Why Do Oxalates Cause Fatigue, Pain and Mineral Loss?

If oxalates make you tired, there’s a reason. Oxalate inhibits pyruvate kinase, the enzyme that catalyses the last step of glycolysis (sugar burning). That step converts phosphoenolpyruvate to pyruvate, and pyruvate is what feeds the Krebs cycle. Block it and glucose cannot finish the journey to ATP or energy production.

The pain, the mineral deficiencies and the crystal deposition are separate problems with separate mechanisms, and they do not all arrive together. Someone can have significant oxalate-driven fatigue with no kidney stones and no joint pain at all.

What ties the whole picture together is that oxalate is usually not the starting point. It is what accumulates when something upstream is not working — most often bile.

Signs and symptoms of high oxalate

Oxalate problems are hard to recognise because the symptoms are spread across systems that seem unrelated to each other. Commonly reported features include:

• Fatigue that does not match effort or sleep
• Joint aches and pains, often migratory, sometimes mistaken for early arthritis
• Vulvar pain, interstitial cystitis-type bladder pain
• Fibromyalgia-pattern muscle pain
• Eye pain or grittiness
• Poor sleep
• Headaches
• Bedwetting in children, urinary urgency or incontinence in adults
• Kidney stones (calcium oxalate)
• Grainy or sandy stools
• Mineral deficiencies that do not correct with supplementation
• Brain fog and word-finding difficulty

Oxalate crystals are not confined to the kidneys. Deposition has been documented in joints, blood vessels, bone, thyroid, retina, nerve tissue and heart, where the crystals cause local inflammation and mechanical irritation. In severe form this is called oxalosis, and it is well described in people with primary hyperoxaluria and kidney failure.

Why oxalates make you tired: the pyruvate kinase step

This is the mechanism that explains the fatigue.

Glycolysis breaks glucose down through ten steps. The final step is catalysed by pyruvate kinase (PK), which transfers a phosphate from phosphoenolpyruvate (PEP) to ADP, producing pyruvate and ATP. Pyruvate then enters the mitochondria and feeds the Krebs cycle, where the great majority of your ATP is actually made.

Oxalate inhibits pyruvate kinase because it is a structural mimic of enolpyruvate, the transition-state intermediate the enzyme forms during catalysis.¹ The enzyme binds oxalate as though it were part of the reaction and then cannot proceed.

The question that matters clinically is whether this happens at concentrations a person could plausibly reach. In isolated rat hepatocytes, oxalate inhibited glycolysis at the pyruvate kinase step — phosphoenolpyruvate rose, pyruvate and lactate production fell, and total glycolytic flux dropped. The apparent inhibition constant came out around 30–35 µM, which the authors noted is close to the physiological concentration of blood oxalate.²

That last detail is what lifts this out of test-tube territory. An inhibition constant far above anything achievable in a body is interesting. One sitting in the same range as normal blood levels means the enzyme is operating near its inhibition threshold under ordinary conditions, and a rising oxalate load pushes it over.

The consequence is a specific kind of tiredness. Glucose (sugar) is available, insulin is working, the mitochondria are structurally intact — and the substrate still is not arriving. People describe eating and not feeling any better for it, or feeling worse.

What I will not claim: in the same experiments, oxalate also reduced gluconeogenesis in cells from fasted animals, and blocking pyruvate kinase did not by itself increase glucose output.² So the tidy story that oxalate causes glucose to back up in the blood and feed yeast does not follow from the liver data. I have seen blood sugar instability travel with high oxalate clinically, but the mechanism for that link is not established and I am not going to present it as though it were.

Oxalate and D-lactate: a second route to brain fog

Lactobacilli in the gut produce D-lactate, the mirror-image isomer of the L-lactate human muscle makes when we do intense exercise. Humans clear D-lactate using a mitochondrial enzyme, D-lactate dehydrogenase (LDHD), which oxidises it back to pyruvate.³

Oxalate severely inhibits this enzyme. A 2024 study on the human protein tested both splice isoforms and found catalytic activity strongly suppressed by oxalate.⁴ When the same enzyme is disabled by mutation rather than by oxalate, the result is D-lactic acidosis.³ ⁴

D-lactic acidosis is a recognised human syndrome, and its presentation is neurological: confusion, slurred speech, unsteadiness, disorientation, brain fog. It is documented in short bowel syndrome and after bariatric surgery, where bacterial fermentation delivers more D-lactate than the body can clear.

