DIETARY FACTORS AND LIFESTYLE MEASURES USED FOR PREVENTION OF KIDNEY STONES

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FACTORS AND LIFESTYLE MEASURES ARE USED FOR PREVENTION OF KIDNEY

STONE JoAnn Guest

Apr 05, 2007 14:55 PDT

 

 

Patients should take some specific preventive measures to prevent

kidney stones. The most important recommendations for reducing the

risk for calcium stones are increasing fluid intake, restricting

sodium, and reducing protein intake.

 

A lower risk for calcium stones is also associated with potassium

intake. Dietary calcium itself does not appear

to increase the risk for kidney stones.

 

Patients should try to correct

any acidic or alkaline imbalance in the urine so that such stone-

forming substances are more likely to dissolve. Try to avoid stone

recurrence using dietary changes; if such measures fail, other

treatments may be helpful.

 

Fluid Intake

Good voiding habits, particularly frequent urination, are important.

Therefore, of all the preventive recommendations, drinking enough

fluid

is the most important guideline for people with any type of kidney

stones.

 

In general, patients with calcium or uric acid stones should drink

at least 10 full glasses of fluid each day (at least half should be

water).

 

This includes one with each meal and drinking fluids at night, even

if

it means getting up from sleep. Fluid intake should produce at least

two and a half quarts of urine each day.

 

More water (more than a gallon, or 16 8-ounce cups, every day) is

needed to prevent cystine stones, and it must be drunk at regular

intervals throughout the night and day.

 

In all cases, more fluid is needed after exertion and during times

of stress. If fluid intake is sufficient, the urine should be pale

and almost watery, not dark and yellow. Although water is best, it

may vary depending on its source.

 

Other beverages have various positive or negative effects:

 

Variations in water itself may have different impacts. One study

reported that drinking hard tap water increased urinary calcium

concentration by 50% compared to soft bottled water.

 

On the other hand, mineral water containing both calcium and

magnesium may reduce several risk factors for both calcium and uric

acid stone formation.

 

Drinking one-half cup of pure lemon juice (enough to make eight

glasses

of lemonade) every day raises citrate levels in the urine, which

might protect against calcium stones.

 

(While orange juice also increases

citrate levels, it does not lower calcium and it raises oxalate

levels. It is therefore not recommended.)

 

Cola beverages can severely reduce citrate in the urine and should

be avoided.

 

Many soft drinks contain phosphoric acid, which increases the

risk for stones. Some research shows that drinking one quart (less

than three 12-ounce cans) of soda per week may increase a person's

risk of developing stones by 15%.

 

A number of studies have found a risk for stones from drinking

grapefruit juice. In one study, just one 8-ounce cup of grapefruit

juice

per day increased the risk for forming stones by 44%.

 

Fruit juices, particularly apple and cranberry juice, contain

oxalates, although it is unclear whether oxalate-containing foods

pose a risk for calcium oxalate stones. A 2000 study reported

significantly higher

oxalate levels in the urine of patients taking cranberry

supplements, which indicates that people at risk for calcium stones

should avoid cranberry products.

 

Cranberry juice helps prevent urinary tract

infections, however, and so may be helpful for reducing the risk for

struvite stones, although these stones are rare.

 

A study conducted in Finland suggests that the risk of developing

stones decreases with beer consumption. This study found no effects

from coffee, tea, or wine. It should be noted that beer is high in

oxalates.

 

Beer and other alcoholic beverages also contain purines, which may

increase the specific risk for the less common uric acid stones in

susceptible

people.

 

Binge drinking, in any case, increases uric acid and the risk

for stones. No one, of course, is suggesting excessive alcohol

intake for prevention of kidney stones.

 

Low-Salt and Low-Protein Diets

In a long-term 2002 study of men with calcium oxalate stones and

high

levels of urinary calcium, a low-sodium, low-protein diet containing

normal levels of calcium dramatically reduced the recurrence of

stones compared to a diet that was simply low in calcium.

 

Salt Restriction. Because salt intake increases the amount of

calcium in urine, patients with calcium stones should restrict their

sodium intake.

 

Sodium may also elevate levels of urate, the crystalline substance

that can trigger formation of recurrent calcium oxalate stones.

Although the relative contribution of sodium restriction in this and

other studies has not been confirmed, some researchers believe that

restricting sodium

along with increasing fluid intake is the most important dietary

measure for preventing stones.

