney stones can develop.

In the USA's National Health And Nutrition Examination Survey (NHANES) 2007-2010, the rate of having had a kidney stone was 10.6% for men and 7.1% for women ( 60). Approximately 25% of untreated patients experience a new episode within 5 years ( 60).

Calcium-oxalate is the most common form of kidney stones, accounting for about 75%. It is essential to determine the type of stone (calcium-oxalate, calcium-phosphate, uric acid, cystine, or struvite) as treatment methods can conflict.

An increased level of oxalate in the urine is a risk for calcium-oxalate kidney stones. For adults, this is considered to be above 45 mg per day.

When someone with a kidney stone is tested for various metabolic defects that can cause kidney stones (such as kidney problems that cause acidosis) and none are found, their kidney stone is labeled "idiopathic." A large proportion of kidney stones are considered idiopathic and they are typically calcium-oxalate.

A 2006 study from the University of Bonn compared oxalate absorption between 120 kidney stone formers and 120 non-formers on low-oxalate diets with equal amounts of oxalate (63 mg/day) and calcium (800 mg/day) ( 56). None of the participants had a history of digestive disorders (which can increase oxalate absorption). They found a small, but statistically significant difference in oxalate absorption between stone formers (10.2%) and controls (8.0%). There were no gender or age differences. Of the oxalate absorbed within 24 hours, 80-85% of it was absorbed within the first 6 hours after ingestion. Absorption values greater than 20% only occurred in the stone formers. When extrapolated to higher oxalate diets, the researchers believed that "Oxalate hyperabsorption may be the main reason for stone formation in more than half of the idiopathic calcium oxalate stone formers."

Another study found oxalate to be absorbed at a very low rate of .75 to 1.9% ( 35).

Based on 5 individuals, researchers from Wake Forest University estimated the daily intake of oxalate to be an average of 152 ± 83 mg, ranging from 44 - 352 mg/day. Samples of the food were analyzed for oxalate content; in other words, the amounts were not simply based on food tables ( 9).

Patients with idiopathic kidney stones tend to have high rates of osteopenia and osteoporosis. One study showed that 50% had osteopenia and 16% had osteoporosis ( 57). In another study, 56% of male and 50% of female stone formers had osteopenia while 10% of the men and 24% of the women had osteoporosis ( 58).

Hyperoxaluria

Hyperoxaluria is a condition in which the amount of oxalate in the urine becomes very high, so high that it can cause severe kidney damage. Oxalosis refers to oxalate deposits in the kidney.

There are two types of hyperoxaluria, primary and enteric.

Primary hyperoxaluria is a genetic disease in which the liver produces too much oxalate. It occurs in 1 out of 100,000 to 1 million people ( 1).

Enteric hyperoxaluria is when too much oxalate is absorbed from the digestive tract. This typically happens in cases of intestinal diseases and more rarely in cases of very high-oxalate diets.

In cases of hyperoxaluria, it is possible that the build-up of oxalate in the body can become so great that it doesn't just damage the kidneys, but can be deposited in other parts of the body. This has led to much speculation that people suffering from diseases other than kidney stones are actually suffering from an accumulation of oxalate in other tissues.

If you suspect that you are suffering from hyperoxaluria, you should talk to a health professional. The Mayo Clinic has some helpful information in their article Hyperoxaluria and oxalosis as does the Oxalosis and Hyperoxaluria Foundation (OHF).

Because kidney stones are rare in childhood, the OHF recommends that all children and adolescents who have symptoms of kidney stones be screened for hyperoxaluria ( more info)."

Current practice (as of October 2013) is that if a low-oxalate diet is adhered to but does not succeed in lowering urinary oxalate levels, the low-oxalate diet can be abandoned because dietary oxalate is not the cause. Very high-oxalate foods should still be avoided.

LowOxalate.info is a popular website that provides support for people suffering from hyperoxaluria. They suggest that hyperoxaluria may play a significant role in autism, COPD/asthma, and thyroid disease. They say that, "So far, our list of conditions that improve [upon reducing oxalate intake] includes fibromyalgia, interstitial cystitis, vulvodynia, depression, arthritis, and gut problems of all sorts, as well as autism and many other developmental disorders."

Of problems that do not involve the kidney that could be caused by hyperoxaluria, vulvodynia appears to be the most studied. Vulvodynia is when the vulva becomes very painful upon touch or pressure. Hyperoxaluria could lead to oxalate crystals forming in these sensitive tissues causing the pain.

There is a 1991 case report in the Journal of Reproductive Medicine, in which a woman who had suffered from vulvodynia for four years was given calcium citrate to reduce the oxalate levels in her body. After a year, she was pain-free. Upon discontinuing the calcium citrate, her symptoms returned only to disappear again after reintroduction of the calcium citrate ( 2).

A 1997 study from Good Samaritan Hospital in Cincinnati showed some mixed results on oxalate and vulvodynia ( 3). They were not able to predict vulvar pain by measuring oxalate excretion. However, a small number of women (5 out of 59) appeared to have cured their vulvodynia using 400 mg of calcium citrate 3 times a day, while 9 others improved.

A 1999 case-control study from the University of Michigan found that women with vulvar vestibulitis syndrome (VVS), a form of vulvodynia, consumed more high and medium rather than low oxalate foods, but there was no significant difference in average oxalate intake based on a questionnaire regarding the previous 4-weeks ( 75). Bacterial vaginosis, yeast infections, and human papillomavirus were strongly associated with VVS.

A 2008 study from the University of Minnesota found no association between oxalate intake in vulvodynia cases vs. controls when oxalate intake was divided into low, medium, and high (intake amounts were not reported; 4).

As for the other diseases listed by LowOxalate.info, there isn't much research:

A 2012 study from Poland found that blood and urinary oxalate were significantly higher in kids with autism. Trials are being conducted to see if a low-oxalate diet will improve symptoms (7).

Oxalate deposits are common in the human thyroid (8), but there was no more research than that.

Digestive disorders - Hyperoxaluria is common in Crohn's disease (see below), but is not considered to be a cause. I could not find any research on irritable bowel syndrome and very little on ulcerative colitis.

I found no research on asthma, arthritis, fibromyalgia, interstitial cystitis, or depression.