So there are two independent routes from oxalate to feeling mentally flat — one through blocked ATP production, one through impaired clearance of a bacterial metabolite. They can operate in the same person, and they are made worse by the same things: more oxalate, and a gut producing more of what has to be cleared.

One correction to material circulating on this, including in an earlier version of this article: LDHD is a human mitochondrial enzyme, not a gut enzyme. Oxalate inhibiting it does not lower gut pH. It means D-lactate absorbed from the gut is not cleared once it reaches the body.

Where oxalates actually come from

Four sources, and they behave differently.

1. Diet

The high oxalate foods that matter most in practice are spinach, rhubarb, beetroot and beet greens, almonds and almond flour, cashews, sesame, buckwheat, sweet potato, chocolate, black tea, turmeric, star fruit and soy. Green smoothies are the quiet offender, because a blender lets someone consume several servings of raw spinach in one glass, which nobody would eat on a plate.

Cooking helps. Boiling leaches soluble oxalate into the water, which is then discarded — with reductions reported up to around 50% depending on the vegetable and method. In a food as high as spinach, half is still a great deal.

2. Your own metabolism

The liver makes oxalate as an end product of glyoxylate metabolism. Glyoxylate is normally converted to glycine by alanine-glyoxylate aminotransferase (AGT), which requires vitamin B6 (pyridoxine) as its cofactor. When that conversion is inefficient, glyoxylate is diverted to oxalate instead.

This is why B6 status matters so much here, and why oxalate can be high in someone eating almost no oxalate. It is also why the primary hyperoxalurias — inherited faults in these enzymes — produce catastrophic oxalate loads on any diet at all.

3. Vitamin C

Ascorbate is metabolised to oxalate. Whether supplementation raises urinary oxalate enough to matter has been argued for decades, partly because ascorbate also converts to oxalate inside the collection bottle, which confounded the older studies.

The most useful finding is about variation between people. In a controlled study, 1000 mg of ascorbic acid twice daily raised urinary oxalate and calcium oxalate crystallisation risk in roughly 40% of participants — and that responder group included both stone formers and non-stone formers.⁵

So the answer to “does vitamin C raise my oxalate” is that it does in some people and not others, and there is currently no way to predict which group someone is in except by measuring. A previous version of this article proposed that free copper was the determining factor. That was my speculation and I have removed it, because the data does not support it.

4. Fungal production

Covered in its own section below, because the evidence is more mixed than this space usually admits.

Bile is usually the upstream problem

This is the section that changes what people do, and it is the best-evidenced part of the whole topic.

Most dietary oxalate never reaches your bloodstream. In the gut, oxalate binds calcium to form calcium oxalate, which is insoluble and leaves in the stool. Calcium is the body’s intended oxalate binder, and it works well when the conditions are right.

Fat digestion is what determines whether those conditions hold.

The calcium soap problem

When fat is not absorbed properly, unabsorbed free fatty acids remain in the intestinal lumen. Fatty acids bind calcium, forming insoluble compounds called calcium soaps — the same chemistry as ordinary soap, which is a fatty acid salt.

Calcium bound up in soaps is not available to bind oxalate. So the oxalate that would have left in the stool stays soluble and gets absorbed instead.⁶ ⁷

There is a second mechanism operating alongside it, and it is the one most missed. Unabsorbed bile acids and fatty acids reaching the colon increase the permeability of the colonic mucosa to oxalate directly.⁷ ⁸ So fat malabsorption raises oxalate absorption twice over: more free oxalate available, and a more permeable surface for it to cross.

This has a formal name — enteric hyperoxaluria — and it is well characterised in people with Crohn’s disease, coeliac disease, chronic pancreatitis, short bowel syndrome, and after bariatric surgery or ileal resection.⁶ ⁷ ⁸ It is also documented with orlistat, a lipase inhibitor taken for weight loss, which produces fat malabsorption deliberately.⁹

What the research literature describes in surgical patients, I see clinically in people whose fat digestion is impaired for less dramatic reasons: sluggish bile, thick bile, a removed gallbladder, low bile salt production. The mechanism does not require surgery. It requires fat arriving in the colon.

