Tips For Kidney Stones Prevention
Kidney stones can often be avoided with some precautions and minor adjustments to current behaviors. Everyone in the emergency room with a stone loudly proclaims "I will do anything to avoid another stone." In reality, very few people will stay on a prophylactic treatment program for many years.
Kidneys filter the blood to remove excess mineral salts and other soluble (dissolvable) wastes. The kidneys also produce the urine that dissolves these wastes and excretes them through the urinary tract. Kidney stones form when the urine becomes so saturated with a certain mineral that no more of it can dissolve into the urine (like trying to dissolve too much sugar in your iced tea). The undissolved portion of the mineral forms crystals that then clump together and grow into hard stones.
- 1Drink a lot of fluids
This is the most important preventive measure. Proper hydration helps prevent the urine from becoming concentrated with crystals, which can lead to stone formation; and reduces the risk for urinary tract infections, which may lessen the risk for struvite stones. Urine color can indicate the level of concentration: dark or bright yellow urine indicates highly concentrated urine; pale or colorless urine indicates dilute urine.
What fluids are the best?
Researchers found that beverage type may have an effect on stone formation. Black tea should be limited because black tea is a high-oxalate beverage. In the Nurses' Health Study1, those who drank one daily 8 ounce glass of grapefruit juice had a 44% increased risk of a stone formation in the 8-year period, while the risk was decreased by 8% to 10% for each daily 8 ounce serving of coffee (both caffeinated and non-caffeinated), tea, or wine. A prospective study2 had similar conclusions for men, additionally showing that beer had a protective effect and apple juice increased the risk of kidney stones.
In summary, stone formers should drink more water and avoid excess caffeine, black tea, and grapefruit and apple juices. Water is the best beverage. Lemonade is often recommended, as it supplies dietary citrate, a stone inhibitor and pH buffer when excreted later in the urine. - 2Diet containing normal or increased
amounts of calcium
Eat normal amounts of dairy products and other calcium-rich foods.
Since most kidney stones are calcium stones, the conventional wisdom has been to limit calcium intake to prevent recurrence. Research has proved this wrong6, however. Evidence shows that this approach actually leads to more stones. In fact, researchers have found that women with a high calcium intake are less likely to develop kidney stones than are women who consume less calcium3. A 5-year randomized clinical trial6 of men with a history of calcium oxalate stones found that a normal calcium, decreased sodium, and decreased animal protein diet was more effective for reducing stone events than was a restricted calcium diet. Why? Dietary calcium binds with oxalates in the gastrointestinal tract so that oxalates can't be absorbed from the intestine and excreted by the kidney to form stones. Interestingly, however, supplemental rather than dietary calcium was found to increase the risk of stones. The explanation may be that supplements are often ingested without food or after a meal low in oxalate.
An exception to this rule occurs when an individual absorbs too much dietary calcium from the intestine. In such a circumstance, follow your doctor dietary advice. - 3Limit foods high in oxalate
If you tend to form calcium oxalate stones, you may consider restricting foods rich in oxalates. Foods that cause significant increase in urinary oxalate excretion are: spinach, rhubarb, beets, nuts, chocolate, tea, wheat bran, and strawberries7. Complete oxalate list can be found on the Web site of the Oxalosis and Hyperoxaluria Foundation. - 4Reduce sodium intake
Reducing sodium in the diet appears to reduce the amount of calcium excreted in the urine. Because calcium and sodium compete for reabsorption in the renal tubules, excess sodium intake and consequent excretion result in loss of calcium in the urine. High-sodium diets are associated with greater calcium excretion in the urine. - 5Reduce meat (animal protein) consumption
High protein intake is an accepted risk factor for kidney stone8. A diet high in animal protein affects certain minerals in the urine that may promote the formation of kidney stones. Therefore, people who tend to develop kidney stones should avoid eating more protein than the body needs each day.
An overall diet low in salt and very low in animal protein can greatly reduce your chance of developing kidney stones. - 6 Lose extra pounds
There is a relationship between weight, body mass index and risk of calcium oxalate stone formation. Researchers found that "the prevalence of stone disease history and the incidence of stone disease were directly associated with weight and body mass index. However, the magnitude of the associations was consistently greater among women". The value of weight loss for stone prevention has not been proven, but given the benefits of weight loss for general health, it is certainly worth mentioning to overweight people with kidney stones. - 7Insoluble fiber
Fiber is the indigestible part of plants. There are two types of fiber: soluble (dissolves in water) and insoluble. Both provide important functions in the body, but it is insoluble fiber (found in wheat, rye, barley, and rice) that may help to reduce calcium in the urine. It combines with calcium in the intestines, so the calcium is excreted with the stool instead of through the kidneys. Insoluble fiber also speeds up movement of substances through the intestine, so there will be less time for calcium to be absorbed. - 8Avoid excessive use of vitamin D
Vitamin D is a fat soluble vitamin. When taken in excess amounts, it cannot be removed from the body as easily as water soluble vitamins. If excessive Vitamin D is converted to its active form (calcitriol), it can lead to too much calcium in the blood or hypercalcemia. Hypercalcemia caused by excess Vitamin D can lead to many complications including kidney stones and kidney failure.
Sources & References
- 1. Curhan GC, Willett WC, Speizer FE, Stampfer MJ. Beverage use and risk for kidney stones in women. Ann Intern Med. 1998 Apr 1;128(7):534-40. PubMed
- 2. Curhan GC, Willett WC, Rimm EB, Spiegelman D, Stampfer MJ. Prospective study of beverage use and the risk of kidney stones. Am J Epidemiol. 1996 Feb 1;143(3):240-7.PubMed
- 3. Curhan GC, Willett WC, Speizer FE, Spiegelman D, Stampfer MJ. Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women. Ann Intern Med. 1997 Apr 1;126(7):497-504. PubMed
- 4. Dietary Changes to Prevent and Reduce Stone Formation MedScape
- 5. Kidney Stone Diet gicare.com
- 6. Borghi L, Schianchi T, Meschi T, Guerra A, Allegri F, Maggiore U, Novarini A. Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria. N Engl J Med. 2002 Jan 10;346(2):77-84. PubMed
- 7. Massey LK, Roman-Smith H, Sutton RA. Effect of dietary oxalate and calcium on urinary oxalate and risk of formation of calcium oxalate kidney stones. J Am Diet Assoc. 1993 Aug;93(8):901-6. PubMed
- 8. Nguyen QV, Ka"lin A, Drouve U, Casez JP, Jaeger P. Sensitivity to meat protein intake and hyperoxaluria in idiopathic calcium stone formers. Kidney Int. 2001 Jun;59(6):2273-81. PubMed