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
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.