Does Your Healthy Diet Promote Kidney Stones?

By Pete Williams

Kidney stone diet: protein powder, berries, chocolate

If you’re a nutrition-conscious, water-chugging, avid recreational athlete, you probably think you’re immune from kidney stones.

So did I, at least until I was brought to my knees New Year’s Day by the worst pain of my life – a kidney stone that turned out to be 1 cm in diameter – about the size of a 3D dime.

After three weeks and two surgeries, I’m stone free. Like any stone sufferer, I’m willing to do anything to avoid another stone, especially considering 50 percent of us will have another stone within five to 10 years.

Dietary changes are a must, though there’s no one-size-fits-all game plan. Some people, regardless of genetics, are more prone to becoming “stone formers.”

“You and I can follow the same diet and you’ll develop stones and I won’t,” says James Borin, a urologist at the University of Maryland medical center in Baltimore.

More than a half million people annually are hospitalized annually with kidney stones, a pain often compared to childbirth. The number of kidney stone episodes is on the rise. Male victims once outnumbered women 3-to-1, but now the ratio has closed to almost 50/50.

Kidney stones form when there is not enough fluid in the body to flush out waste. Your kidneys, along with the ureters and bladder, serve as your body’s plumbing. When there’s too much waste and not enough fluid, it’s as if hair is clogging the drain. Some stones pass on their own, but for others it takes a plumber – a urologist – to remove the stone.

More than three-quarters of kidney stones are calcium oxalate. Oxalate, a waste product of metabolism, combines with the calcium you eat to make the crystals that form the stone.

You might think high-oxalate foods would be things that are bad for you anyway, but that’s hardly the case. The bad list includes chocolate and cola drinks, but also spinach, nuts, sweet potatoes, and most berries.

Do you like salty foods? Those too are dangerous.  “We’re salt-loving creatures,” Borin says. “The kidneys will suck that sodium up and exchange it for calcium, which gets into the urine.”

Calcium is the most debated area of kidney stone research since it’s believed that both too much and too little calcium can contribute to stone formation.

At least there’s protein, right? Nope. Protein is a hot spot for kidney stones since animal protein, whether from red meat, chicken, fish, or elsewhere, is metabolized to oxalate. A high-protein diet, therefore, increases risk for stones.

Like to drink? Alcohol itself does not contribute to stone formation. But it makes you pass more urine and lead to dehydration.

The more I read about kidney stones, it seems the only way to prevent them is to become a vegan – a vegan who does not eat nuts and is allowed only a few fruits and vegetables.

“Fluid intake is critical,” says David Goldfarb, a New York nephrologist and member of the American Society of Nephrology. “If you ate a lot of spinach and drank a lot of water, the fluid trumps everything else.”

Unlike urologists, whose specialty includes the surgical removal of kidney stones, nephrologists are kidney specialists who typically stay out of the operating room. A urologist gets rid of the stone, but a nephrologist shows the patient how to avoid becoming a urologist’s repeat customer.

It starts with the patient filling a jug with urine for 24 hours. A Chicago company provides a kit, including a special FedEx package. From there, the nephrologist can perform a urinalysis and determine what dietary changes should be made.

I have yet to undergo this process. But I’ve spent a lot of time pondering what aspects of my diet could have caused the stone.

At first I was puzzled. I don’t drink coffee, tea, or soda, nothing but water and an occasional glass of wine. I have no family history of stones, and eat a balanced diet of lean proteins, fruits, and vegetables. My dairy/calcium consumption, if anything, is low.

What could go wrong? Plenty, as it turns out, and I have lined up some suspects:

SPINACH: I eat a lot of spinach. I use it as the base of my salad and saute it in olive oil several nights a week to go with chicken or fish. Have I amped up my consumption of spinach over the last year or two? I’m not sure that I have.

NUTS: I once ate unsalted nuts like candy, figuring they were a healthy snack. But several years ago I shifted to snacking more on fruit. That rules out nuts. But fruit?

BERRIES: As with spinach, I didn’t realize there was a downside to eating berries. I eat a lot of blueberries, blackberries, strawberries, and raspberries. I also consume a fair amount of fruit-on-the-bottom yogurt. Like spinach, berries are high in oxalate. Over the last year, I’ve gotten into the habit of purchasing frozen berries and substituting them for desserts. So it looks like berries were a contributing factor to my stone.

