DIET – KIDNEY STONES

The kidney acts as a filter for blood, making urine and removing waste products

from the body. When the stone sits in the kidney, it rarely causes problems, but

when it falls into the urethra, it acts like a dam. As the kidney continues to function

and make urine, pressure builds up behind the stone and causes the kidney to swell.

Here are a few dietary modifications to help you fight Kidney Stones:

Diet recommended for Kidney stones

• Drink more liquids

Drinking 10-12 glasses of liquid each day helps to keep the urine dilute - which

reduces the concentration of stone forming minerals in the urine. At least half of

the liquid should be water; the other liquids could be any beverages you like.

• Reduce the amount of salt you eat

Reducing the salt (sodium) in the diet helps to reduce the amount of calcium in the

urine that in turn reduces the tendency for calcium stone formation. Dietary salt

reduction is best accomplished by not adding salt to your food and by avoiding

those high sodium foods such as processed meats, salty convenience foods

(regular, boxed or canned soups, noodle or rice mixes) and salty snacks.

• Be sure your diet contains adequate amounts of calcium

Several years ago it was believed that dietary calcium should be restricted in

patients with calcium kidney stones. At least two scientific studies now show that

the inclusion of at least two servings of high calcium foods per day in the diet

actually reduces the rate at which calcium-containing kidney stones form. People

who form calcium oxalate stones should include 800 mg of calcium in their diet

every day, not only for kidney stone prevention but also to maintain bone density.

A cup of low-fat milk contains 300 mg of calcium. Other dairy products such as

yogurt are also high in calcium.

• Avoid those foods which can increase the amount of oxalate or uric acid in

the urine

Oxalic acid or oxalate is found mostly in foods from plants. But only a few have

been shown to increase the amount of oxalate in urine. They are rhubarb,

spinach, strawberries, chocolate, wheat bran, nuts, beets, and tea. Avoiding

these foods may help reduce the amount of oxalate in the urine. Eating foods

containing calcium also reduces oxalate in the urine. Calcium binds oxalate in the

digestive tract so it is not excreted into the urine.

• Vitamin C

The body converts vitamin C into oxalate that increases kidney stone formation.

Therefore, if the physician has recommended reducing oxalate in the diet, taking

vitamin C supplements may not be a good idea. Doctors recommend no more than

500 milligrams each day for people who have had kidney stones. A person who

has a tendency to form kidney stones should consult a doctor or dietitian before

taking large doses of vitamins or minerals.

• Sugar and animal protein

It has been found that too much of these may also aggravate the development of

calcium or calcium oxalate stones. Some sugars occur naturally in foods and that

is not a concern. However, people who get kidney stones may benefit from

avoiding packaged foods with large amounts of added sugars, and from reducing

sugars added in food preparation and at the table.

Meats and other animal proteins - such as eggs and fish - contain purines, which

break down into uric acid in the urine. Foods that are especially rich in purines

include organ meats, such as liver. Nondairy animal proteins may also increase the

risk of calcium stones by increasing the excretion of calcium and reducing the

excretion of citrate (citrate prevents kidney stones) into the urine. Therefore,

people who tend to develop kidney stones should avoid eating more protein than

the body needs each day.

• Insoluble 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 that 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.