Digestive Disorders

Fat malabsorption results in unabsorbed fat forming insoluble soaps with calcium. This prevents calcium from being available to combine with oxalate in the gut, resulting in a higher oxalate absorption ( 52).

Short bowel syndrome, in which part of the bowel is surgically removed, is a common reason for fat malabsorption. Short bowel syndrome is common in people with Crohn's disease and in bariatric surgery.

People with cystic fibrosis are also at an increased risk of kidney stones ( 5, 6), likely due to pancreatic insufficiency leading to fat malabsorption and/or antibiotic therapy.

Patients with Crohn's are more likely to have hyperoxaluria, and this hyperoxaluria is more common in Crohn's patients who have had a bowel resection (part of their digestive tract removed). Such patients are at a higher risk of calcium-oxalate kidney stones and in some cases oxalosis results and can cause kidney failure.

The hyperoxaluria in Crohn's patients is thought to be caused by enteric hyperoxaluria (an increase of oxalate absorption), but could also be exacerbated by other factors, such as fat, vitamin B6, calcium, magnesium, and citrate malabsorption.

A 2012 study from Germany found that 28% of Crohn's patients had calcium-oxalate kidney stones. These patients had an average oxalate absorption rate of 23%, compared to 8% in the patients without kidney stones ( 42).

The authors of the study note a case in which a young woman with Crohn's suffered from end-state renal failure at age 34. Her first kidney transplant failed due to hyperoxaluria. Her second transplant succeeded due to extra pre-transplant hemodialysis and vitamin B6, and post-transplant fluids, citrate, and O. formigenes administration.

The authors conclude that "[T]he high prevalence of [kidney stones]/oxalosis in patients with Crohn's disease is based on secondary, enteric hyperoxaluria. Conservative treatment options are still scarce and only a high fluid intake plus careful dietary advice (low-oxalate and slightly enriched calcium diet) are the current therapeutic measures."

People with short bowel syndrome can suffer from a lack of bile acid absorption. A 2003 study from Baylor University provided patients with bile acid replacement therapy for 3 days resulting in significantly less urinary oxalate excretion, from 87 to 64 mg per day ( 52). In the one patient followed, 3 months of treatment (of not only bile acid replacement), resulted in a further reduction to 27 mg of oxalate excreted per day.

Natural bile acids are not vegan, but there is a synthetic version, cholylsarcosine, which also reduced urinary oxalate excretion from 87 to 73 mg per day in the 3-day Baylor University study. I was not able to determine if cholylsarcosine is vegan.

Vitamin C

Oxalate can be a byproduct of vitamin C metabolism. The RDA for vitamin C is 90 mg for adult men and 75 mg for adult women.

A 2004 report from the Health Professionals Follow-up Study found an increased risk of kidney stones among men getting more than 1,000 mg of vitamin C per day compared to those getting 90 mg/day or less (1.41, 1.11-1.80) ( 12). A 1999 report from the Nurses Health Study did not find an association between high vitamin C intakes (above 1500 mg) and risk of kidney stones ( 43).

Even though large amounts of vitamin C can be broken down into oxalate, and people at risk for kidney stones should not take vitamin C tablets, this does not necessarily mean they should not drink orange juice, which contains other molecules that can be beneficial for kidney stones, especially potassium and citrate.

Fructose

The Health Professionals Follow-up Study found an association between total fructose intake and risk of kidney stones in men (1.28. 1.06-1.55) for highest versus lowest fructose intake of 13.8% vs. 5.6% of calories. The Nurses Health Study I (of older women) and II (of younger women) found similar results. Similar results were found for absolute amounts of fructose, and not just as a percentage of calories ( 55).

In a 1995 study, researchers from France found that giving fructose intravenously caused an increase in urinary oxalate, while glucose did not ( 76). Interestingly, an oral load of fructose had the opposite effect, reducing urinary oxalate. Fructose also increased uric acid levels in the blood, but not in urine, which could be relevant to uric acid kidney stones.

Vitamin B6

Vitamin B6 deficiency could possibly play a role in hyperoxaluria. The authors of a paper on Crohn's say, "It is known that in states of low serum vitamin B6, the cofactor of the glyoxylate transaminating liver enzyme alanine:glyoxylate-aminotransferase (AGT), may lead to accumulation of peroxisomal glyoxylate, which is later oxidized to oxalate ( 42)."

In a 1996 report, the Health Professionals Follow-up Study did not find an association between vitamin B6 intake and kidney stones, comparing men consuming 40 mg per day to those consuming less than 3 mg (who had an average intake of 2 mg) ( 44). A 2004 report from that study also found no association after 14 years of follow-up ( 12). The RDA for vitamin B6 is only 1.3 mg for adults 18 to 50 years old and 1.7 for men over 50, so very few, if any, of these men were likely suffering from vitamin B6 deficiency.

A 1999 report from the Nurse's Health Study also did not find an association between low vitamin B6 intake and kidney stones, but the lowest intake level met the RDA so, again, there were probably few people in the study with B6 deficiency ( 43).

Fungal Infections

An article by Dr. William Shaw of The Great Plains Laboratory, Oxalates: Test Implications for Yeast & Heavy Metals, suggests that fungal infections could produce a high oxalate burden on the body. I could not find much research on humans regarding this, but it's something people with fungal infections might want to consider or talk to their health professional about.

Green Smoothies

Someone eating high-oxalate greens for green smoothies could end up with an unusually high oxalate intake which could possibly lead to a kidney stone.

In 2012, the Mayo Clinic reported on an 81-year old man with kidney failure apparently brought on by juicing high-oxalate vegetables in an attempt to lose weight. His dietary oxalate intake while juicing averaged 1,260 mg and ranged from 35 - 5,000 mg ( 10). He also had a high daily intake of vitamin C of 150 - 900 mg from his diet plus 2,000 mg from a supplement. His calcium intake was low, averaging 370 mg/day. All of these factors likely contributed to his oxalosis, and his age could have been a factor since kidney function decreases with age.

When you pull all this information together, the man created a perfect storm for kidney problems from a huge oxalate load, no boiling out of soluble oxalate (more info below), large amounts of vitamin C, and a low calcium intake limiting the creation of insoluble oxalate in his digestive tract (more info below).

Apparently, there are numerous anecdotal reports of people who take up green smoothies and subsequently develop kidney stones.

