At the International Kidney Stone Institute, our goal is nothing less than the cure.
For some patients who form stones, diet is the primary control mechanism for stone formation, while for others proper dietary management enhances the role of medications. In most cases, the diets of stone formers reveal excessive intake of foods and low intake of fluids, both modifiable. Stones are associated with excess in the patient's diet, namely of salt and protein. The following are common dietary measures patient may take to reduce stone formation:
The number one thing patients can do to prevent stone formation is to drink more fluids, thereby diluting the urine molecules that cause stones to form. All fluids count, but water is the best choice. To avoid issues related to certain types of water (hard water with high calcium content, softened water with high sodium content), purified bottled water is highly recommended. Patients should strive to urinate more than two liters per day. The urine color should be pale yellow, 24 hours a day. If the urine is too concentrated, crystals can more readily form and then stick together to form stones. Keeping the urine very dilute by drinking extra water every day helps reduce this problem. All fluids (water, coffee, juice, soda) count towards the output goal of two liters per day, but grapefruit juice should be avoided. Note that volume of fluids consumed does not equal volume excreted: those who live and work in hot and/or dry environments will lost fluid through perspiration and must drink enough that the urine volume remains above two liters.
It may seem counterintuitive to patients who form stones, but patients should strive to meet the Recommended Daily Allowance (RDA) for calcium, which ranges from 1000mg to 1200mg per day. Recent evidence suggests that a normal calcium/normal protein diet has a greater protective effect against stones than does a reduced calcium diet. In addition, the body needs dietary calcium to support the skeleton, particularly important for patients whose bones have already been depleted by years of excess calcium excretion. Stone formers should consume two servings of dairy (but no more than two) or other calcium-rich food per day to maintain bone stores of calcium and should avoid calcium supplements in tablet or capsule form. There are rate exceptions to this rule, such as for those patients who form brushite stones, associated with extraordinarily high urine excretion. But, most calcium stone formers should strive to meet the RDA for calcium.
The human body carefully regulates its sodium levels. When excess sodium is excreted in the urine, calcium is also excreted proportionally. In other words, the more sodium taken in and excreted, the more calcium is wasted in the urine. Excess calcium in the urine can lead to new stone formation: Salt in diet ? Salt out in urine ? Calcium out in urine ? Calcium stone risk Patients must reduce dietary sources of sodium, including fast foods, packaged or canned foods and salty snacks. They should beware of "silent sources," such as softened water and sports drinks. Careful attention to food labels is critical; dining in restaurants reduces the patient's control over sodium intake. The goal should be to consume less than two grams (2000 milligrams) of sodium per day. It may be helpful to see a registered dietitian to accomplish this difficult goal. Note: the thiazide diuretics work much less effectively in the presence of excess sodium excretion.
Many people, especially Americans, exceed necessary protein intake, and this is commonly found in patients who form uric acid stones. As a general recommendation, stone patients should limit daily protein intake to 12 ounces per day of beef, poultry, fish and pork. Twelve ounces is equivalent in size to about three decks of cards. This will be sufficient to meet the body's needs. Interestingly, high protein intake is associated not only with uric acid stone, but also with calcium stones. So, this recommendation applies to all patients who form stones.
This is important only for patients who form calcium-oxalate stones. Unfortunately, high oxalate foods - chocolate and nuts -- are some of America's favorites. Oxalates are also high in green leafy vegetables like spinach and collards, in beets, wheat germ, soy and in rhubarb. Black tea is also a high-oxalate product. Oxalate and calcium bind wherever they are found together: in the gut or in urine. So, if high oxalate-containing foods are consumed, eating a high-calcium food at the same time may have a protective effect; if calcium and oxalate bind in the gut, they will be excreted in stool, not in the urine where stones form.