Could Oxalate-Rich Superfoods be Causing Your Illness?
Considered as “good-for-you” foods, certain vegetables and fruits contain compounds known as “oxalates,” which can lead to health problems.
Many individuals striving for health incorporate superfoods like spinach, almonds, and sweet potatoes into their diets. However, for some people, these foods might exacerbate chronic health issues. The culprit suspected? Oxalate.
Oxalates are naturally occurring compounds present in numerous plant-based foods such as leafy greens, nuts, seeds, and certain fruits. They are also generated by the body.
Oxalates have stirred topics of interest and debate in the field of nutrition. While they aid plants in protecting themselves and regulating their minerals, they might impact human health in ways that are not fully comprehended yet.
Scientists have not pinpointed a specific purpose for oxalates in the human body, but the fact that we produce them naturally implies that there may be undiscovered functions.
For most individuals, consuming oxalate-rich foods as part of a well-rounded diet does not seem to pose issues. Nonetheless, accumulating evidence suggests that some people, especially those with specific genetic predispositions or gut health issues, may face higher health risks if they consume excessive oxalates.
The context of our modern lives might be what transforms these compounds into potential hazards for certain individuals.
A Case Study: Oxalate Overload
Sally Norton, a Cornell University nutritional science graduate, experienced multiple health issues for over three decades despite following what she believed to be a perfect diet. Her symptoms included chronic pain, digestive problems, thyroid dysfunction, arthritis, tendonitis, thin skin, and profound fatigue.
After trying numerous treatments without success, Norton’s health took a dramatic turn when she made one dietary adjustment—eliminating high-oxalate foods. This change led to significant improvements in her health, demonstrating how seemingly healthy foods can sometimes underlie unexpected health challenges.
What Are Oxalates?
Oxalic acid is produced from vitamin C, oxaloacetate, and glyoxylate. When this acid binds with minerals like calcium, potassium, or magnesium, it forms compounds known as oxalates, such as calcium oxalate, potassium oxalate, or magnesium oxalate. These oxalates can create tiny crystals within the body.
In plants, oxalic acid and oxalate crystals serve various roles in growth, pH regulation, protection from excessive calcium, photosynthesis, and heavy metal detoxification. However, the impact of oxalates in humans is more nuanced.
Oxalates are considered anti-nutrients as they can hinder the absorption of essential minerals such as calcium, iron, and magnesium.
Oxalates are mainly excreted from the body through urine. However, when renal clearance is inadequate, oxalates can accumulate and form crystals. A decrease in oxalate-degrading bacteria in the gut can also contribute to elevated oxalate levels.
These resulting crystals may gather in various body parts such as the heart, skin, joints, bones, and eyes. The most well-known oxalate crystals are implicated in the formation of kidney stones, with around 80% of these concretions being composed of calcium oxalate.
Calcium oxalate. Saiful52/Shutterstock
Despite oxalates being recognized for their negative effects, they are also naturally generated within the body, hinting at important roles that are not yet completely understood.
“Oxalate might be somewhat analogous to ammonia. Ammonia has very important functional purposes. It’s normal to have some ammonia. But if ammonia rises above a certain threshold, then it becomes neurotoxic and could cause fatigue and brain fog. Oxalate may be similar,” according to Chris Masterjohn, an independent researcher holding a doctorate in nutritional sciences.
Attaining a balance between oxalate production and elimination may be the key.
“Oxalate is something we mostly synthesize when the ideal operation of our enzymes is not working up to their capacity,” stated Masterjohn. A deficiency in vitamin B1 or vitamin B6 can elevate oxalate production as these vitamins are crucial for enzyme functionality. Lack of sufficient levels can result in the accumulation of certain compounds that can be converted into oxalates as an alternate metabolic pathway.
“The goal shouldn’t be to ensure that the body never produces any oxalate,” emphasized Masterjohn. “We don’t want it being synthesized at a rate that exceeds what we can eliminate because eventually, it surpasses a threshold that causes toxicity. And at a slightly higher point, it crosses a threshold that leads to crystallization.”
More research is essential to grasp the complexity of oxalate, but the current understanding highlights that oxalate, on the higher end of the normal range, is increasingly prevalent in modern society, potentially tilting towards becoming a net negative, as per Masterjohn.
Is Modern Life Creating an Oxalate Problem?
The influence of oxalates on health may have become more pronounced due to the confluence of contemporary factors.
Changes in Modern Food Supply
In the past, many high-oxalate foods were typically available seasonally. Nowadays, however, foods abundant in oxalates, such as spinach and almonds, are accessible throughout the year.
Couscous salad with spinach, almonds, pear, and feta cheese. Elena Hramova/Shutterstock
Shifts in Dietary Practices
Americans primarily used animal fats like butter and lard in cooking until the introduction of vegetable oils in the early 1900s. Presently, “the average American is consuming at least one-fourth, and some a third, of their diet as vegetable oils,” as noted by Dr. Chris Knobbe.
Vegetable oils such as soybean, safflower, and sunflower oil can lead to oxalate production in the body.
“Vegetable oils are rich in a type of fatty acid called polyunsaturated fatty acids,” mentioned Masterjohn. “Those are highly vulnerable to a type of damage that can occur in the body called oxidation. When they oxidize, they break apart into small pieces. One of those small pieces [glyoxal] may undergo several steps of metabolism to become oxalate,” he added.
Americans derive approximately 23% of their diet from grains, according to the U.S. Department of Agriculture Food Availability Data System. Wheat, barley, rye, teff, and brown rice are rich in oxalates. Generally, whole grains contain higher concentrations of oxalates than refined grains like white flour and white rice, as the bran, the outer layer of the grain where oxalates concentrate, is removed during the refining process.