Is the Average Vegan at Risk for Kidney Stones?

A 2014 study from EPIC-Oxford measured the risk of being hospitalized for a kidney stone over the course of five years for people in various diet groups ( 77). Vegetarians (including vegans) had a 31% lower risk (.69, .48-0.98) as compared to high meat-eaters.

While people who have had calcium-oxalate kidney stones need to watch their oxalate intake, the evidence that a diet moderately high in oxalate puts the average person at risk for kidney stones is not strong.

The Health Professionals Follow-up Study (HPFS) and the Nurses' Health Studies I and II are two of the of largest and best designed prospective studies on nutrition and health. In 2007, they reported an increased risk of kidney stones for men between the highest one-fifth of oxalate intake (median of 328 mg/day) compared to the lowest one-fifth (median of 106 mg/day) of 1.22 (1.03- 1.45). For older women, the risk for the highest one-fifth (median of 287 mg/day) compared to the lowest one-fifth (87 mg/day) was 1.21 (1.01-1.44). There was no association for younger women. Being below the median calcium intake of 755 mg/day strengthened the association a bit for men 1.46 (1.11-1.93) ( 30).

Despite the statistically significant findings, the author's conclude, "Our data do not support the contention that dietary oxalate is a major risk factor for incident kidney stones. The risk that was associated with oxalate intake was modest even in individuals who consumed diets that were relatively low in calcium."

To put this in some perspective, my calculations show that being in the highest one-fifth of oxalate intake would raise the risk of getting a kidney stone from age 20 to 70 from 17% to 21% ( 31) for men. These calculations are somewhat crude, assuming the risk is over 50 adult years and without adjusting for the fact that different fifths of this population had different risk rates, but they're probably in the ballpark.

The DASH Diet

Dietary Approaches to Stop Hypertension (DASH) is a diet high in fruits and vegetables, moderate in low-fat dairy products, low in animal protein, and usually low in sodium. This diet has been used to successfully reduce blood pressure in people with hypertension.

The Harvard School of Public Health thought that a DASH eating pattern might help prevent kidney stones so they tested it in their three big cohorts (Health Professionals Follow-up Study and the Nurses Health Studies I and II) ( 59). They found that those eating a DASH-like diet pattern at baseline had about half the risk of kidney stones. Comparing the highest one-fifth to the lowest, in regards to DASH score, the rates were .55 (0.46-0.65) for men, 0.58 (0.49-0.68) for older women, and 0.60 (0.52-0.70) for younger women. The lower risk was independent of age, body size, hypertension, diabetes, thiazide use, and intakes of total calories, fluid, caffeine, and alcohol. The type of kidney stone was not determined in this study, but it can be assumed that most were calcium-oxalate.

Animal protein ended up not varying much across the groups, so that wasn't the protective factor. Calcium went up with higher DASH scores, but even at low calcium intakes, higher DASH scores had lower rates of kidney stones.

The researchers state:

The consistent association between consumption of a DASH-style diet and lower kidney stone risk in all three cohorts is remarkable considering the substantial differences we previously observed in individual dietary factors and risk between men (HPFS), older women (NHS I), and younger women (NHS II).

Although we think it reasonable for calcium oxalate stone formers with high levels of urinary oxalate to avoid intake of some individual foods very high in oxalate (such as spinach and almonds), our data do not support the common practice of dietary oxalate restriction in calcium stone formers, particularly if such advice results in lower intake of fruits, vegetables, and whole grains.

Oxalate and a Vegetarian Diet

There are no studies measuring oxalate levels or kidney stone risks in vegans. However, there are some trials investigating the effects of a vegetarian diet on kidney stone risk.

In 1979, researchers from the General Infirmary in Leeds, UK, asked, "Should recurrent calcium oxalate stone formers become vegetarians?" ( 16) These researchers wanted to investigate the connection between animal protein and kidney stones.

Twenty-four-hour urines were collected from 22 lacto-ovo vegetarians (10 male and 12 female) and analyzed for 6 risk factors. The vegetarians had a slightly lower risk of forming stones than meat-eating women, a bit more than meat-eating men, and a lot lower than previous stone formers. Urinary oxalate excretion for the vegetarians was about 27.8 mg/day compared to about 44.4 mg/day for recurrent stone formers.

In 2002, researchers from the University of Bonn in Germany studied the effects of four different diets on the urine of 10 men with no history of kidney stones ( 17). All the men ate each diet for a period of five days each. The diets included:

The men's standard diet (SD)

A typical Western diet of high energy, alcohol and purine content, excess protein, and low fluid (WD)

Normal diet (ND)-not really defined but supposedly healthier than the WD

A lacto-ovo vegetarian diet (VD)

All the test diets contained about 800 mg of calcium.

The risk of calcium oxalate crystallization was highest on the SD and WD diets with no difference between the ND and VD. The VD had lower urinary calcium, which lowers stone risk, but higher urinary oxalate. The authors suggested that on a vegetarian diet, calcium intake should be even higher than 800 mg to help bind more oxalate in the digestive tract.

A 2008 study was conducted by the Bonn researchers on 8 healthy volunteers (3 men, 5 women) with no history of kidney stones ( 18). Each person took turns eating a low-oxalate omnivore diet, a low-oxalate (70 mg) vegetarian diet, and a high-oxalate (300 mg) vegetarian diet.

The researchers were surprised that the higher oxalate vegetarian diet resulted in less oxalate absorbed and excreted through the urine than the low-oxalate vegetarian diet (see Table 1). They attributed it to the fact that the highest oxalate meal (251 mg from spinach) in the high-oxalate diet contained a cream sauce providing 212 mg of calcium, which could have negated the higher oxalate load. This seems reasonable, but there is still a question as to why more oxalate was excreted in the urine and the supersaturation was higher on the low-oxalate diet. In any case, the researchers believed that a vegetarian diet must contain enough calcium at meals to prevent oxalate absorption if they are going to be prescribed for people with kidney disease, though I don't see how that could be concluded from this study.

The authors were also concerned about the binding of calcium by phytate in high-oxalate vegetarian meals as this could reduce the available calcium for binding with oxalate. Other research has shown that unless phytate is present in unusually high amounts, such as in wheat bran, it probably does not bind much calcium ( 19).

