What Are Oxalates?
Oxalates are organic acids (which means they are compounds that contain hydrogen and can lose a proton). They’re naturally found in some foods, and they are formed as byproducts of metabolic processes in the body, as well as byproducts of fungal metabolism.
Oxalates by themselves are generally quite insoluble, forming crystals which can deposit in tissues throughout the body, leading to a variety of problems (see below). Fortunately, our bodies have very effectively mechanisms for eliminating oxalates: first, few of the oxalates get absorbed from our food in the first place, as long as our guts are healthy and we’ve consumed plenty of calcium. Calcium oxalate remains in the stool in that case, gets excreted, and never causes a problem. If calcium is low in the diet, soluble oxalic acid will get absorbed into the bloodstream, but even then, if the amounts are low, it will get filtered out by the kidneys. If there’s a lot of oxalates, though, problems occur—not just in the kidneys (the most common kidney stones are calcium oxalate), but in other tissues as well.
Oxalate Excretion Gone Wrong
Oxalate levels in the bloodstream can increase if:
- You’re not consuming enough calcium. As mentioned above, typically very little of the oxalates in your food actually get absorbed, provided you’re getting enough calcium in your diet. If you are, then the excess combines with the oxalates and gets excreted in the stool. If you’re not, you end up with too many oxalates in the bloodstream.
- You have Leaky Gut Syndrome (or Increased Intestinal Permeability). The oxalates in your food shouldn’t get absorbed from the small intestine (unless they’re not complexed with calcium). But if the junctions of your small intestine aren’t as tight as they ought to be, all sorts of things end up in your bloodstream that shouldn’t be there, including insoluble oxalates. This gives them free access to roam throughout the body… and deposit anywhere they’d like.
- You have fungal overgrowth. This kind of goes hand-in-hand with Leaky Gut Syndrome, because gut inflammation tends to lead to fungal overgrowth, and fungal overgrowth tends to lead to Leaky Gut Syndrome. In addition to the problems that go along with increased intestinal permeability itself, though, oxalates are themselves byproducts of fungal metabolism. This means if you have yeast overgrowth, you automatically have more oxalates to deal with than just those consumed in the diet and produced by your own metabolism.
- You have gallbladder dysfunction (or you’ve had your gallbladder removed). The gallbladder’s job is to store bile, which is necessary for absorption of fat from your diet. Without adequate bile delivery, fats go undigested, and continue on through the digestive tract, getting excreted in the stool. The problem is, undigested fat tends to bind to calcium. So even if you have plenty of calcium that might have otherwise bound to excess oxalates and rendered them harmless, if you also have excess fat, the calcium isn’t available. Now oxalates—oxalic acid—instead gets absorbed into the bloodstream. (The other down side to this is that you end up with calcium deficiency too, which means bone loss.)
Symptoms of High Oxalates
Insoluble oxalate crystals can form in the bones, the joints, the lungs, the blood vessels, and the brain.
In the body, these crystals can cause pain, such as fibromyalgia and vulvodynia (vaginal pain).
In the bones, crystals can suppress bone marrow, leading to anemia and lower immune function. Iron may also complex with oxalates, which can deplete iron stores, also leading to anemia.
Excess oxalates from a fungal source can also bind to other positively charged minerals, leading to deficiencies in nutrients like calcium, magnesium, and zinc.
High oxalates will also deplete your sulfate stores… which carries its own set of problems.
Increased Toxicity, Leaky Gut Syndrome, and Hormone Depletion
Because of a reciprocal transporter in the gut, liver, and kidney called the Sat1 transport protein, we lose one sulfate molecule via feces or urine for every oxalate we reabsorb.
Low sulfate (sulfur) molecules are a big problem, for three main reasons:
- Sulfur is required for Phase II Detoxification in the liver. Three main Phase II Detoxification pathways require sulfur: sulfation, glucoronidation, and glutathione-S-transferase. Low sulfate will mean poor detoxification. If you remember that the primary philosophy of naturopathic medicine is giving your body the building blocks it needs to heal itself while removing the obstacles to cure, you can see why this is an issue: without toxin removal, the body’s ability to heal is severely compromised.
- Sulfates are required for production of gut mucus. The mucus in our guts keeps our microbiome healthy; without it, we are at risk for dysbiosis, and (again) increased intestinal permeability. Low sulfates have been linked in animal models to these as well as inflammatory bowel disease.
- Low sulfates lead to low hormone levels. Low sulfates are linked to low hormone levels, particularly cortisol and DHEA, although the same is true of sex hormones (progesterone, estrogen, and testosterone). The body uses sulfate to inactivate these hormones when they are not needed, like a switch. That way, it doesn’t have to create them from scratch every time. When there’s no sulfate to serve as the switch, the body has no choice but to spill the excess hormones into the urine—which means the next time they are required, it takes a lot more energy to produce them again.
Low Sulfates Make Methylation Problems Worse
Probably the best known genetic mutation is MTHFR, required for activating folate from the food for use in a biochemical process called the methylation cycle. This cycle is responsible for production of neurotransmitters such as serotonin and dopamine, for elimination of excess histamine, and for the recycling of sulfate molecules for reuse. When sulfate levels are low, the methylation cycle has to pick up the slack—which is an issue for people who have genetic mutations in these enzymes (MTHFR, MTRR, etc).
The strain can lead to a bottleneck of certain metabolites that can’t get “out the door,” as it were, including homocysteine (highly inflammatory, and associated with cardiovascular disease), and cysteine, a sulfur-containing amino acid. Cysteine is required for the body to form metallothionein, an antioxidant with a strong affinity for heavy metals. Without adequate metallothionein, the body is much more susceptible to heavy metals, especially in the brain.
Testing for High Oxalates
I usually choose to run an OAT (Urinary Organic Acid) test to check for oxalate levels, as this test also checks for yeast or fungal markers such as arabinose, potentially indicating the cause of the elevation of oxalates (or at least ruling out a few.) At the same time, the OAT test checks for nutrient deficiencies that may help to offset the problem (such as Vitamin B6, see below).
It is possible to run a 24-hour urine oxalate test through traditional labs, though.
Treatment of High Oxalates
If oxalate levels are high, before you set about looking for the root cause (which you should do, of course), you need to limit your intake and do what you can to bind the oxalates already present.
The foods to limit are mostly very healthy under other circumstances, and include:
- Veggies: certain greens (spinach, collard, chard, kale, or dandelion greens), beans, potatoes and sweet potatoes, certain squashes (summer, zucchini), beets, carrots, parsley, celery, eggplant, leeks, okra, olives, and peppers (chili and green)
- Fruits: blackberries, blueberries, raspberries, tangerines, kiwis, figs
- Proteins: anything soy, nuts and nut butters, sesame seeds and tahini
- Grains: wheat, buckwheat, amaranth
- Beverages: dark beer, black tea, instant coffee
- Other: chocolate, black pepper
Vitamin B6 helps to lower oxalate levels. This is because it is a cofactor for a liver enzyme (AGT) which converts the precursor for oxalates (glyoxylate) into the amino acid glycine, preventing it from turning into oxalates instead.
Calcium citrate binds to oxalate. Calcium, particularly given with food, helps to bind the oxalates in food, enabling their excretion in stool. Citrate also decreases oxalate absorption.
Healthy gut flora in the lactobacillus and bifidobacillus families have enzymes that break down oxalates in the intestines, so taking a comprehensive probiotic also helps.