You may have heard about oxalate dumping. But, what is oxalate dumping anyway? Who should be concerned about it and what is the research behind oxalate dumping?
What Is Oxalate?
First, what is oxalate itself?
Oxalate is a “non-nutrient” that is found in many healthy plant foods such as spinach, almonds, raspberries, and potatoes. Plants make oxalate as way to regulate calcium and for protection. (1) However, as far as we know, oxalate does not have a function for us humans.
Oxalate & Kidney Health
High levels of oxalate in the body are harmful.
High urine oxalate increases kidney stone risk. Oxalate can precipitate out of urine and form calcium oxalate kidney stones. (2)
Extremely high oxalate levels can cause kidney damage (or, oxalate nephropathy) in people who are susceptible. Bariatric or bowel surgery and inflammatory bowel disease (IBD) can cause high oxalate absorption, increasing risk for oxalate nephropathy. (3)
There also may be some connection between urine oxalate and Polycystic Kidney Disease (PKD). One study found that rats with PKD who had calcium oxalate crystals in their kidneys had faster growth of kidney cysts.(4)
This may seem pretty scary. Does this mean everyone should avoid oxalate?
Nope! Definitely not.
Why not you ask? A low oxalate diet has not been shown to reduce the risk, or improve these conditions.
In fact, diets that are very high in plant foods, that are likely very high in oxalate, have been associated with better kidney health. Diets that include lots of plants are associated with FEWER kidney stones, BETTER outcomes in kidney disease and LESS kidney disease. (5) (6) (7) (8)
Oxalate In ≠ Oxalate Out
How can this be? If oxalate is “toxic” to kidneys, shouldn’t we eat less of it?
Your body is a complicated place. Not everything you eat is absorbed. Plus, once a molecule is absorbed, it travels through the bloodstream where it interacts with thousands of other minerals and enzymes. Then, it gets metabolized in the liver, goes through the bloodstream again, is processed by the kidney and then excreted in urine.
Also, every food itself contains thousands of vitamins, minerals, compounds and phytochemicals that interact with each other and impact digestion, metabolism and health.
So, it is silly to cut out an entire food because of a single nutrient or compound. Whether it be oxalate, potassium, phosphorus or any other food component. Your diet is SO much more than one molecule.
That being said, high levels of urine oxalate are harmful to kidneys. But, many factors influence how much oxalate is in your urine. A low oxalate diet is not necessarily the best way to reduce urine oxalate.
Here are some of the things that impact urine oxalate.
Variable Intestinal Oxalate Absorption
The amount of oxalate absorbed from food is very different for different people. Some of this variability is due to other nutrients in foods we eat. Specifically, calcium, magnesium and fiber can reduce oxalate absorption. (9)
Calcium seems to have the biggest role hindering oxalate absorption. Calcium can bind with oxalate in the intestine and be excreted in feces, rather than get absorbed into the body.
In addition, some people tend to absorb more oxalate from food than others.
We are just starting to understand how the bacteria that live in your intestines impact kidney stones and oxalate. We know that people who have kidney stones have different kinds of gut microbiota. (15)
One bacteria in particular, aptly named Oxalobacter formigenes, exclusively uses oxalate for food. People who have this bacteria in their gut may have a 70% reduced risk of kidney stones. (16)
But, this is a fascinating and promising area of research! (20)
Liver Oxalate Production
Oxalate in your body doesn’t just come from food. The liver makes a large amount of oxalate. In fact, about half of the oxalate in your urine is from oxalate that your liver makes, not from food. (21)
The liver can make oxalate from a variety of molecules including vitamin C, certain proteins and fructose. (21)
What Is Oxalate Dumping?
Oxalate dumping is the unfounded theory that oxalate in cells will be “dumped” from your body when you start following a low oxalate diet. This theory suggests that oxalate has been building up in your body and will be “flushed” out once oxalate is removed from your diet. Advocates of oxalate dumping often suggest that oxalate should be slowly reduced in your diet to prevent them from getting “dumped” out of your body all at once.
Oxalate dumping is commonly discussed in communities that suggest oxalate is “toxic” and everyone should follow a low oxalate diet.
Oxalate Dumping Symptoms
People claim that the “symptoms” of oxalate dumping include everything from moodiness to bed wetting to painful bowel movements.
Here are common oxalate dumping symptom claims:
- Yeast flares
- Painful bowel movements or urination
- Rashes or hives
- Bed wetting
Again, no studies have been published to support oxalate dumping or that oxalate in food can cause these symptoms.
Oxalate Dumping & Arthritis
Joint pain is a commonly cited symptom of oxalate dumping. Although oxalate arthritis (or, oxalate arthropathy) does exist, it is incredibly rare and is only found in susceptible people. (22)
Oxalate arthritis usually only happens in people with primary hyperoxaluria. Primary hyperoxaluria is a genetic condition that causes your body to make excess oxalate and is very rare – only 1 in 58,000 people (or 0.0017%) have primary hyperoxaluria.
People who have had bariatric or other bowel surgery may also be at risk for oxalate arthritis.
Carnivore Diet & Oxalate Dumping
A “carnivore diet” is recommended as a remedy to oxalate dumping. A carnivore diet consists of exclusively meat, poultry, fish and some other animal products. Whereas a carnivore diet bans all fruit, vegetables, whole grains, nuts, seeds, and legumes.
Some claim that a carnivore diet will help oxalate dumping because meat and most animal products do not contain oxalate. So, this will reduce oxalate in the body.
This idea is ridiculous and harmful.
Not only is oxalate not a problem for most people, but a diet that is exclusively animal products would dramatically increase the risk of kidney stones. Ironically, the very high protein carnivore diet could increase urine oxalate because the liver can make oxalate from excess protein. (21) And, the lack of fruits and vegetables could exacerbate low urine citrate and pH, both of which can cause kidney stones. (2)
In fact, kidney stones are a well-known side effect in children who follow a ketogenic diet for epilepsy treatment. (24)
In addition, a diet of only animal products would likely be dangerously high in protein and saturated fat. It would also lack fiber and certain vitamins and minerals. A carnivore diet would increase risk of heart disease, kidney disease, high blood pressure, cancer, constipation and most other chronic health conditions. (25)(26)
Does Anyone Need a Low Oxalate Diet?
All of this being said, there are some people who should limit how much oxalate they eat.
However, this applies to very few people.
If you have a history of calcium oxalate kidney stones and have high urine oxalate, it is reasonable to cut back how much oxalate you eat. The American Urological Association recommends that only people with high urine oxalate cut back high oxalate foods. (27)
Importantly, even people with high urine oxalate should not completely remove oxalate from their diet. A zero oxalate diet would completely remove plant foods, which would result in unhealthful eating patterns.