In summary, the research seems to indicate that if oxalate is not higher than 300 mg and calcium intake is adequate, the average plant-based eater should not be at a higher risk for kidney stones than the average person.

Decreasing Absorption of Oxalate from Foods

Soluble vs. Insoluble

Oxalate in food is either soluble or insoluble. Insoluble oxalate is bound to another molecule that makes it much harder to absorb; normally calcium but also sometimes magnesium. Calcium supplements are often recommended for oxalate kidney stone patients to bind with oxalate and be excreted (more info below).

Soluble oxalate is not attached to another molecule and is more easily absorbed.The intake of soluble oxalate might be much more important than total oxalate.

For example, in a 2008 study from the University of Wyoming, subjects without a history of kidney stones were given just over 1 teaspoon of cinnamon (3.5 g) or 3.2 g of turmeric, each providing 63 mg of oxalate, broken into 3 doses per day for 4 weeks with meals ( 41). In turmeric, 91% of the oxalate was soluble, while only 6% of the oxalate in cinnamon was soluble. Turmeric caused significantly higher urinary oxalate for the 6-hour and 22-hour tests, while cinnamon did not show a significant increase.

It is, however, at least theoretically possible that if someone has a "leaky gut", where there are gaps in the junctions between cells in their intestinal walls, they could absorb large amounts of both soluble and insoluble oxalate.

A number of studies have found that boiling plants allows much of the soluble oxalate to escape into the boiling water which can then be discarded ( 13). University of Wyoming researchers measured the oxalate levels in a variety of vegetable using different cooking methods ( 14). Boiling reduced total oxalate levels by a decent amount, steaming to a lesser extent (Table 2). The study showed that the majority of the oxalate lost was soluble.

The authors write, "There was a significant loss of soluble oxalate in almost all test vegetables by boiling, ranging from 30 to 87%. It also appears that oxalate is much easier lost from leaves than from stalks and roots."

One caveat to this study is that many of these vegetables were cooked for a much longer time than might be typical. For example, spinach was boiled for 12 minutes, which seems to be at least twice as long as a normal boiling time.

Table 2. Oxalate Content (mg per 100 g wet weight)

Dietary Calcium

Adding calcium to meals could decrease the available soluble oxalate resulting in less oxalate absorbed.

A 2003 study from Lincoln University in New Zealand measured the oxalate absorption from spinach with calcium added to the diet ( 35). The spinach contained 957 mg of oxalate, of which 737 mg was soluble. The spinach was grilled to prevent loss of soluble oxalate into cooking water. The spinach contained 90 mg of calcium, of which 69 mg was bound to oxalate. The mean bioavailability of soluble oxalate in the grilled spinach was 0.75 ± 0.48% over a 6-hour period after intake and was 1.93 ± 0.85% measured over a 24-hour period. Adding 117 mg of calcium from sour cream reduced the 6-hour oxalate absorption to .52%. Adding 480 mg of calcium from sour cream and milk reduced the absorption to .14%. Adding 80 mg of calcium from cottage cheese did not reduce absorption.

In a 1993 report, the Health Professionals Follow-Up Study (men) found an increased risk of kidney stone in the lowest one-fifth of calcium intake of < 605 mg/day compared to all other fifths, the highest category having a median intake of 1,326 mg per day ( 36). Animal protein intake was also associated with a higher risk of kidney stones, whereas potassium and fluid intake was associated with a lower risk. Sodium, magnesium, phosphorus, sucrose, and fiber were not associated with risk.

A 1997 report from the Nurse's Health Study I, conducted on older women, found that the highest one-fifth intake of dietary calcium (not including supplements, median intake of 1,303 mg/day) was associated with a significantly lower risk of kidney stones than the lowest intake (median 391 mg/day) ( 37). Supplemental calcium didn't fare as well; it increased risk (1.20, 1.02-1.41). Sucrose and sodium intake were associated with an increased risk, while potassium and fluid were associated with a decreased risk. Intake of animal protein, phosphorus, and magnesium were not significantly associated with risk.

A 2004 report from the Nurse's Health Study 2, conducted on younger women, found that those in the lowest one-fifth of dietary calcium (median 540 mg/day) had a higher risk of kidney stones compared to the highest one-fifth (median 1,300 mg/day) ( 38). There was a statistically significant trend towards lower kidney stones among the intermediate categories. Supplemental calcium was not associated with a reduced risk. Animal protein was marginally associated with decreased risk. Phytate and total fluid intakes were significantly related to reduced risk. Sucrose intake was associated with an increased risk, while the intakes of sodium, potassium, magnesium, and phosphorus were not independently associated with risk.

The researchers said that most of the women were not taking their calcium supplements with meals and this could explain why the supplements were not reducing their risk ( 38).

Degradation by Intestinal Bacteria

There are a number of common intestinal bacteria that degrade oxalate, reducing the oxalate load of the body. Oxalobacter formigenes is the most studied of these bacteria.

A 2012 paper from Wake Forest University reports that the rates of people who have O. formigenes in their digestive tracts range from from 38% in the USA to 77% in Korea ( 20). They say, "Colonization rates are much lower in diseases where the bowel is affected, such as inflammatory bowel disease and cystic fibrosis. Such patients are known to have increased oxalate excretion and supersaturation of calcium oxalate, and are also at risk for developing kidney stones."

One reason some people might have high levels of oxalate is that antibiotic therapy has killed the O. formigenes in their digestive tract. There are a number of strains of O. formigenes and some are sensitive to some antibiotics while others are not. The Wake Forest University team determined that all four O. formigenes strains they tested were resistant to amoxicillin, amoxicillin/clavulanate, ceftriaxone, cephalexin, and vancomycin. All four strains were sensitive to azithromycin, ciprofloxacin, clarithromycin, clindamycin, doxycycline, gentamicin, levofloxacin, metronidazole, and tetracycline. One strain was resistant to nitrofurantoin while the others were sensitive ( 20).

Being sensitive to an antibiotic in vitro does not necessarily mean that someone's O. formigenes will be wiped out by treatment with that antibiotic. A 2011 study by New York Harbor Veterans Affairs Medical Center and Bellevue Hospital found that 7 out of 16 patients receiving amoxicillin/clarithromycin were still colonized with O. formigenes after 6 months, whereas 2 treated with metronidazole/tetracycline/bismuth and 1 treated with metronidazole/clarithromycin were not ( 21).

