How does a ketogenic diet affect kidney stones?

By Dr. Stephen Phinney and the Virta Team

Our clinical experience is that kidney stones are rare during a well-formulated ketogenic diet.

Kidney stones have many causes. The most common chemicals found in kidney stones are calcium, oxalate, and uric acid. Significant promoters of kidney stone formation are genetic (aka inherited) factors, dehydration, and low dietary magnesium. Although serum uric acid levels go up in the early adaptation phase of a well-formulated ketogenic diet, this is caused by decreased excretion, not increased production. And after a month or two, the kidneys adapt to maintaining normal uric acid excretion. At Virta, we devote considerable attention to hydration, adequate but not excessive dietary sodium and calcium, and despite plenty of green vegetables, nut, and seeds (dietary sources of magnesium), we supplement magnesium when there are early clinical signs of depletion.

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  1. Avatar
    Jennifer England January 31, 2019 at 5:45 am

    How many people have you monitored for over 6 months to a year? I switched from vegan to keto and ended up with 4 kidney stones (via CAT scan) one of which had to be surgically removed. I had ZERO on a CAT scan done a year ago for another problem.

    Kidney stones form when certain chemicals become concentrated enough in the urine to form crystals so dehydration can contribute but aren’t the cause.

    My urologist said she had seen a dramatic increase in young women with kidney stones on keto and diet not genetics is driving the increase (since our genes haven’t changed in the last 20 years)

    From Harvard Health “Eating too much animal protein, such as red meat, poultry, eggs, and seafood, boosts the level of uric acid and could lead to kidney stones. A high-protein diet also reduces levels of citrate, the chemical in urine that helps prevent stones from forming.” and pointed out that nuts are rich in oxalate (along with Beets, chocolate, spinach, rhubarb, tea) which I ate a lot of.


    1. Virta Health

      We have been following our patients from the clinical trial for over 3 years and we still see kidney stones as a rare occurrence. The reason for that may be due to the fact that a well formulated ketogenic diet is not, in fact, high in protein. It is moderate, meaning that you eat the amount of protein that your body needs. For individuals that are predisposed to calcium oxalate kidney stones, adjustments may be made to increase dietary citrate and reduce dietary oxalate to reduce the risk for more stones.


  2. Avatar

    Jennifer, as stated above, a keto diet is very much not high protein. Also, were you taking ACV or drinking lemon juice while on Keto? I’m truly curious as to if this actually has an affect on kidney stone formation. I was instructed to do this to prevent any stones forming if my protein intake was too high. I was also instructed to go very light on spinach and suplement potassium citrate. I’m curious if this has any affect as I do not want a kidney stone (had one years ago.) Thanks!


  3. Avatar

    I was just diagnosed with 4 kidney stones today, and have never had one before. I started the keto diet last August and lost 40 pounds and feel better than I have in years. (I am 60) I enjoy the keto diet and am concerned that they will tell me that I can’t be on it anymore. I didn’t think that I have been eating too much meat, but do eat a lot of nuts, and love eating peanut butter on a spoon while watching sports or TV. I also eat a lot of eggs sauteed with spinach. I am really bummed and worry that my friends will be telling me, “I told you so” about the keto diet not being healthy.


    1. Virta Health

      It will be important for future diet considerations to know what type of stones you have and then modifications can be made to your diet to avoid those foods that increase the likelihood of stones.


  4. Avatar

    i myself as a doctor has devoloped two kidney stones and have had a ureteral stent placed , and that was 5 weeks from my keto diet begin ,as a doctor i have had the awareness of continuous drinking for the last 3 or 4 years i also pee pretty much frequently all the time
    never had a renal colic before in my life , the only change in that month was my diet , which was pretty much eggs , vegetables , meat and tunfish , therefore find the argument defending the keto diet pretty much pointless , indeed it gives you a pretty good weight loss ratio , but its not worth the experience of a renal colic and i’m qouting medscape here ”Acute renal colic is probably the most excruciatingly painful event a person can endure. Striking without warning, the pain is often described as being worse than childbirth, broken bones, gunshot wounds, burns, or surgery. ”
    its up to you to take the risk though


  5. Avatar

    How rare is rare?


    1. Virta Health

      We don’t have any published data to share on this but it will depend on personal history, fluid intake, etc.


  6. Avatar

    I wonder to some people on keto eat too many nuts and veg high in oxalates , almond flower etc.? The carnivore groups on line don’t seem to talking about kidney stones and by definition they would be on a high protein diet


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