Curbing Kidney Stones

Why plenty of water and a proper diet can reduce the risk of a painful recurrence

by Beverly Burmeier

October 2010


Got a birthday, anniversary or other reason to celebrate? If a steak dinner is your favorite way to splurge, there’s a good reason to reconsider: Excessive dietary protein, especially from animal sources, could put you at higher risk for kidney stones.

The number of people affected by kidney stones has increased tenfold during the past century, with an apparent correlating rise in the consumption of animal proteins. What does that mean for millions of Americans embracing low-carb, high-protein diets? “Consuming more protein than you need for nutritional requirements, which most Americans do, causes an increase in urinary calcium, which could increase risk for kidney stones,” explains Linda Massey, PhD, RD, professor of human nutrition at Washington State University Spokane.

In most people, natural chemicals in the body prevent crystals from forming in the urine. For others, crystals form hard masses, most commonly from calcium and oxalate. Some stones remain “silent” and don’t cause symptoms, but if a large stone moves, it can cause excruciating pain in the back or lower abdomen. Chronic irritation or blockage of the urinary tract could lead to kidney damage.

Stones are most likely to develop in people between the ages of 30 and 50. According to the National Kidney Foundation (www.kidney.org), one in seven American men will experience a kidney stone over the course of his lifetime. A woman’s chance of stone development is only one-third of a man’s. However, a woman’s risk increases after her fortieth birthday, when decreasing estrogen supplies may result in a urinary calcium imbalance that can cause stones to form. Having a stone is bad enough; what’s worse is that one attack makes you 30% more likely to have another.

Raising the Risk

There is no one reason why some people develop kidney stones and others don’t. Abbey Gaske, MD, a Los Angeles urologist, notes that nutritional, genetic and lifestyle factors all contribute. “Everything has to do with balance,” she says. “One food component affects the absorption of others and if you restrict or overindulge in one thing, you throw off the balance of another.”

If a man’s mother had kidney stones his risk increases as much as 2.5 times. “A genetic tendency for high calcium content in urine or inherited abnormalities that limit the body’s ability to properly break things down could increase susceptibility,” says Gaske.

Research shows that men who weigh more than 220 pounds have a 44% greater chance of developing kidney stones than those weighing less than 150 pounds. Weight gain in women is problematic, too, with a 39% increased risk for those who gained more than 35 pounds after age 21 compared to those who maintained their weight.

A sedentary lifestyle—whether from being overweight or bedridden, or because of one’s occupation—can be a factor in stone development. In addition, certain medications for hypertension, diabetes and intestinal disorders can affect urine balance and thus increase risk.

Stopping Stones

The best way to prevent kidney stones is by drinking lots of water, a minimum of six to eight glasses per day. Anecdotal evidence points to increased stone formation in summer months and in the South—sometimes called the “stone belt”—because dehydration is likelier in warm climates.

Nighttime counts, too: Stones often form when urine is most concentrated, so getting up to drink a glass of water can reduce risk. Drinking lemon juice (in the form of lemonade) has been shown to decrease the incidence of recurrent stones. (In spite of its reputation as a preventative measure, cranberry juice has not been proven to be helpful in stopping stone formation.)

Another way to reduce stone formation is by cutting your intake of salt, which can cause too much calcium to remain in the urine. Besides avoiding the salt shaker and salty snacks, reduce consumption of all processed foods, many of which are high in sodium (luncheon meats and canned soups are among the worst offenders).

Excess sodium can drive up blood pressure as well as kidney stone risk. The DASH (Dietary Approaches to Stop Hypertension) eating plan, which emphasizes fresh produce and whole foods, is designed to reduce pressure; it may also lower the risk of stone formation (Journal of the American Society of Nephrology 10/09).

Among the foods featured by the DASH diet are legumes, the bean and pea family. These foods contain phylates, which appear to protect kidneys by keeping calcium in the bones, where it belongs, and out of the urine. However, some normally healthy foods may promote stone formation because of their oxalate content; they include beets, chard, chocolate, okra, peanuts, soybeans, spinach, rhubarb and wheat germ. As counterintuitive as it seems, low-fat dairy—another DASH diet item—helps reduce kidney stone risk by binding up oxalate before it can combine with calcium. (To learn more, see www.dashdiet.org.)

One way to balance calcium levels is by consuming more magnesium, which helps keep calcium from joining to oxalate. Increased magnesium intake has been associated with reduced stone risk (Journal of the American Society of Nephrology 12/04). Complementary practitioners often recommend combining magnesium with vitamin B6 to prevent stone development. (If you are prone to kidney stones, consult a health professional before making dietary changes.)

No one who has suffered kidney stone pain would ever want to experience that again. Drinking plenty of water and making dietary adjustments may help keep a recurrence at bay.

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