A 2008 case-control study conducted with patients from hospitals from Boston and North Carolina found that only 17% of people with recurrent kidney stones had O. formigenes in their stool, compared to 38% of the control group ( 22). The presence of O. formigenes among cases was highest in the one-third with the highest oxalate intake. Based on a number of other findings in the study, the researchers suggest that O. formigenes may prevent a post-meal spike in urinary oxalate while not doing much to change the total urinary oxalate over a 24-hour period. There is some thought that urinary oxalate spikes are more important than overall oxalate loads in contributing to stone formation.

A 2011 study from Wake Forest found that 24-hour urinary oxalate excretion was 20% lower on a low calcium (400 mg), moderate oxalate (250 mg) diet in people colonized with O. formigenes ( 23). This indicates that when calcium intake is low, O. formigenes might have more of an impact. Higher calcium intakes reduced the amount of O. formigenes, indicating that calcium may bind with oxalate and prevent the feeding of O. formigenes.

In a 2013 study, Bonn researchers found that among kidney stone formers, O. formigenes did not decrease the amount of oxalate absorbed into the body. However, blood oxalate levels were significantly lower in stone formers colonized with O. formigenes (1.70 µmol/l) than in those who were not colonized (5.79 µmol/l). The researchers theorized that rather than affecting oxalate absorption, O. formigenes degrades oxalate in the intestines thus increasing oxalate secretion from the intestinal cells into the intestines, lowering the blood oxalate levels and, hence, lowering urinary oxalate levels ( 24).

There is the possibility that people with high oxalate intakes can adapt by increasing the amount of oxalate degrading bacteria. A 2005 study from Germany, of only 4 people, indicated that over the course of six weeks, the percentage of oxalate absorbed is about the same as on a low-oxalate diet of 63 mg per day, about 7-10% ( 45). However, 10% of 600 mg is still about 10 times as high as 10% of 63 mg (6 vs. 60 mg absorbed). Two of these subjects tested positive for O. formigenese.

Probiotics

Other bacteria may play a role in oxalate degradation in the intestines, including Eubacterium lentum, Enterococcus faecalis, Lactobacillus acidophilus ( 25), and Bifidobacterium lactis ( 26).

As of November 2013, there were no probiotic supplements with O. formigenes, though one company, OxThera, is in the process of creating one.

Liebman & Al-Wahsh reviewed the research on the probiotic supplements that have been tested to see if they reduce oxalate load ( 25). There were 6 studies, but they were fraught with different variables. Positive results were obtained by using the VSL#3 preparations from the company Oxadrop. Their current preparation (November, 2013) of VSL#3 contains:

Bifidobacterium breve

Bifidobacterium longum

Bifidobacterium infantis

Lactobacillus acidophilus

Lactobacillus plantarum

Lactobacillus paracasei

Lactobacillus bulgaricus

Streptococcus thermophilus

This preparation taken at a dose of 800 billion bacteria, once a day, dissolved in water after the last meal of the day for 4 weeks, reduced urinary oxalate excretion by 33% ( 27). A follow-up test compared a 450 billion dose of VSL#3 to a 900 billion and found better results with the 900 billion but it wasn't statistically significant ( 28).

Decreasing Calcium-Oxalate Formation in the Kidney for Stone Prevention

Fluid

Many studies have found that higher fluid intake is associated with a lower risk of kidney stones (see the section under calcium for a few such studies).

A 1996 case-control study from Italy compared 24-hour urinary fluid between stone-formers and matched controls ( 54). Male stone formers urinated an average of 1.06 L per day compared to 1.40 L from non-stone formers, while female stone-formers urinated an average of .99 L compared to 1.24 L in non-stone formers.

In fact, it might only take increasing fluid intake by about a liter (4.2 cups) per day to significantly reduce the chances of a second calcium-oxalate kidney stone. That same study from Italy took the stone-formers and divided them into two groups, those receiving no treatment other than increased fluid and those receiving no treatment at all. After 5 years, only 12 out of 99 had relapsed in the fluid group compared to 27 out of 100 in the untreated group. The fluid treatment group had raised their fluid output by about 1.0 to 1.5 L over the course of the five years. ( 54)

Citrate

Hypocitraturia, which is low levels of citrate in the urine, increases the risk of kidney stones. Citrate combines with calcium in the kidneys to form a soluble complex resulting in less free calcium available to combine with oxalate (or phosphate).

Hypocitraturia is defined as < 320 mg (1.67 mmol) urinary citrate/day ( 62). However, a 24-hour urinary citrate concentration of ≥ 600 mg (3.12 mmol) is closer to the amount in healthy, non-stone forming individuals ( 62). Interventions to increase urinary citrate are a primary focus of the medical treatment of kidney stones ( 62), usually with potassium citrate.

Chronic diarrhea is thought to contribute to low urinary oxalate.

A 1986 cross-sectional study from the University of Chicago determined that the calcium to citrate ratio in the urine was the most important marker distinguishing the urine of people with kidney stones from those without, with higher ratios among the stone formers ( 32). Other markers that did not predict stone-formers as well included calcium alone, citrate alone, oxalate, sodium, and even the concentrated product ratio (CPR) which is a measure of calcium saturation.

A 2013 cross-sectional study from Spain had a similar finding ( 33). Kidney stone patients had low citrate levels in 32% of cases compared to 14% in the control group. They also found low urine citrate to be the best stone-related marker for predicting loss of bone mineral density. Oddly, they did not measure urinary oxalate levels.

Potassium Citrate

Potassium citrate is a pharmaceutical used to treat kidney stones, especially in cases of hypocitraturia ( 34) or recurrent stones. In addition to lowering the rate of kidney stones, potassium citrate has been shown in two studies to increase bone mineral density in kidney stone formers ( 51, 57)

It is important to find out what type of kidney stone you have because treatment with potassium citrate can raise the urine pH which can exacerbate calcium-phosphate (aka brushite) kidney stones (especially if it gets above 7.0). Potassium-citrate treatment should only be taken under medical supervision.

Calcium Citrate

Calcium citrate supplements are recommended for preventing calcium-oxalate stones by some experts. The University of Wisconsin-Madison Health and Nutrition Education handout for preventing oxalate kidney stones says, "While calcium carbonate and calcium citrate supplements are both useful for binding oxalate in the gastrointestinal tract, calcium citrate supplements are recommended as they seem to help kidneys excrete urinary citrate and decrease your risk for calcium stones ( 40)."

