Oxalates The Poison You Didn't Know Much About

April 10, 2022

Oxalate, the Poison You Didn't Know Much About

Oxalic acid. Tiny little molecule we humans make as a byproduct of digesting glycine and hydroxyproline, two amino acids in protein. We have no use for it. It is an end-product of metabolism and just needs to be excreted. We get rid of about 10-30 mg a day. A few folks have a genetic problem with it and they have higher excretion rates (100-600 mg a day) and have many kidney stones, kidney failure. We call that systemic oxalosis. It's rare. The toxicologists say that 5 grams is a lethal dose and 500 mg per meter body surface area is dangerous. Ok, that means it is a bona fide poison too, at high levels.

But lots of plants use oxalate as part of their operating system. Like lectins, plants use oxalate to poison animals and insects so that they don't get eaten. In plants, the molecule is actually manufactured in the process of photosynthesis and is used in chelating many minerals to help maintain cellular levels in a constant range. Plants can grow in otherwise toxic soils with too much lead or cadmium around because oxalic acid binds up the minerals. Oxalic acid is useful to plants.

The problem is that we humans eat plants and don't think much about it. We just sort of assume it's safe for us to munch on. Hmmm. Did you know there have reported deaths from eating rhubarb leaves? Yup. Sad but true. How about kidney stones? Nine percent of Americans have them. 75% of kidney stones are oxalate in composition.

Then there are crystals of oxalate in our tissues if you go looking for them. For example, one autopsy study found that 79% of thyroid glands have oxalate crystals in them. The same study also found crystals in the thymus, blood vessel walls, kidneys, testicles, brain, eyes....it appears we deposit the crystals in an asymptomatic fashion and they accumulate over a lifetime. Could all those crystals be annoying our immune system sufficiently to set off an autoimmune response?

Is there any connection to disease? Well, yes. Kidney stones are common. But it is frequently taught that the mystery disease, vulvodynia in women, is best treated with a low oxalate diet.

It's not the disease state per se that is the problem, it is the low level of exposure that makes for long-term, chronic "annoyance" that just adds up. Could there be evidence for that? Bruce Ames, functional medicine pioneer extraordinaire, posited the "triage theory" that basically says we are limited by what's extreme at the moment, but maybe not be being just borderline deficient in the immediate sense, but accelerated in the chronic time-frame. The reverse of that is what is in action here. We are poisoned in the short term by what is extreme, but what is going on when we are chronically exposed to something noxious? Gundry has made a point of positing lectins as being the root of many autoimmune diseases. Could oxalates be another class of problem makers we haven't made widely known? We do know that low levels of many chemicals like PCBs, dioxins, DDT, etc play havoc with us. Those are man-made problems. But plants are also trying to avoid us. We are their "pests" and they make their own "pesticides" to keep us away. And just where do we get those oxalates (aka, "human pesticides") from? Heck, to be a real mid-Westerner, you have to have a rhubarb patch in back. And I do. Next week we'll talk more.

www.What will Work for me. Dr. Saladino in his book The Carnivore Code has written one of the best treatises on oxalates I have seen. He relates to his personal story of getting his own eczema exacerbated every time he ventures into eating some high oxalate foods. I'm trying a weight loss regimen based on his teaching and so far, I've got my glucose averaging below 90 most days by following his advice. I'm eating a lot of fatty animal products. And a lot of fish. I would love to find a simple measure of oxalate other than a 24-hour urine collection. But I now know that 30 mg should be our upper limit.

References: J Proteome Research, Prasad in Current Sci, Plant Physiology, JAMA, Eur J Clin Chem Clin Biochem, Am J Obstet Gyn, Lange - Poisoning, Bruce Aimes, Carnivore Code,

Pop Quiz

1. What are oxalates? Answer: a metabolic byproduct of digesting glycine and hydroxyproline, two amino acids.

2. How much do we naturally make?                           Answer: about 30 mg a day

3. Plants make oxalates for their own purposes. Examples?                             Answer: they use oxalates to inhibit them being eaten by poisoning caterpillars, as one example. And by binding heavy metals so that the plant can grow in otherwise heavy metal laden soils.

4. Human can get in trouble with oxalates. Can you name one example?                       Answer: Yes, you can drop dead from a salad of rhubarb leaves. Then there are kidney stones.  It goes on. 

5. Can you name the upper limit of safe oxalate?                             Answer: Cheap trick question. Bruce Aimes claims, in his triage theory, that low level of deficiency will manifest itself only when extreme and then changes your fate immediately, but at low levels may accelerate the process of aging. But the deficiency may be modulating your fate without your being aware. Reverse that and you have low level of toxicity modulating your fate, and you aren't aware. So, there may not be a "safe upper limit" by that metric.    Until now.

This column was written by Dr. John E Whitcomb, MD, Brookfield Longevity, 262-784-5300 or www.livelongmd.com.