Bile salt production connects back to methylation and transsulfuration, since taurine, choline and phosphatidylcholine are all needed for bile composition. And low bile means constipation, which lengthens transit time and gives the gut environment more opportunity to shift. It is a loop rather than a line.

Why spinach is not the calcium food it appears to be

Spinach is routinely listed as a high-calcium vegetable. On paper that is correct: it contains a substantial amount of calcium per serving. In practice it is close to useless as a calcium source, and the reason is oxalate.

The calcium in spinach is already bound to oxalate inside the plant, as calcium oxalate crystals. It arrives pre-complexed and does not readily dissociate. When calcium absorption from spinach was measured directly against milk in the same people, using a double-isotope method, milk delivered 27.6% absorption and spinach delivered 5.1%.¹⁰

Compare that to kale, a low-oxalate green, where fractional calcium absorption came out at 40.9% against 32.1% for milk in the same study design — better than dairy.¹¹

Two things follow from this, and they point in opposite directions to what most people assume.

First, a diet built on spinach and other high-oxalate greens can look calcium-adequate on a nutrition tracker while delivering very little. Someone can be simultaneously eating “plenty of calcium” and absorbing almost none of it.

Second, and more useful: because calcium is the binder, eating high-oxalate foods with a separate calcium source reduces how much oxalate you absorb. The calcium has to come from a different food, so that it is free in the gut rather than already complexed. That is why increasing dietary calcium is the standard, evidence-supported approach to reducing oxalate absorption, and why cutting out dairy while continuing green smoothies is close to the worst possible combination.

Yeast, mould and oxalate: what the association does and does not prove

(Mould and mold are the same word, spelled differently either side of the Atlantic. Both appear in the literature.)

High oxalate and high fungal markers turn up together on organic acid testing often enough that the connection is treated as settled in this field. I want to separate what is established from what is inferred, because the two get merged and the distinction changes how you act on it.

What is established. Fungi are prolific producers of oxalic acid — it is one of the most commonly secreted organic acids across the fungal kingdom. Aspergillus niger in particular produces it via oxaloacetate acetylhydrolase, and calcium oxalate crystal deposition around the fungus is a recognised histological finding in human aspergillosis, including in lung tissue.¹² The organism uses oxalic acid to manipulate local pH and chelate calcium in its environment.

What is not established. That gut yeast colonisation raises oxalate in a living person. As of 2025, a link between fungal oxalic acid production and pathogenicity has not been demonstrated for any human fungal pathogen.¹² There are in vitro reports of yeast producing oxalic acid in culture media, and yeast has been recovered from bladder stones, but nobody has shown that treating gut yeast lowers urinary oxalate, or that colonisation raises it in the first place.

It is also worth knowing that some commensal fungi degrade oxalate rather than producing it, which complicates the picture further.

What I take from this clinically. The association on an OAT is what I’ve seen and worth acting on. Poor bile and fat malabsorption produce both a gut environment favourable to yeast and increased oxalate absorption, so a shared upstream cause is at least as plausible as yeast making the oxalate. I treat high oxalate with high fungal markers as a signal to look at bile, fat digestion and transit time — not as proof that the yeast is manufacturing the oxalate.

If the elevations are proportional to each other, the fungal explanation is more credible. If oxalate is high and fungal markers are only mildly raised, something else is driving it.

Oxalate strips minerals

Oxalate in its dibasic anion form binds positively charged minerals with high affinity: calcium, magnesium, zinc, iron. Bound in the intestine, those minerals leave in the stool rather than being absorbed.

This produces a specific and recognisable pattern — mineral deficiencies that do not correct with supplementation, because the supplement is being bound on the way through. Magnesium and zinc are the ones that show it most clearly.

The consequences follow the minerals. Low zinc affects the zinc-copper balance and progesterone production. Low magnesium and B6 compound both the oxalate problem and the mineral problem, since B6 is what keeps glyoxylate heading toward glycine rather than oxalate. Every one of those deficiencies makes the next round worse.