A 1994 study by Cornell University gave 1,000 mg of calcium, in the form of calcium citrate, to 14 women for 6 months as treatment for low bone mineral density in previous kidney stone formers ( 48). Participants were instructed to avoid high-oxalate foods and avoid excessive amounts of animal protein. After one month, urinary calcium and citrate increased. After six months, urinary calcium had dropped a bit compared to 1-month and parathyroid hormone and active vitamin D were significantly lower (indicating the body was no longer signaling the need for high calcium absorption). Calcium-oxalate supersaturation didn't change significantly over the course of the study, though it was slightly lower at the end. Apparently, no participant developed a stone during the 6 months, though this was not explicitly stated, and, oddly, the paper did not report whether calcium citrate increased bone mineral density.

The authors believed that this study showed calcium citrate supplements to be safe for women with low bone mineral density who have had kidney stones, but cautioned that it was a small study and might not apply to women who are overweight or not adhering to a low-oxalate diet.

A 2004 study from the University of Texas Southwestern Medical Center tested potassium citrate, calcium citrate (400 mg of calcium twice a day), and a combination of each for 2 weeks on women who were not stone formers ( 50). Calcium citrate lowered oxalate excretion while potassium citrate lowered calcium-oxalate saturation.

As of December 2013, there were not many calcium citrate supplements that do not contain vitamin D3 as cholecalciferol which is not vegan. However, there are some pure calcium citrate powders on the market:

Beverages

Because potassium citrate can have some side effects and comes in large tablets that are inconvenient to take, researchers have studied various beverages to see if there are any that could replace potassium citrate treatment. Orange juice was a candidate because it is high both in potassium and citrate, though it also contains some oxalate and vitamin C.

The research, which is summarized below, indicates that orange juice and lemon juice (or lemonade) can decrease the risk for stones, though about 6 g per day of citrate is necessary. See the table below for citrate amounts. Grapefruit juice and cranberry juice are most likely neutral.

Beverages and Stone Occurrence

In 2013, following up on the earlier work in their cohorts ( 61), Harvard School of Public Health compared those drinking from < 1 serving/week to > 1 serving/day of many beverages. The occurrence of kidney stones were affected in the following ways ( 60):

Decreased - coffee, decaffeinated coffee, tea, red wine, white wine, beer, orange juice

No effect - artificially sweetened cola, artificially sweetened noncola soda, liquor, apple juice, grapefruit juice, tomato juice, whole milk, skim milk, water

Increased - sugar-sweetened cola, sugar-sweetened noncola soda, punch

A 2007 study from Duke University found that daily treatment with 120 ml of concentrated lemon juice mixed with 2 liters of water (5.9 g of citric acid total) raised urinary citrate from 350 to 733 mg per day ( 67). The lemonade treatment reduced stone incidence from 1.0 to .13 stones per person per year. There was a control group receiving potassium-citrate therapy, but the stone incidence was not measured for them.

Beverages and Stone Markers

A 2006 study from the University of Texas Southwestern Medical Center found that 2.1 g of citrate, 3 times per day, of orange juice almost doubled urinary citrate while 2.1 g of citrate from lemonade had no impact ( 11).

A 1994 study from the University of Texas Southwestern compared one week of placebo, potassium citrate, and orange juice in participants with a history of hypocitraturia and kidney stones and participants with no history ( 74). Each participant went through all three treatments. The results were similar in both stone formers and non-stone formers, so they combined the results. The orange juice provided 11.6 g of citrate per day. They did not compare baseline levels to treatment levels. Both potassium-citrate and orange juice treatment increased citrate more than the placebo and about the same amount (to about 950 mg per day). Orange juice treatment raised urinary oxalate compared to the other two groups (26 mg to 34 mg per day). However, calcium intake on these diets was kept low at 400 mg per day; on a normal calcium diet, oxalate might not increase. The authors thought perhaps the small amounts of oxalate in orange juice, the carbohydrate, or the vitamin C might have contributed to the higher oxalate levels.

A 2007 study from the University of Wisconsin found that 4 oz of lemon juice or 32 oz of lemonade per day (they assumed each contained 5.9 g) increased urinary citrate levels of patients who had experienced kidney stones from 683 mg/day to 886 mg/day ( 65). Another group was treated with the lemon therapy and also potassium citrate and increased their citrate levels from 364 mg/day to 700 mg/day.

A 2007 study from Walter Reed Army Medical Center found that 4.5 g of citrate in lemonade, spread over 3 doses per day, barely raised citrate levels from 263 to 309 mg/day ( 66).

A 1996 study for University of California San Francisco gave lemonade to stone formers with hypocitraturia containing 5.9 g of citric acid per day ( 73). Urinary citrate increased significantly from 142 to 346 mg per day. Urinary oxalate decreased from 53 to 43 mg per day.

A 2003 study from Germany found that grapefruit, apple, and orange juice only slightly raised citrate levels ( 70). However, the participants did not have hypocitraturia and were not stone formers. Only grapefruit juice succeeded in reducing calcium-oxalate saturation to a statistically significant degree, though the other juices reduced it slightly.

A 2002 study from Italy found that grapefruit juice diluted to 10% with mineral water (to provide 2.1 g of citrate) slightly increased hourly urine citrate levels ( 71). When compared to mineral water only, the diluted grapefruit juice raised urine citrate levels a statistically significant amount, but that was because the mineral water-only treatment actually reduced citrate levels.

A 2001 study from the New York Veterans Affairs Medical Center tested 3 doses of 240 ml (about a cup) per day of grapefruit juice on non-stone formers ( 72). Urinary citrate and potassium levels increased, but so did oxalate. The researchers did a test to determine that the oxalate did not come from vitamin C (in the kidneys, anyway). Calcium-oxalate saturation increased slightly, but not to a significant degree on the grapefruit juice treatment.

