Why do some people seem to tolerate oxalate in their diets?

This is perhaps one of the toughest questions that I get. It actually requires a bit of discussion to get to my answer. I’d like to start by considering a thought experiment.

My father was born in Switzerland; he emigrated to Canada back in the 50’s. His mother was born in Switzerland in 1909. She died in 2003 at 94. That’s a good, long life.

She had also smoked until she was 89; she started to smoke in her teens.

Did she die of smoking related disease? No! My grandmother had been living on her own (my grandfather having passed in his 70’s), enjoying the companionship of her pets for many years. In fact, her death is linked to a a completely unexpected fall, when she was chasing her dog after he had managed to get away from her. The resulting brain injury from her fall left her unable to live on her own; a few years later, after being in an elder residence, she passed away. She had given up smoking after her injury (somewhat unintentionally), never to take it up again because of her living situation.

But that can’t be right? She smoked for more than 70 years, and she didn’t die of cancer? She never got COPD?

It’s true. She never had any lung related ailment, and was unusually fit and spry for her age as long as I knew her. Yet she smoked for the vast majority of her adult life.

So we should all be able to smoke, right? That’s really the argument when it comes to oxalate: other people can eat it in quantity, so it should be okay for me too. But is that how it works?

Here’s where the concept of “outliers” comes in. Everyone knows an outlier in one area or another – someone who eats junk food all day long and stays slim; someone who never exercises, but can go out on a weekend and beat their friends at the sport of their choosing; someone who smoked for a lifetime and never died of cancer (like my grandmother). This doesn’t mean this is “good advice” or even that it’s how everyone “should” be; it just means some people seem to have either the genetics or metabolic wellness or luck – and problematic behaviours don’t seem to affect them in the way you would expect.

This is why we talk about smoking (and many other behaviours) in terms of increased risk. We can’t guarantee that you’ll get sick if you smoke, but what we can say is that you have an increased risk of getting sick if you do. As a result, we have decided as a society to encourage people to avoid it.

With that said, here’s my position on oxalate and whether you should be able to “tolerate” it: oxalate is a human poison in sufficient dose, and it has its own entry (with an associated research study) in the FDA Poisonous Plant database. Animal poisonings are fairly common with oxalate, which is available in toxic amounts in common dieffenbachia. Cases of human poisoning due to consuming foods high in oxalate have been reported by the Centre for Food Safety in Hong Kong.

It’s also possible to harm yourself (and affect kidney function) with something like rhubarb, which is a commonly consumed food. Obviously, you would have to consume a lot of anything that we consider a “safe” human food in order to truly poison ourselves, but what is happening to us when we eat below this threshold of intake? The truth is: we don’t know for sure.

Which brings me back to the original question, which is why do some people seem to do okay with oxalates? After all, if oxalate is actually poisonous (in big enough amounts), wouldn’t everyone suffer with it?

The short answer is that we don’t know for a number of reasons:

  1. We do seem to handle oxalate without issue below certain thresholds. So an intake of 40-60 mg per day (which is defined as a low oxalate diet) seems to allow us to excrete it effectively. Once out of our bodies, it can’t accumulate, but the trick is to get it out relatively quickly. Our kidneys do the lion’s share of this work, although oxalate can be excreted in other ways as well;
  2. Oxalate issues are only understood in the context of kidney stones. So our body of knowledge on oxalate is biased to how to reduce kidney stones and not why someone is absorbing oxalate in the first place. As a result, we don’t really know if there are factors that affect why we might absorb oxalate more readily, nor why we might be less effective at excreting it – both of which would be significant factors in how well we tolerate our dietary oxalate intake; and,
  3. Because our research on oxalate is significantly biased to the issue of kidney stones, no one even looks for oxalate affecting our health if we don’t already have kidney stones. The only time we look for oxalate in the rest of the body is when a patient is in kidney failure! So there is the further issue that people could have oxalate affecting their health, but no one is looking for it.

    A great example of not seeing what we aren’t looking for can be found in the research that shows you can predict someone’s age by the amount of oxalate found in their thyroid. As you get older, you have more oxalate in the thyroid tissues. So that means we are accumulating it over time. Could oxalate actually be part of the reason that we have more inflammatory disease as we age? Oxalate is known to be inflammatory, but no one is looking at that possibility.

So here’s the thing: oxalate may not be affecting some people, but perhaps that’s not where our focus should be. Perhaps the question to ask is if oxalate could be affecting me, how would I know? I’d suggest that if you are working very hard to eat a “healthy” diet, but aren’t feeling your best, then take a look at what you are eating. Do you have a lot of high oxalate foods that you are consuming regularly? Are you a fan of plant-based superfoods? Has your health or energy actually dropped after changes to make your diet more healthy? Do you have inflammation? Do you have a diagnosis of an inflammatory condition? If you answered yes to any 2 of these, you may not be handling oxalate as well as you might think!

If you are suspicious that you might have an issue with oxalate, please contact me. I can help! You can request an appointment here.