WATER: When you drink only water, you must drink enough, right? Not necessarily. The guideline is that you must drink enough to produce at least 2,000 ml of water a day – enough to fill a two-liter bottle. Of course, drinking that much does not mean you produce that much urine, especially if you’re a Florida-based triathlete who sweats out a lot of water.

Goldfarb recommends drinking three liters of water a day, which should produce two and a half liters of urine. (He has patients use plastic urinal bottles to keep track.)

“It’s easy to say, ‘drink more water,’ but that doesn’t mean anything,” he says. “You have to be quantitative about it, not every day, but on a regular basis.”

One way to determine if you’re drinking enough water is to examine the color of your urine. It should be clear.

Bottom line: I’m not drinking enough water.

CHOCOLATE: Time to come clean. Chocolate is my Kryptonite. And I’ve been known on occasion to raid my wife’s baking cabinet, where she keeps the chocolate chips. I do so at night, compounding the problem.

ENERGY BARS: What’s wrong with energy bars? Nothing other than the chocolate, nuts, and high-protein content. I average two a day, at least one too many.

PROTEIN: The U.S. recommended daily allowance for protein is 0.8 grams of protein per kilogram of body weight. As a 167-pound endurance athlete, I can bump that to 1.2 grams per kilo or 91 grams of protein per day.

For years, I drank meal replacement powder shakes after workouts. They tend to be fairly balanced between carbs and proteins, containing roughly 30 grams of protein. I probably managed to stay under 91 grams of protein daily, even with my regular consumption of fish and chicken for lunch and dinner.

Midway through 2009, I stopped buying meal replacement powders and began purchasing various whey protein products, chocolate-flavored, of course. To get the same amount of powder in my shakes as an MRP packet, I dumped in four scoops of whey, which comes to 108 grams. Even worse, I threw a fifth scoop into my breakfast oatmeal.

Even though I knew that probably was too much, I didn’t realize the danger of excess protein. That, combined with increased consumption of berries, an existing diet high in spinach and chocolate, and inadequate water formed the perform storm – or stone.

“It could be something as simple as your body was able to keep up with this for some time but something changed and it pushed you over the edge,” Borin said. “The good news is that some behavioral modification goes a long way.”

Fortunately there are plenty of healthy foods that don’t promote kidney stones. They include lettuce, mushrooms, onions, avocado, cauliflower, oil and vinegar dressing, citrus fruit, watermelon, small deck-of-cards size portions of chicken and fish, peas, wild rice, and tomatoes (but not tomato sauce).

According to the book No More Kidney Stones, the definitive resource on the topic, there are plenty of foods that are not nutritious but at least they have low oxalate content. These include white flour items such as bagels, English muffins and rolls; syrup, pancakes, waffles and French toast.

I think I’ll stick with oatmeal, which thankfully makes the cut.

My upcoming tests with the nephrologist will paint a clearer picture of what I need to change. For now, I know that what I thought was a healthy diet was almost tailor made for kidney stones.


Filed under Nutrition, Training

17 responses to “Does Your Healthy Diet Promote Kidney Stones?

  1. Dan

    A few years ago I thought I had kidney stones. After at trip to the emergency room, modification of my diet, and many painful episodes of what I thought were kidney stones, I found out I had an inguinal hernia. In case someone has symptoms, there “could” be other possibilities as well.

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  3. Vanish

    Thank you for the article. I am 2 yrs post Gastric Bypass surgery. I lost 150lbs and at and have maintained my goal weight for over a year. I didn’t know that my Choc protein powder, choc soy milk shakes each day were making me form kidney stones. My choc protein bars, berries, raw nuts, bran cereal etc! Was in the ER 10 days ago and then surgery. I am loaded with many stones! Now I have to rethink my entire food plan. Protein is mandatory for me because of the Bypass surgery. I have the food lists, but find them to be incomplete. Is there a good source out there to look up foods not listed? What about Vanilla Whey Protein? How do I shop at the store and read labels correctly and purchase the correct foods. I will be doing blood work and the 24 hr urine collection in the next month.