A 2005 study from University of Texas Southwestern Medical Center tested cranberry juice ( 53). They gave stone and non-stone formers 2.3 g of citrate per day in 1 liter of cranberry juice broken into two doses. Urinary citrate actually decreased from 490 to 470 mg/day in stone formers. It also decreased in non-stone formers. The cranberry juice had a positive effect on markers of uric acid stones but not for calcium-oxalate stones. They reported that one other study showed an increase ( 68) and one showed no change in citrate excretion using cranberry juice ( 69). It seems safe to conclude that cranberry juice should not be the beverage of choice in preventing calcium-oxalate kidney stones or correcting hypocitraturia.

Table 2 shows the amount of citrate in various beverages as measured by researchers at the University of Wisconsin ( 62), and Duke University and Brown University ( 63). Various brands of lemonade and limeade were all lower.

Sodium

Restricting sodium might help prevent calcium-oxalate stones. A calcium atom is typically excreted with each sodium atom, so if you are urinating a lot of sodium, your urine is going to contain more calcium (other things being equal), providing a chance for calcium to bind with oxalate.

To my knowledge, there are no clinical trials using sodium restriction as the main treatment to prevent kidney stone recurrence, though one trial from Italy found that reducing sodium intake from 5,244 mg to 1,564 g per day decreased urinary calcium and oxalate ( 39).

Iron Absorption

Theoretically, oxalate should be able to bind to plant iron, especially when iron is in the ferrous (Fe ²⁺) state and prevent its absorption. There has not been much research. A 2008 study from Switzerland examined iron absorption from bread in meals containing spinach or kale with a whopping amount of 1,260 mg of added oxalate. They concluded that oxalate does not inhibit iron absorption ( 29).

Oxalate Content of Foods

The amount of oxalate in foods is hard to pin down. In a 2007 review of oxalate in the Journal of the American Dietetic Association, Massey reports that the part of the plant (stem vs. leaf, bran vs. endosperm), genetic differences between plant cultivars, soil conditions, and time of year harvested can account for differences in oxalate amounts ( 30). Massey noted that "[T]he differences in oxalate content of the final food due to modification of cultivation conditions are usually quite modest compared to the oxalate differences in cultivars. Therefore, breeding of commercially viable low oxalate cultivars seems a more promising approach to reducing oxalate in foods."

As described in the section on Soluble vs. Insoluble, the cooking method can also make a big difference in foods with a high content of soluble oxalate (which might be the only type that is absorbed at a significant rate in most people). Boiling or steaming and discarding the water can reduce the amount of oxalate, especially in the leaves of leafy greens.

Please see the table Calcium and Oxalate Content of Foods for the oxalate amounts in foods reported in the scientific literature or by the USDA. Unfortunately, there are many foods which are not included and there is much talk in the low-oxalate community suggesting the "old" methods of testing oxalate amounts in foods is inaccurate. I'm working on sorting this out.

In the meantime, here are two alternative tables which list more foods:

Other Resources

References

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46. Oxalic Acid Content of Selected Vegetables. Gives amounts of oxalate in 100 g of the raw, unprepared food (according to correspondence with the USDA Nutrient Data Library 05/13/2013).

47. Weaver CM, Heaney RP, Nickel KP, Packard PI. Calcium Bioavailability from High Oxalate Vegetables: Chinese Vegetables, Sweet Potatoes and Rhubarb. Journal of Food Science. 1997 May;62(3):524-5.

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Also Reviewed
Allie-Hamdulay S, Rodgers AL. Prophylactic and therapeutic properties of a sodium citrate preparation in the management of calcium oxalate urolithiasis: randomized, placebo-controlled trial. Urol Res. 2005 May;33(2):116-24. Abstract. Borghi L, Schianchi T, Meschi T, Guerra A, Allegri F, Maggiore U, Novarini A. Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria. N Engl J Med. 2002 Jan 10;346(2):77-84.
Clinical trial in which low-calcium diet increased risk of kidney stones.
Fishbein GA, Micheletti RG, Currier JS, Singer E, Fishbein MC. Atherosclerotic oxalosis in coronary arteries. Cardiovasc Pathol. 2008 Mar-Apr;17(2):117-23. Ramsubeik K, Keuler NS, Davis LA, Hansen KE. Factors Associated with Calcium Absorption in Postmenopausal Women: A Post Hoc Analysis of Dual-Isotope Studies. J Acad Nutr Diet. 2013 Oct 24. doi:pii: S2212-2672(13)01278-1. 10.1016/j.jand.2013.07.041. [Epub ahead of print]
Dietary fat has consistently been associated with higher calcium absorption. Authors suggest possibly due to higher estradiol levels.
Siener R, Ebert D, Hesse A. Urinary oxalate excretion in female calcium oxalate stone formers with and without a history of recurrent urinary tract infections. Urol Res. 2001 Aug;29(4):245-8.
In female patients with recurring urinary tract infections (who had been treated with antibiotics), urinary oxalate excretion was significantly higher (0.374 mmol/day) than in women without urinary tract infections (0.308 mmol/day) (P < 0.05).

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by Jack Norris, RD * Last updated December 2013 Oxalate is a molecule many in the vegan community are familiar with for preventing the absorption of calcium. This article does not address that subject-info can be found in the section Calcium Absorption from Plant Foods.

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Meg Campbell

Based just outside Chicago, Meg Campbell has worked in the fitness industry since 1997. She's been writing health-related articles since 2010, focusing primarily on diet and nutrition. Campbell divides her time between her hometown and Buenos Aires, Argentina.

Unless it's one of the few that behaves neutrally, every food is either acid- or alkaline-forming in the body. In general, fruits and vegetables are alkalizing, while meat, most dairy and all sugary foods are acidifying. A high-alkaline diet can be beneficial to kidney stone sufferers, regardless of the type of stones their bodies make, because it emphasizes fruits, vegetables and whole grains over animal proteins. For those who suffer from oxalate-containing stones, it's also important to emphasize low-oxalate foods. Oxalate occurs naturally in almost all fruits and vegetables to some degree.

Video of the Day

Lemons and limes are two of the top most-alkalizing foods, despite their high citric acid content. Both also have a low oxalate content, so those prone to forming oxalate-containing kidney stones can incorporate them in their diets without restriction. Lemons are excellent sources of vitamin C, and good sources of potassium, folic acid and antioxidant flavonoids.

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Unless it's one of the few that behaves neutrally, every food is either acid- or alkaline-forming in the body. In general, fruits and vegetables are alkalizing, while meat, most dairy and all sugary foods are acidifying. A high-alkaline diet can be beneficial to kidney stone sufferers, regardless of the type of stones their bodies make,...