Oxalate as a metal chelator

The same binding chemistry applies to toxic metals. Oxalate-metal salts differ enormously in solubility, expressed as the solubility product (Ksp) — a measure of how readily the complex dissociates.

Mercury oxalate is orders of magnitude less soluble than calcium oxalate, which means once formed it is far more likely to stay put in tissue rather than dissociate and be excreted. This is worth thinking about around dental amalgam removal and during any active metal mobilisation, where you are increasing circulating metal at the same time as oxalate is available to complex with it.

It is also a reasonable argument for not putting high-oxalate foods and higher-risk metal foods in the same meal — spinach with fish being the obvious example.

The gut bacteria that eat oxalate

Some gut organisms degrade oxalate before it can be absorbed. Oxalobacter formigenes is the specialist: it uses oxalate as its sole source of carbon and energy, so it has no reason to exist anywhere else in your body.

The evidence here improved considerably in 2025. In a proof-of-concept study, all 22 healthy adults were successfully colonised after a single dose, ten remained colonised for at least a year, and urinary oxalate fell.¹³ Nine of the eleven participants who lost colonisation reported antibiotic use.¹³

That antibiotic finding is the practical one, and there is published detail on which drugs matter. Testing four human strains found all of them resistant to amoxicillin, amoxicillin/clavulanate, ceftriaxone, cephalexin and vancomycin — and all of them sensitive to azithromycin, ciprofloxacin, clarithromycin, clindamycin, doxycycline, gentamicin, levofloxacin, metronidazole and tetracycline.¹⁴

That list explains a great deal of clinical history. Someone with recurrent oxalate problems and years of doxycycline for acne, or repeated metronidazole for gut infections, has a plausible mechanism sitting in their notes. It also means the standard functional-medicine yeast protocol, which frequently includes some of these agents, may be removing the organism that was protecting them.

Other species contribute to oxalate degradation as part of a broader diet — various Lactobacillus and Bifidobacterium strains among them — though none depend on it the way Oxalobacter does, and commercial probiotics have not yet been shown to reduce urinary oxalate reliably.

Oxalate dumping: what I have observed and what has been demonstrated

I want to be clear about this one.

What I see clinically. People who cut oxalate abruptly, particularly those with a high baseline intake, frequently feel worse before they feel better. The pattern is consistent enough that I plan for it: grainy or sandy stools, burning with urination, joint pain flaring, irritability, rashes, toilet-training regression in children, and yeast symptoms flaring. It usually settles, and it can recur intermittently over months. This is clinical observation across a lot of cases, and I would not have a reason to describe it if it were not happening, but it’s not that common. Maybe 10% of the people I see with oxalate issues.

What has been demonstrated. No study has documented mobilisation of tissue oxalate triggered by dietary reduction in people with normal kidney function. That trial has not been done.

What has been demonstrated in a related setting. Tissue oxalate mobilisation is thoroughly established where the tissue burden is extreme. In primary hyperoxaluria patients receiving liver-kidney or kidney transplants, hyperoxaluria persisted in most patients for up to three years afterwards, with the first year being the most marked, specifically attributed to mobilisation of calcium oxalate stores laid down during kidney failure.¹⁵

So stored oxalate coming back out of tissue is documented, in a population where the trigger is restored kidney function rather than a dietary change. Whether the same mobilisation happens on a smaller scale in an ordinary person cutting spinach is an open question that nobody has tested.

My practical position: I reduce oxalate gradually rather than abruptly, typically over weeks rather than days, because the cost of going slowly is nothing and the cost of going fast is a person who feels terrible and abandons the process. The commonly quoted figure of 5–10% per week is practice convention rather than a researched number. Adequate hydration, calcium taken with meals, and attention to bile and fat digestion throughout matter more than the exact rate.

Oxalate, mitochondria and free radicals

Oxalate exposure generates reactive oxygen species and causes mitochondrial dysfunction. This is well demonstrated — but the evidence needs its label, because it is routinely quoted more broadly than it supports.

