Poor nutrition driving rise in kidney stones—in adults and kids
A recent study in the Journal of the American Society of Nephrology, found that a high intake of fruits, vegetables, nuts and legumes, low-fat dairy products, and whole grains and low intake of sodium, sweetened beverages, and red and processed meats was associated with reduced risk of kidney stones. This study, which analyzed data from more than a quarter million participants, led me to repost a piece I wrote last year. It's just one more argument to make for healthy nutrition. Enjoy the rest of your summer, Dr. Ayala
Kidney stones are becoming more common at an alarming rate, and this is one trend you should absolutely try to avoid.
If you've ever had one, you know they're no fun. In fact, women who've experienced both kidney stones and child labor describe the pain associated with the passage of a stone as comparable in intensity to that of labor (without an epidural), with much less satisfying rewards.
Diet plays an important role in the development of kidney stones, especially in people who are predisposed to the condition. The incidence of stone disease tends to rise during periods of affluence, and many experts have concluded that kidney stone is-at least in part-a nutritional disease.
A recent article by Laurie Tarkan in the New York Times reports on the alarming rise in the incidence of kidney stones not just in adults, but also in children. Tarkan says that kidney stones in kids-once considered rare-are now becoming a fairly common condition and are seen in ever-younger ages. As with other diseases related to poor diet-such as type 2 diabetes and obesity-there's a disturbing shift underway in the age of presentation of the condition.
The article interviews several leading urologists, and explores reasons for the rising incidence (emphasis is mine):
"Though most of the research on kidney stones comes from adult studies, experts believe it can be applied to children. Those studies have found that dietary factors are the leading cause of kidney stones, which are crystallizations of several substances in the urine. Stones form when these substances become too concentrated.
Forty to 65 percent of kidney stones are formed when oxalate, a byproduct of certain foods, binds to calcium in the urine. (Other common types include calcium phosphate stones and uric acid stones.) And the two biggest risk factors for this binding process are not drinking enough fluids and eating too much salt; both increase the amount of calcium and oxalate in the urine.
Excess salt has to be excreted through the kidneys, but salt binds to calcium on its way out, creating a greater concentration of calcium in the urine and the kidneys.
"What we've really seen is an increase in the salt load in children's diet," said Dr. Bruce L. Slaughenhoupt, co-director of pediatric urology and of the pediatric kidney stone clinic at the University of Wisconsin. He and other experts mentioned not just salty chips and French fries, but also processed foods like sandwich meats; canned soups; packaged meals; and even sports drinks like Gatorade, which are so popular among schoolchildren they are now sold in child-friendly juice boxes.
Children also tend not to drink enough water. "They don't want to go to the bathroom at school; they don't have time, so they drink less," said Dr. Alicia Neu, medical director of pediatric nephrology and the pediatric stone clinic at Johns Hopkins Children's Center in Baltimore. Instead, they are likely to drink only once they're thirsty-but that may be too little, too late, especially for children who play sports or are just active.
"Drinking more water is the most important step in the prevention of kidney stones," Dr. Neu said."
Other contributing factors examined in this article are obesity, which experts tie to the formation of kidney stones in children as well as adults, and sugary drinks:
"There is also evidence that sucrose, found in sodas, can also increase risk of stones, as can high-protein weight-loss diets, which are growing in popularity among teenagers."
I'd like to add one more to the list of suspects responsible for the rise in stones: Vitamin C.
High doses of Vitamin C can result in high levels of oxalate (a type of salt) in the urine and therefore increase the risk for kidney stones. Since high doses of Vitamin C are not proven to prevent or treat the common cold, or aid your health in any way, there's no good reason to take them.
By no means am I suggesting that parents should worry about kidney stones and devise special diets to decrease their kids' risk of stones. The experts' dietary advice for avoiding kidney stones consists of guidelines one should already be following for a multitude of health reasons, and is quite simple:
Drink adequate amounts of water. Sugar and high-fructose corn syrup-laden juices and sodas don't count as healthy hydration.
Avoid excess salt and highly processed foods. The diet that promotes kidney stone disease is high in sodium, animal protein and sugar, and low in fiber, vegetable protein and unrefined carbohydrates. Another way to describe this diet is a processed-food diet.
The sport drink industry has tricked us into thinking that we need electrolyte infusions on a regular basis, for recreational sports as well as everyday life. The fact is that as long as people are consuming food, which contains ample amounts of electrolytes (really just salts) there's no need to worry about electrolytes.
And wherever electrolytes are added, sweetener is added too, to mask the taste of the electrolytes. That's a good recipe for stones for those who already are susceptible to stone formation. I've written more about sports drinks here.
Dr. Ayala
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