    • You have my sympathies. I think what I’ve learned from examining foods over the last year for how they relate to kidney stones…is that there’s no easy answer and urologists don’t put much effort into preventing stones. Nephrologists are supposed to, but all my guy did was hand me a list of foods printed off the Internet. Thanks. Getting a 24-hour urine done will provide some specifics in terms of what specific foods you’ve getting too much of. For me it’s still too much animal protein, which is good because I didn’t want to give up nuts, berries, and other things that are actually good for you! If you read the book No More Kidney Stones, you might come away thinking you can’t eat much of anything – healthy or not. I wish I had more answers. It’s amazing there’s not more research and expertise in this area.

    • posta

      go vegan with lots of salads, fresh jiuces and smoothies and you don’t need to worry about bypass

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  5. jc

    I could have written your post! Had first kidney stone when I was 26. Changed my diet then and over the years I thought I was eating healhy.

    Lot of berries, nuts,chocolate whey powder in my oatmeal, tomato sauce, beans, swiss chard…you get the idea. Last month I had another kidney stone attack. Passed the stone but CT Scan found 3 more stones…too big to pass.

    scheduled for lithotripsy proceedure soon. Drinking lots…of water and cut out high oxlate foods.

    So much for eating healthy.


    • Wow, JC. I feel your pain.

      I’m 18 months without a stone and the last ultrasound I had did not show any forming. But I pay attention to everything.

      Tests all last year showed I still was eating too much animal protein, so I’ve cut way back, trying to stick with a vegan-plus-fish routine. We’ll see what works. Good luck.


      • Cate

        Hi. I was very interested to read your article. I too had a kidney stone and it was only when I read the list of high oxalate foods that I realised that my ‘healthy’ eating had caused me to by quite ill. It’s difficult to know what to eat any more. No more bran, soya products, almonds, peanut butter, tomatoes and berries! I don’t think other people realise how much these foods are actually bad for you. More awareness of kidney stones is needed.

  6. Robyn Toronto

    Having kidney stones twice, my doctor suggested that I start drinking cranberry juice daily every morning, as cranberries are supposed to help prevent the formation of kidney stones. Well, I am not a big fan of juice, so thought I would give the Cranberry Concentrate from Lady Soma Products a try. Its a cranberry supplement with Vitamin C in it. I am very pleased with the product, and it has totally helped!

    Cranberry juice tastes awful and is mostly sugar, and the antibiotics give me stomachaches. Absolutely no side effects for this Lady Soma Cranberry Supplement. Don’t know now what I’d do without it.

    • Thanks for sharing, Robyn. There seems to be surprisingly little research/information on dietary changes out there, so all input is appreciated. Let’s hope this time works for you!

  7. Nathan

    Thanks for the great article. I’m passing a 4-5mm stone right now. It’s bouncing around my bladder as I type this. I will closely examine my food intake, and see where I can improve. I’d like to never experience this kind of excruciating pain ever again.

    Thank you.

  8. Eugene Dinges

    Unfortunately, when you walk into your local health food store to purchase a whey protein powder, you will probably be expecting a qualified sales person who knows all about the products on the shelf. What you will actually – most likely – encounter is a teenager who doesn’t know the first thing about body building, much less the products on the shelf in the store where he or she works. They are just there for the minimum wage paycheck. Even if the sales person is qualified to answer your questions, they represent their company – not you – and will suggest the product that nets them the highest profit, instead of the product that is going to net you the most benefit. ^

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  9. Tony

    Thank your information is very useful, very important food for preventing and treatment kidney stones.

  10. Kat

    I’m a kidney stone sufferer and vegan. I think most people have a misconception about healthy foods being unhealthy. It’s not that high oxalate foods are unhealthy. Most people can eat them with no issues. The problem lies in the gut and how stone producers have a faulty digestive system that allows oxalates to enter the body instead of being eliminated. The oxalates aren’t binding with calcium so there is not that protective mechanism in place to get rid of them. I have also read that antibiotic use may play a big part in messing up our gut to allow this to take place. I was on an antibiotic program for 4 years to treat another unrelated health issue which did clear up but now I have stones. There are underlying reasons so we shouldn’t blame it on healthy food. Until there is a cure for this, stone producers MUST resort to low oxalate foods because our systems can’t deal with a high level of oxalates.

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