If I had to give you a yes or no answer, I’d say that no, vegan protein powder does not cause kidney stones, especially for most vegan powders.
But the whole kidney stone issue is pretty complicated.
To be as brief as possible, I’ve only focused on the parts potentially related to vegan protein powders. So there’s a lot glossed over out of necessity.
If you’re interested in this topic because of serious kidney stone issues that you’ve had in the past, be smart and talk about this with a doctor. I’m not a medical professional, just a guy that enjoys doing research and tries to break it down as simply as possible.
Table of Contents
Kidney Stones 101: The 4 Main Types
A kidney stone is a solid mass that can be excreted from the kidney – that’s not supposed to happen. It typically means that there’s insufficient liquid, or that your body isn’t using the solids as it’s supposed to (think absorbing minerals like calcium).
But the stone itself can be made of a variety of material, and in different combinations.
In general, there are 4 main types of kidney stones:
- Calcium stones – This is the most common form by far. They are usually comprised of calcium and oxalate (more on this later).
- Struvite stones – These grow fast and large, and are created as a result of an infection.
- Uric acid stones – Usually formed as a result of the purines in a high protein diet, or dehydration. Can also be affected by genetic factors.
- Cystine stones – Caused by genetic disorders, but not very common.
When it comes to vegan protein powder and kidney stones, we care most about calcium stones (specifically calcium-oxalate stones), and uric acid stones.
What Causes Kidney Stones?
Across the different types of kidney stones, there are several different causes, including (1):
- Other medical conditions
We’re only interested in 1 here – dietary.
Then we can break it down further, because there are 6 main aspects of the diet that can affect kidney stone formation:
- Protein intake
- Oxalate intake
- Extreme diets
When we think about protein powder, most of those don’t apply. Hydration, calcium, sodium, and extreme dieting are all separate aspects.
Kidney stones can be caused my many lifestyle factors – diet is only one. Protein powder can only potentially affect protein intake and oxalate intake.
How Does Protein Intake Affect Kidney Stone Formation?
What we do know is that high protein diets increase the risk of kidney stones.
Research has shown that putting subjects on a low carbohydrate, high protein diet (mostly animal protein), increases the risk of kidney stones significantly (2).
Many similar studies have been done, that show similar results. Subjects (usually inactive) typically increase their protein intake about 100% (e.g. from 90 to 180 grams per day) while reducing carbohydrate intake. It doesn’t necessarily apply to athletes, but it is a concern.
The question is why does a high protein diet cause an increased risk of kidney stones?
The research points towards acid-base load (3).
In most cases, animal proteins are composed of amino acids that are later broken down into acids, while plant proteins are broken down into bases (the opposite of acidic).
We know that uric acid kidney stones need a high uric acid concentration, along with acidic urine in order to form (4).
Not only are acidic conditions a common kidney stone formation requirement, but a high acid load is difficult for kidney’s to handle, which could impede their functionality.
Protein intake can increase the risk of kidney stones, but only if fairly high. It’s also typically only studied in untrained populations who are told not to be active during the study.
Are You Saying That Animal Protein Causes Kidney Stones?
“But I’ve eaten animal proteins all my life and never got kidney stones.”
You might be saying something like that.
Keep in mind that the issues only appear in high protein diets. At low-medium amounts of protein, the science shows that there is no significant risk difference between plant and animal protein sources (5).
Unless you’re eating a ton of protein over a long period of time, most people will never have an issue.
The type of protein (animal vs plant) only matters once you’re consuming a very high amount of protein. Even then, individuals may respond differently.
Can Drinking Too Many Protein Shakes Cause Kidney Stones?
If you’re consuming an extremely high amount of protein, you could still be at risk of kidney stones (the science isn’t clear when it comes to plant proteins here). However, you’re likely at a lower risk than if you were supplementing whey protein.
If you’re eating a reasonable amount of protein either way, you won’t have an increased risk of kidney stone formation.
Unless you’re drinking several protein shakes a day, I think it’s fair to say that vegan protein powders won’t cause kidney stones based on protein intake alone.
How Does Oxalate Intake Affect Kidney Stones?
Oxalate is found in a lot of different foods.
It’s also found in calcium-oxalate kidney stones. If there is too much oxalate in a kidney, along with other conditions (like low amounts of liquid), it can form stones with calcium.
Oxalate can also interfere with the absorption of calcium (6).
This is the big reason that people are often skeptical of vegan protein powders.
Why? Because certain plant foods are really high in oxalate. Spinach, beets, and sweet potatoes to name a few.
Some plant foods are high in oxalate, and we know that oxalate is a main part of certain kidney stones. It’s reasonable to be at least have questions about this.
Is Oxalate Consumption A Major Concern For Vegans?
A study from the Harvard School of Public Health found that people who ate plant based diets actually had a lower chance of kidney stone formation than others (9).
The research generally shows that unless your total oxalate intake is greater than 300mg, and you have a reasonable calcium intake, you’re not at a higher risk of kidney stone formation. That being said, doctors typically recommend that those with a history of kidney stones aim for a lower amount (usually 50 to 100mg).
Either way, you’re probably not getting that from vegan protein powder alone, as long as you’re not having several (literally) servings per day.
Oxalate Content in Vegan Protein Powder
The next question for us is what’s vegan protein mostly made of?
- For the most part peas (pea protein), which has a relatively low oxalate content.
- Brown rice protein is common has a low-moderate amount of oxalate.
- Hemp is actually reasonably high in oxalate (7).
- Soy is high in oxalate, but isn’t found in many vegan protein powders (a common misconception) (8).
So we have a bit of a mix. There’s definitely a significant amount of oxalate in most plant-based protein powders, but it’s rarely super high.
A typical serving size (one scoop) is around 30 grams. Even if it consisted of pure hemp protein, that would only be about 22mg of oxalate. This is assuming the oxalate content of hemp protein is similar to the oxalate content of hemp seeds (73.6 mg/100g).
Realistically, it’s much lower, since pea protein has even less oxalate in it, and is the main component in almost all vegan protein powders.
Based on that, I feel it’s reasonable to conclude that if your oxalate consumption is causing you health problems (which is really could), it’s not from the amount in a protein shake or two a day. If you’d like to see the oxalate content of more foods, here are 2 good guides:
Oxalate and veganism is a complicated subject, and way outside the scope of this post. If you’re interested in more, this is a pretty well written and cited guide.
Most vegan protein powder is relatively low in oxalate.
Conclusion: Vegan Protein Powder Likely Doesn’t Affect Kidney Stone Risk
Let me try to sum up what we went over, because it was a lot:
- Of all the many potential causes of kidney stones, vegan protein powder can really only be involved in 2 of them: protein consumption, and oxalate consumption.
- High protein intake (really high) can cause kidney stones, whether it’s animal protein or plant protein. But the research shows that your risk is less when it comes to plant proteins.
- Vegan protein powder is relatively low in oxalate content, so that’s not a concern either.
Bottom line: If you’re eating a reasonable amount of protein, having a portion of that come from vegan protein shakes won’t significantly increase your risk of kidney stone formation.
In fact, evidence seems to suggest that vegans in general have lower risk of kidney stones if anything.
Again, I’m not a medical professional of any kind, just a vegan who likes to research topics like this. If you’ve had real kidney stone issues in the past and are apprehensive about using vegan protein powder, talk to an actual doctor.
If you’re interested in finding a good vegan protein powder at this point, take a look at our guide to the top plant-based protein powders.