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Lactic acid bacteria - their uses in food (EUFIC)

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Lactic acid bacteria - their uses in food (EUFIC)

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Lactic Acid bacteria like acidophilus reduce oxalates in the colon.

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Lactic Acid bacteria like acidophilus reduce oxalates in the colon.

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Recipes that are suitable for GFCF and/or SCD are marked.

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A cautionary tale about eating high oxalate foods - Stop The Thyroid Madness

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A cautionary tale about eating high oxalate foods - Stop The Thyroid Madness

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Just a few years ago, my husband and I were doing some restoration in our kitchen and dining area, especially painting. As a result, I was eating "quick foods" daily and quite a lot for weeks on end, and one quick food in particular was cocoa-covered almonds. I reasoned with myself that nuts are good for me, and I was also getting my favorite food on top of it-chocolate in the form of cocoa.

Additionally, I was drinking a lot of black " sun tea" every single day, making it on the back deck every day or two. i.e. a high oxalate drink. I would also eat a raw spinach salad often to get my greens in, week after week-easy to fix. Another high oxalate food. And I would eat very dark chocolate on top of it all as a nice treat, daily and week after week. Another high oxalate food.
And after several weeks of these daily "convenience foods"..and a lot of them all the time...all hell broke loose.
What are oxalates?

Oxalate, aka oxalic acid, is a naturally-occurring and reactive molecular substance found in a variety of foods, especially if the food is related to plants. That can include all seeds and nuts, most greens, many fruits, even chocolate. Even the Vitamin C we supplement with, or the fructose in the fruits we eat, can convert to oxalate! And our body does a great job...usually...of ridding our bodies of unneeded oxalate. You have a very good bacteria which will digest it, turn it into something less irritating, and move it out via your stools.In fact, the body does such a good job that you may be the way I was-having never heard of it or any reason to think of it.

How oxalate can wreak havoc

But as happened to me, if your body is not getting rid of the oxalates you are over-consuming in foods...these powerful and very reactive molecules can cause a lot of problems. And here are some of the symptoms of excess oxalates:

painful or inflamed joints, similar to fibromyalgia or arthritis

burning urine flow

interstitial cystitis, aka burning bladder, often associated with hyperoxaluria (high levels of oxalate in the urine)

burning bowel movements

vulvodynia - external female genital pain or irritation

depression

leaky gut or all sorts of other gut problems

kidney stones i.e. oxalates combine with calcium to form these

developmental disorders in children, including autism

hives (rarer than the above, but what happened to me with huge massive ones-that's what led me to discover the oxalate issue)

chelating of toxic metals like mercury

A nasty pair-oxalate and calcium

When high oxalate foods are combined with calcium rich foods or supplements, you then create oxalate crystals. Picture razor sharp, jagged edges and you have oxalate crystals (see photo), which can cause a lot of pain as they are eliminated via your stools. These nasty crystals can also form in your lungs, or your kidneys, or your joints and bones, or blood vessels, and even your brain. And any of the latter can result in inflammation.

If oxalates combine with iron, you then have oxidative damage, plus your iron levels will go down. There is also some suspicion that excess oxalates can negatively affect your thyroid.

The solution if you have overdone your consumption of oxalates?

Experts state to switch to medium oxalate foods (you'll begin detoxing the oxalates), then make your way down to low oxalate foods (when you think you are ready)....and avoid the high oxalate foods! The following link has downloadable lists of the content of oxalate in foods: http://www.lowoxalate.info/recipes.html. Generally, high oxalate foods include almonds, spinach, beet greens, okra, sweet potatoes, dried figs, refried beans, lentils, pecans, peanuts and peanut butter, pistachios, sesame seeds, chocolate and cocoa, green peppers, blackberries, raspberries, grits, whole wheat flour products, bran and other cereals, black tea and instant coffee...and you'll see more in high oxalate lists, but you can especially trust the testing done by the Yahoo Low Oxalate group information over most lists.
A mistake I made: I switched immediately to low oxalate...and let me tell you, the detox was MISERABLE for weeks. Don't do what I did. Slow down. Start with medium oxalate goods. Let your body take care of it a little at a time. Support your liver and kidneys. It can take many weeks. But more importantly, do your own research!!! This is just my experience and information based on research I did.
Or, if you haven't crossed the line and don't want to, the answer is "moderation".

I have eaten chocolate, almonds, and nuts for years without an issue, simply because I didn't overdo it...until I did. So as with goitrogens and any other potentially harmful foods, the key is in moderation and not getting into a rut like Janie Bowthorpe tends to do-eating one favorite food over and over and over....

UPDATE: I did it to myself again!!

Just three years after I got myself into trouble as explained above, I did it again. I overate high oxalate foods like chocolate, over and over and over. As a result, I found myself with high ferritin-a key sign of inflammation-and thus low iron. And my particular sign again that my body was trying to get rid of excess oxalates?? Hives. And I had to go through the messy process of detoxing that high oxalate all over again, which isn't fun. The lesson that is underscored is not to eat the same thing over and over and over, day after week after month, which I tend to do if I like something....like dark chocolate. 🙂 Moderation is key!

More info:

An easy-to-read chart about the oxalate content in many foods: http://www.ohf.org/docs/Oxalate2008.pdf

Good overall website about the oxalate issue plus recipes: http://www.lowoxalate.info/

For detailed information on the oxalate problem: http://www.greatplainslaboratory.com/home/span/oxalates.asp

About oxalate-caused vulvodynia: http://thevpfoundation.org/

Oxalates and autism: http://www.westonaprice.org/health-topics/the-role-of-oxalates-in-autism-and-chronic-disorders/

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A cautionary tale about eating high oxalate foods-Hyperoxaluria - Stop The Thyroid Madness

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Just a few years ago, my husband and I were doing some restoration in our kitchen and dining area, especially painting. As a result, I was eating "quick foods" daily and quite a lot for weeks on end, and one quick food in particular was cocoa-covered almonds.

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Can you tell me what oxalates are and in which foods they can be found?

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Can you tell me what oxalates are and in which foods they can be found?

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Can you tell me about oxalates, including the foods that contain them and how are they related to nutrition and health?

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