Almost all of this work is in renal tubular epithelial cells, in vitro, and in hyperoxaluric rats. In those models, mitochondria are described as the primary source of ROS in oxalate toxicity, with NADPH oxidase as a second major source, and the combination produces membrane injury and cell death.¹⁶

What that supports is a claim about kidney tissue exposed to high oxalate. It does not, on its own, support the broader claim that circulating oxalate damages mitochondria throughout the body. The pyruvate kinase mechanism above is a better-founded route from oxalate to a systemic energy problem, because it is a direct enzymatic effect at concentrations that occur in blood.

The autism findings, with their limits stated

One study is cited constantly in this space and deserves to be described accurately.

Konstantynowicz and colleagues compared 36 children and adolescents with autism spectrum disorders against 60 matched controls, and found approximately three-fold higher plasma oxalate and 2.5-fold higher urinary oxalate in the ASD group.¹⁷ The authors were explicit that they could not say whether this reflected impaired renal excretion, increased intestinal absorption, or something else, and whether oxalate crosses the blood-brain barrier in these children was unresolved.¹⁷

The limits worth stating: it is a single cross-sectional study with modest numbers, it has not been replicated at scale, and despite the significant hyperoxaluria the researchers found no evidence of kidney stone disease or lithogenic risk in these children.¹⁷ One of the co-authors is a long-standing advocate of low-oxalate dietary approaches, which does not invalidate the work but is relevant context.

Testing

Urinary oxalate on an organic acid test is what most people use, and it measures oxalic acid alongside its precursors glyceric and glycolic acid. That combination is more informative than oxalate alone, because the precursor pattern gives some indication of whether the load is dietary, endogenous, or a specific enzyme problem.

The limitation to hold onto: urinary oxalate tells you what is leaving. It does not tell you what is stored, and it does not tell you what is happening inside cells. A person actively depositing oxalate in tissue and a person clearing it well can produce results that look similar for opposite reasons.

This is the same point I make about every marker. A number means nothing without the context around it. High urinary oxalate in someone with excellent bile function who has been eating almond flour daily is a dietary story with an obvious fix. The same number in someone with a removed gallbladder, poor fat digestion and years of antibiotics is a different problem entirely, and taking away their spinach will not touch it.

What actually helps

Direction rather than protocol, since the answer depends entirely on which part is driving it:

• Investigate fat digestion and bile function first. This sits upstream of most of the rest.
• Take calcium with meals containing oxalate rather than removing calcium from the diet.
• Reduce dietary oxalate gradually if reducing it at all, and treat it as a time-limited trial rather than a permanent diet.
• Check B6 status, since it determines whether glyoxylate becomes glycine or oxalate.
• Check magnesium and zinc, and expect them to be harder to correct while oxalate load is high.
• Consider antibiotic history as a contributor to oxalate-degrading capacity.
• Investigate oxalate alongside sulfate depletion rather than separately. The two share a kidney transporter and travel together for that reason, which is also why phenol and salicylate sensitivity so often turns up in the same person.
• Maintain hydration throughout, particularly during any reduction. Citrate in the urine inhibits calcium oxalate crystal formation, which is why hydration and citrate status are handled together in stone prevention.

In summary

Oxalate causes fatigue by blocking the last step of glycolysis, at concentrations close to what circulates normally. It causes mineral deficiency by binding minerals before they can be absorbed. It causes pain through crystal deposition in tissue.

But it usually accumulates because something else went wrong first. Fat is not being digested, bile is not flowing, calcium is bound up in soaps instead of binding oxalate, and the organisms that degrade oxalate have been removed by antibiotics.

Which is why the question worth asking is not how to remove more oxalate from the plate, but why so much of it is getting through.

Frequently asked questions

What are the symptoms of high oxalate?
Fatigue disproportionate to activity, joint and muscle pain, vulvar or bladder pain, eye grittiness, grainy stools, mineral deficiencies that resist supplementation, and in children bedwetting or toilet-training regression. Kidney stones are the best-known consequence but many people with high oxalate never form one.

