Diet & Kidney Stones

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Diet Could Prevent Kidney Stones

 

By JANET McCONNAUGHEY

..c The Associated Press

 

 

A diet low in salt and meat can dramatically reduce the risk of

kidney stones, according to an Italian study that could spell the end

for the low-calcium diet that doctors have been recommending for

years.

 

About 10 percent of the U.S. population - and a much larger

percentage of men, who make up 80 percent of sufferers - will have at

least one kidney stone sometime in their lives, and it can be

excruciatingly painful. Most stones can be excreted, but in about 15

percent of cases, surgery or shockwave treatment to pulverize the

stones is needed.

 

Many doctors have told such patients to cut down on calcium because

most kidney stones are made of a calcium compound. But recent studies

have suggested that such a diet might not prevent kidney stones after

all and may even promote them - along with osteoporosis.

 

The new study ``dispelled a myth that a low-calcium diet is important

in preventing kidney stones,'' said Dr. David A. Bushinsky, a kidney

specialist at the University of Rochester.

 

William Keane, president of the National Kidney Foundation, said he

is sure the new diet ``will become the gold standard.''

 

The University of Parma study randomly assigned either a low-calcium

diet or a diet low in salt and extremely low in protein to men who

had had at least one kidney stone. Sixty men were assigned to each

diet.

 

Twenty-three men on the low-calcium diet had another kidney stone

within five years, compared with 12 on the low-salt, low-protein

diet, Dr. Loris Borghi wrote in Thursday's New England Journal of

Medicine.

 

A co-author, Dr. Umberto Maggiore, explained that people on a low-

calcium diet excrete less calcium in their urine but more of the

other substance - oxalate - that combines with calcium to form most

kidney stones.

 

In addition, salt and one protein common in meat lead to more calcium

in the urine, which in turn contributes to the formation of kidney

stones, Bushinsky said.

 

He said he has not prescribed a low-calcium diet in a decade because

of evidence that it leaches calcium from the bones, making them

weaker. Women were not included in the Italian study because of the

danger of osteoporosis.

 

The low-salt, low-protein diet allowed 2,900 milligrams of salt per

day; 2,400 is the maximum recommended by the American Heart

Association. But people were allowed only about three-quarters of an

ounce of meat per day, with just over an ounce of cheese or other

dairy protein.

 

The American Foundation for Urologic Disease does not mention a low-

calcium diet on its Web page about kidney stones, but does say a

doctor may suggest a low-meat, low-salt diet. The National Kidney

Foundation's Web page says a doctor may suggest either diet,

depending on test results.

 

Borghi's study is the first direct comparison of the two diets, said

Dr. Julie R. Ingelfinger, the journal's deputy editor. She wrote that

the diet has been proved effective only for men in Italy's Parma

region, but is worth trying ``for anyone who has had a stone or who

has witnessed the suffering of a friend or family member with a

stone.''

 

Maggiore said the diet would be equally effective in any country, but

he noted that it might be harder to get Americans to stick to it

because meat makes up such a great part of the U.S. diet.

 

Health care for kidney stones added up to $1.8 billion in 1993,

according to the National Institute of Diabetes and Digestive and

Kidney Diseases. Drinking 10 to 12 big glasses of water during the

day can keep stones from forming and push out those smaller than a

pea.

 

On the Net:

 

National Kidney Foundation:

http://www.kidney.org/general/atoz/content/kstones.html

 

American Foundation for Urologic Disease:

http://www.afud.org/conditions/ksafter.html

 

AP-NY-01-09-02 1742EST

 

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