High-dose vitamin C supplements might elevate oxalate levels in certain individuals, as per a clinical trial from 2003. Similarly, a study in Kidney International in 2006 discovered that when healthy individuals consumed gelatin, which contains hydroxyproline, an element of collagen, their urine exhibited higher oxalate levels. Low doses of gelatin did not have an impact, but with increasing quantities, there was a clear connection—the more gelatin consumed, the greater the oxalate excretion.
Chronic diseases are prevalent in modern society, affecting an estimated 129 million Americans, as per the Centers for Disease Control and Prevention. Chronic disease can heighten oxidative stress levels, which is believed to promote the generation of more glyoxal, a precursor of oxalate, and its conversion to oxalate.
Processed food, excessive antibiotic usage, and chronic stress can reduce gut microbiome diversity, causing an imbalance in the gut microbiota and elevating oxalate levels. For example, candida overgrowth in the gastrointestinal tract can contribute to oxalate production.
Inflammatory bowel disease, celiac disease, short bowel syndrome, and bariatric surgery are conditions associated with fat malabsorption that potentially lead to increased oxalate absorption, according to a review in Foods. Additionally, a study in Kidney Diseases from December 2023 correlated irritable bowel disease with heightened oxalate levels in the body.
The Impact of Gut Microbiota on Oxalate Levels
The reduction of oxalate-degrading bacteria might result in an elevation of oxalate levels in the body.
Bacteria like Oxalobacter formigenes, Bifidobacterium spp., and Lactobacillus spp. aid in breaking down oxalates in the gastrointestinal tract. Without these helpful bacteria, the body may absorb more oxalates from the diet, increasing the risk of oxalate-related health problems, as per a review in Foods. Furthermore, the absence of Oxalobacter formigenes and other oxalate-degrading microbes may clarify why certain individuals appear more prone to oxalate-related issues than others.
Alongside aiding in the breakdown of oxalate in food, Oxalobacter formigenes might assist in the direct elimination of oxalate from the bloodstream. Studies on animals imply that oxalates can be transported from the blood to the intestines, where Oxalobacter formigenes break them down, potentially reducing the risk of oxalate buildup and related health problems.
Maintaining a healthy gut microbiome could be crucial in naturally lowering oxalate buildup in the body.
Gut microbiome. MP Art/Shutterstock
“We are losing microbes that possibly degrade oxalate,” stated Dr. Sabine Hazan, a gastroenterology specialist and CEO of Progenabiome. “The absence of microbes is the culprit of disease.”
The lack of Oxalobacter formigenes and other oxalate-degrading microbes may partially explain why certain individuals appear more susceptible to oxalate-related problems than others.
As per the review in Kidney Diseases from December 2023, “Our modern lifestyle induces the disappearance of beneficial microbacteria.” Antibiotics can diminish these beneficial bacteria. Independent of antibiotic exposure, western lifestyle reportedly lessens Oxalobacter formigenes colonization.
Health Conditions Linked to Oxalates
The adverse effects of oxalates have been documented since the 19th century. For instance, a toxicology study from 1823 published in the Edinburgh Medical and Surgical Journal recognized its toxic effects. In the late 1800s and early 1900s, physicians associated oxalates with a range of symptoms beyond kidney stones.
Contemporary research has tied oxalate overload to various health conditions:
- Cardiomyopathy: Crystal deposits can lead to arrhythmia, palpitations, syncope, dyspnea, and, in rare cases, chest pain.
- Chronic pain: Deposition in bones, nerves, and muscle cells can induce pain.
- Visual disturbances: Crystal deposits within the retina can result in vision issues like glaucoma, cataracts, retinal detachment, and visual abnormalities.
- Arthritis: Oxalate crystals in joints can cause pain and stiffness resembling arthritis, with hyperoxaluria sometimes leading to oxalate arthritis.
- Digestive issues: Oxalates can irritate the digestive tract lining, potentially contributing to problems like leaky gut syndrome.
- Autoimmunity: Oxalate crystals can incite inflammation, potentially contributing to autoimmune conditions.
Are Oxalates a Problem for You?
According to Masterjohn, some individuals possess a genetic mutation that heightens their inclination to produce oxalates, while others, without the mutation, may still be sensitive to oxalates.
Factors that might heighten susceptibility include:
- History of repeated antibiotic use or kidney stones
- Digestive issues such as Crohn’s disease or leaky gut syndrome
- Genetic predisposition to oxalate sensitivity
- Bariatric surgery
- Certain nutrient deficiencies, particularly vitamin B6
- Chronic yeast and fungal infections
- Diet high in oxalate-rich foods
Symptoms can be vague and overlap with many other conditions. Some signs that oxalates might be a problem include:
- Recurring kidney stones
- Unexplained joint pain or arthritis-like symptoms
- Chronic digestive problems
- Frequent urinary tract infections or bladder pain
- Chronic fatigue or brain fog
- Skin conditions like rashes or hives
- Symptoms worsening after consuming high-oxalate foods
“If you’re grappling with chronic health issues lacking a clear cause, it’s worth exploring whether oxalates could be playing a role,” stated Norton. For individuals affected by oxalate overload, “When oxalates leave the body, it’s conceivable to heal tissues and reverse chronic conditions.”
Identifying Oxalate Sensitivity
Although there isn’t a definitive test for oxalate sensitivity, several diagnostic methods can be beneficial:
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