Why do oxalates make you tired?
Oxalate inhibits pyruvate kinase, the enzyme catalysing the final step of glycolysis, at concentrations close to normal blood oxalate.¹ ² Glucose cannot complete its conversion to pyruvate and therefore cannot feed the Krebs cycle efficiently. The fatigue is a substrate delivery problem rather than a mitochondrial structural one.

Does Candida or yeast produce oxalate?
Fungi as a group secrete oxalic acid readily, and Aspergillus niger does so definitively — calcium oxalate deposition is a recognised finding in human aspergillosis.¹² Whether gut yeast colonisation raises oxalate in a person has not been demonstrated, and no link between fungal oxalic acid production and pathogenicity has been established in any human fungal infection.¹² The association on testing is real; the causal direction is not settled.

Is oxalate dumping real?
Tissue oxalate mobilisation is documented in primary hyperoxaluria patients after transplant, where hyperoxaluria persisted for up to three years as tissue stores released.¹⁵ Whether the same thing happens on a smaller scale when someone with normal kidneys cuts dietary oxalate has never been studied. I see the symptom pattern regularly in practice and plan for it, but I am describing clinical observation rather than published evidence.

How fast should I reduce oxalate in my diet?
Gradually, over weeks rather than days. The frequently quoted 5–10% per week is practice convention rather than a researched figure. Going slowly costs nothing; going fast risks a reaction severe enough that people abandon the process entirely.

Does spinach really contain a lot of calcium?
It contains calcium but you cannot absorb it. The calcium in spinach is already bound to oxalate inside the plant as calcium oxalate crystals, which do not readily dissociate. Measured directly against milk in the same people, spinach delivered 5.1% fractional calcium absorption against 27.6% from milk.¹⁰ Kale, which is low in oxalate, came out at 40.9% — better than dairy.¹¹

Should I stop eating calcium if I have high oxalate?
No, and this is the most common mistake in this area. Calcium is what binds oxalate in the gut and carries it out in the stool. Removing it increases how much oxalate you absorb. Calcium taken with oxalate-containing meals, from a food or supplement separate to the oxalate source, reduces absorption.

Does vitamin C cause oxalate problems?
In some people. When 1000 mg was given twice daily under controlled conditions, urinary oxalate and calcium oxalate crystallisation risk increased in about 40% of participants, including people with no history of stones.⁵ The other 60% showed no meaningful change. There is no way to predict which group you are in without measuring.

Can antibiotics cause high oxalate?
Plausibly, by eliminating Oxalobacter formigenes, which depends entirely on oxalate for energy. Human strains are sensitive to azithromycin, ciprofloxacin, clarithromycin, clindamycin, doxycycline, gentamicin, levofloxacin, metronidazole and tetracycline, while being resistant to amoxicillin, amoxicillin/clavulanate, ceftriaxone, cephalexin and vancomycin.¹⁴ In a colonisation study, nine of eleven people who lost colonisation reported antibiotic use.¹³

Does polyethylene glycol (PEG) raise oxalate?
This comes up in relation to colonoscopy preparation. The chemistry exists in principle: bacteria can break polyethylene glycol down stepwise toward ethylene glycol, and ethylene glycol is metabolised through glycolaldehyde and glycolate to glyoxylate and then oxalate. No human study has shown that PEG laxatives raise urinary oxalate, and the large PEG polymers used in bowel preparation are largely neither absorbed nor fermented. So it is a mechanistically plausible route with no human data behind it, which is a different position from either “yes” or “no”.

Can high oxalate cause brain fog?
Two mechanisms could contribute. Inhibited pyruvate kinase limits ATP production in a brain that is metabolically expensive.¹ ² And oxalate inhibits human D-lactate dehydrogenase, the enzyme that clears bacterially produced D-lactate — and failure of that enzyme causes D-lactic acidosis, which presents neurologically with confusion and disorientation.³ ⁴

Do carnivore and ketogenic diets cause oxalate dumping?
Both remove nearly all dietary oxalate at once, which is why reports of dumping-type symptoms cluster around them. Two things are worth knowing. The pattern people describe on starting these diets is the same pattern I see with any abrupt reduction, and gradual withdrawal is available to them too. And a very high protein intake gives the liver more substrate for endogenous oxalate production, so removing dietary oxalate entirely does not necessarily mean total oxalate load falls as much as expected.

