By Pete Williams
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.