There hasn’t been a ton of research specifically looking at vegans and kidney stone risk.
However, there is some, and I’ll sum it up here later in this post.
Ultimately, it shows that vegans may be at a bit higher risk for kidney stones, but most of the risk comes from other factors like genetics.
If you already have issues with kidney stones, see a doctor if you switch to a vegan diet just to stay on top of things and catch any issues early.
The 4 Main Types of Kidney Stones
Kidney stones are a lot like normal stones – solid masses – that come from the kidney.
There are 4 types of kidney stones that you should be aware of:
- Calcium oxalate stones – The most common type of stone, made from calcium and oxalate (both come from your diet).
- Struvite stones – Fast growing and large, and grow as a result of an infection (not related to diet).
- Uric acid stones – Typically formed because of dehydration, high protein diet, problems digesting purines, or genetic factors.
- Cystine stones – Not too common, mainly caused by genetics.
When it comes to a vegan diet compared to an omnivorous one, we’re only really worried about the first type of kidney stones – calcium oxalate stones.
Vegan Diets and Oxalate
Calcium oxalate kidney stones are formed when oxalate is absorbed into the bloodstream and excreted by the kidney.
But calcium from your diet can bind to oxalate before that point, which is why getting enough calcium in your diet is important.
That means there are 2 main concerns with this type of kidney stone:
- Getting too little calcium
- Eating too much oxalate
Every vegan diet is unique of course, but in general, vegan diets have more oxalate than omnivorous diets.
Oxalate is found in the highest amounts in certain plants, which may make up a large part of a vegan diet.
The 5 foods highest in oxalate are:
- Swiss chard
Here’s a more complete list of foods high in oxalate if you’d like more information.
If you don’t eat much of those foods, your risk of kidney stones is likely no higher than it was before going vegan.
But if you do, how much does your risk go up?
Let’s take a quick look at a few studies.
Studies on Vegan Diets and Kidney Stones
This first study didn’t look at diet type. Instead, it looks at how oxalate intake affects kidney stone risk.
The main finding was:
Spinach accounted for >40% of oxalate intake. For participants in the highest compared with lowest quintile of dietary oxalate, the relative risks for stones were 1.22 (95% confidence interval [CI] 1.03 to 1.45; P = 0.01 for trend) for men and 1.21 (95% CI 1.01 to 1.44; P = 0.05 for trend) for older women.
There was a statistically significant increase in kidney stone risk for both men and women who ate the most oxalate compared to those who had the least. However, it’s quite small – just about 20% higher.
Most people are somewhere in between the 2 extremes, and likely have a minimal, if any, increased risk of kidney stones.
In another study of data from EPIC-Oxford, researchers looked at the risk of kidney stones based on diet (vegans were grouped with vegetarians).
Vegetarians actually had a 31% lower risk when compared to meat-eaters.
That’s not a conclusive study, as it doesn’t factor in elements like lifestyle, but it does tell us overall that vegetarians don’t have anything major to worry about when it comes from kidney stones.
General Recommendations to Lower Risk of Kidney Stones
In general, there are 5 things you should do if you want to limit your risk of developing kidney stones as much as possible:
- Hydrate well
- Get enough calcium
- Reduce sodium
- Limit animal protein (vegans have this one down!)
- Avoid oxalate-rich foods
I bolded the 2 that might be affected by a vegan diet.
Getting calcium from sources like beans and seeds, which don’t have as much oxalate, takes care of both of these at the same time.
Here’s a full list of the best vegan sources of calcium if you’d like to take a closer look.
Summary: Kidney Stones and Vegans
It’s hard to conclude anything because the data is limited, but it looks like if anything, vegans may actually have a lower risk of kidney stones on average.
Perhaps if you’re eating 20 cups of spinach (that’s a lot of oxalate) a day, you’d have issues, but for the typical vegan, it doesn’t seem like there’s much to worry about.
Get enough calcium and stay hydrated, and your diet shouldn’t influence your risk much.
The bigger factors in your kidney stone risk are things like genetics and weight.