Is a low oxalate diet something I stay on permanently?
It should not be. High-oxalate foods include a large share of the vegetables, nuts and seeds worth eating, and long-term restriction narrows the diet considerably while doing nothing about why oxalate was accumulating. Treat it as diagnostic and time-limited, and work on bile, fat digestion and mineral status during that window.

References

1. Reed GH, Morgan SD. Kinetic and magnetic resonance studies of the interaction of oxalate with pyruvate kinase. Biochemistry. 1974;13(17):3537-41. (In vitro enzyme kinetics; oxalate as transition-state analogue.)
2. Buc HA, Demaugre F, Moncion A, Leroux JP. Metabolic consequences of pyruvate kinase inhibition by oxalate in intact rat hepatocytes. Biochimie. 1981;63(7):595-602. PMID 7284471. (Animal model; isolated hepatocytes. Apparent Ki approximately 30-35 µM.)
3. Jin S, Chen X, Yang J, Ding J. Lactate dehydrogenase D is a general dehydrogenase for D-2-hydroxyacids and is associated with D-lactic acidosis. Nature Communications. 2023;14:6638. (Structural and biochemical study; mouse enzyme.)
4. The catalytic action of human d-lactate dehydrogenase is severely inhibited by oxalate and is impaired by mutations triggering d-lactate acidosis. Archives of Biochemistry and Biophysics. 2024. PMID 38373542. (In vitro; recombinant human enzyme, both isoforms.)
5. Massey LK, Liebman M, Kynast-Gales SA. Ascorbate increases human oxaluria and kidney stone risk. Journal of Nutrition. 2005;135(7):1673-7. (Human study; responder subgroup approximately 40%.)
6. The management of patients with enteric hyperoxaluria. Urolithiasis. 2016;44(1):45-51. PMID 26645872. (Review; human.)
7. Hyperoxaluria: a gut-kidney axis? Kidney International. 2011. (Review; two mechanisms of fat malabsorption hyperoxaluria.)
8. Intestinal oxalate absorption, enteric hyperoxaluria and risk of urinary stone formation in patients with Crohn’s disease. (Human study; controlled standardised conditions.)
9. Fat malabsorption induced by gastrointestinal lipase inhibitor leads to an increase in urinary oxalate excretion. Kidney International. 2004;65(4). (Animal model; orlistat in rats.)
10. Heaney RP, Weaver CM, Recker RR. Calcium absorbability from spinach. American Journal of Clinical Nutrition. 1988;47(4):707-9. PMID 3354496. (Human study; n=13, double-isotope crossover.)
11. Heaney RP, Weaver CM. Calcium absorption from kale. American Journal of Clinical Nutrition. 1990;51(4):656-7. (Human study.)
12. Fighting Aspergillus infection using biocontrol bacteria: a proof-of-concept of environmental interference in a translational setting. 2025. (Preprint; states that a link between oxalic acid production and pathogenicity has not been demonstrated in any human fungal pathogen.)
13. Inducing Oxalobacter formigenes colonization reduces urinary oxalate in healthy adults. Kidney International Reports. 2025. (Human study; n=22, proof of concept.)
14. Sensitivity of human strains of Oxalobacter formigenes to commonly prescribed antibiotics. Urology. 2012;79(6):1286-9. PMID 22656407. (In vitro; four human strains.)
15. Bergstralh EJ, Monico CG, Lieske JC, et al. Transplantation outcomes in primary hyperoxaluria. American Journal of Transplantation. 2010;10(11):2493-2501. (Human; tissue oxalate mobilisation post-transplant.)
16. Joshi S, Peck AB, Khan SR. NADPH oxidase as a therapeutic target for oxalate induced injury in kidneys. Oxidative Medicine and Cellular Longevity. 2013;2013:462361. (Review; renal cells in vitro and hyperoxaluric rats.)
17. Konstantynowicz J, Porowski T, Zoch-Zwierz W, et al. A potential pathogenic role of oxalate in autism. European Journal of Paediatric Neurology. 2012;16(5):485-91. PMID 21911305. (Human; cross-sectional, n=36 vs 60 controls.)