Oxalates, Kidney Stones and the Gut
Oxalates are natural compounds found in some vegetables, fruits, nuts, and grains. They are also made by the human body, as well as by fungal and mold species. High calcium oxalate levels are the most common cause of kidney stones and they also may be implicated in a variety of other conditions and symptoms. For most people, oxalate levels are dictated by dietary oxalate intake, gut health, and the microbiome; notwithstanding certain genetic impairments or liver issues. While the most common strategy to reduce oxalate levels is a low oxalate diet, I find not many prescribing this diet understand or address the role of gut health and the microbiome. In many, addressing gut health and the microbiome may reduce oxalate levels without a restrictive diet.
Ruling Out the Need for A Low Oxalate Diet
To rule in or out the need for a low oxalate diet you should run an Organic Acids Test. Small elevations do not typically warrant a low oxalate diet. Moderate to high levels of oxalic acid do warrant at least a temporary change in diet. The presence of Glyceric or Glycolic acid may indicate your body’s own endogenous production of oxalates.
On this test we would also look for microbial contribution to oxalate levels - fungi and mold. And depletion of nutrients that would otherwise be supportive of ridding the body of oxalates.
Regardless of the state of your microbiome I never recommend daily or long-term juicing of high oxalate foods such as spinach or rhubarb. Avoid overconsuming nuts in place of balanced protein in-take.
You’ll notice that oxalate experts (and shopping lists) often discuss soluble vs. insoluble oxalates. Oxalate absorption into the bloodstream is limited to soluble oxalates. What makes oxalates soluble? pH and the concentrations of calcium, magnesium, and phosphate will dictate the solubility of oxalates. Soluble oxalates can be absorbed in the stomach, the small intestine, and the colon. In the colon, the amount of oxalates available to be absorbed will be dependent on the bacterial degradation of oxalates.
Depending on these factors, approximately 5-15% of dietary oxalates are absorbed in the average person, contributing to 20-40% of serum oxalates. Some individuals may be hyper-absorbers of oxalates due to surgeries removing parts of the intestine (particularly various weight loss surgeries) and diseases causing malabsorption, which may include celiac disease, inflammatory bowel disease, small intestine bacterial overgrowth and more. When fat is not absorbed in the small intestine, it will bind up calcium, so then calcium cannot bind to oxalates and prevent absorption. So conditions affecting the gallbladder may also result in increased absorption of oxalates. Oxalate absorption in the colon may increase to over 30% when there are digestive issues5.
Primary hyperoxaluria is a genetic condition resulting in the liver producing too much oxalates, though this is a rare disorder.
The body cannot break down oxalates once absorbed and they have to be excreted in the urine. If there are high amounts of oxalates in the urine, they can form crystals that can become kidney stones. If oxalate crystals accumulate in the bloodstream due to poor elimination through the kidneys, these crystals can be deposited in joints, heart tissue, skin, eyes, nerves, muscles and bones causing a variety of symptoms and conditions. This level of oxalate toxicity is typically considered rare and mostly associated with primary hyperoxaluria - the genetic condition. Although, I’ve seen in practice a couple people in pretty rough shape due to oxalate levels secondary to severe gut issues or a previous long-term diet high in oxalates.
In the health world lately there is a lot of attention on oxalates causing pain, fatigue, and a myriad of other symptoms. Oxalates are being blamed for everything from depression to Hashimoto’s. Never take on a low oxalate diet without proper testing nor without a game plan for slow release of oxalates. Always keep in mind the importance of your microbiome. The levels of Bifidobacterium, Lactobacillus, Oxalobacter formigenes and Bacillus are important for proper oxalate breakdown. Take into account your ability to digest fats and the degree to which you may be experiencing leaky gut.
A fecal fat test is a simple test to assess malabsorption
Consider a fecal calprotectin test to assess for GI inflammation
Consider breath testing to assess for small intestine bacterial overgrowth
Consider blood testing to assess for celiac disease
Consider endoscopy or colonoscopy to further assess for celiac disease or inflammatory bowel disease
Assess magnesium, B6 and calcium levels; which help reduce oxalate absorption