 

Protein Restriction. Protein increases uric acid, calcium, and

oxalates in the urine and reduces citrate.

 

Diets high in protein, particularly

meat protein, have been consistently associated with kidney stones.

 

(Meat protein has a higher sulfur content and generates more acid

than vegetable protein.)

 

A 2002 trial of those following a high-protein,

low-carbohydrate diet, popularized in such weight-loss regimens as

the

Atkins diet, for example, found dramatically increased levels of

urinary uric acid and calcium after just several weeks.

 

These effects put patients at higher risk not just of kidney stones

but possibly of osteoporosis as well.

 

According to Swiss studies, about a third of

people at risk for calcium stones may have a sensitivity to meat

proteins that cause mild hyperoxaluria.

 

Whether restricting meat protein alone has any protective value

without restricting sodium as well is unknown. Most studies to date

have found no difference in stone development between people with

low and normal meat protein diets over four years.

 

A 2001 study, for example, found no

difference in stone formation in two groups of patients who consumed

beef or plant proteins in equal amounts. A 2000 study reported that

only dramatic reductions in meat protein had any preventive effect

against stone recurrence.

 

Although the precise role of dietary protein in kidney stones needs

further elucidation, it is reasonable for everyone to consume meat

protein in moderation.

 

People with struvite stones, who need to reduce

phosphates in their diets, should also cut down on proteins.

 

Role of Calcium

Calcium from Foods. It has been fairly well established that dietary

calcium is actually protective against many

cases of calcium oxalate stones. Large studies of both men and women

found that those with the highest intake of calcium from foods had a

much lower risk for stones than those who had little calcium in

their diets.

 

And a rigorous five-year 2002 study investigated men with high

urinary levels of calcium who had also had calcium oxalate kidney

stones. Results confirmed that those who followed a diet containing

a

normal amount of calcium but reduced amounts of animal protein and

salt were less likely to have a recurrence of stones than men who

followed a low-calcium regimen only.

 

Dietary calcium may actually bind the oxalate in foods, preventing

it from being absorbed into the blood. It should be further noted

that many people have

calcium stones associated with resorption (the breakdown of bone

that

releases calcium into the bloodstream).

 

Limiting calcium intake in such

people could actually promote further bone loss.

 

Calcium Supplements. Evidence on calcium supplements is mixed,

although

in general many studies suggest that they reduce oxalate levels and

so help prevent calcium oxalate stones. One study suggested that

taking 500 mg of calcium supplements a day regularly may " reprogram "

the intestines to absorb less calcium and so be protective. Experts

generally advise

that calcium supplementation within dosage recommendations, remains

safe.

 

In one study, however,

women who took calcium supplements had a 20% higher risk for stones.

Research indicates that dosages of calcium above 2,000 mg per day

are

clearly associated with the formation of stones.

 

Some experts speculate

that this higher risk may occur because supplements are often taken

in the morning, either without food or with breakfast, which is

typically low in oxalates. Taking supplements with later meals may

not incur the

same risk.

 

Calcium Restriction in Certain Cases. Some calcium stone patients

who have supersaturation of calcium in the urine and who are not at

risk for bone loss may need to restrict calcium, but more studies

are needed to

define this group precisely. Certainly, children with hypercalciuria

should not restrict calcium, since this could harm bone growth.

 

 

Fiber-Rich Foods and their Compounds

Fiber may be beneficial for people with kidney stones. In addition,

some fiber-rich foods may contain compounds that help protect

against kidney stones.

 

A wide variety of high-fiber plant foods contain a compound

called " phytate " (also called inositol hexaphosphate, InsP6, or

IP6),

which appears to help " prevent crystallization " of calcium salts,

both oxalate and phosphate.

 

Phytate is found in legumes and wheat and rice bran.

 

(Soybeans are also rich in phytate but they are also very high in

oxalates, so the overall effects of soy on kidney stones are not

clear.)

 

Fish Oil

Some evidence suggests that omega-3 fatty acids, which are found in

certain oily fish, may have properties that reduce the risk for

calcium

stones. Such fatty acids reduce factors that produce inflammation

and

which may increase the risk for stone production.

 

Omega-3 fatty acids

can be obtained in supplements.

 

 

Purine Restriction in People at Risk for Uric Acid Stones

 

A high intake of purines can increase the amount of uric acid in the

urine, so those at risk for uric acid stones should reduce their

intake

of foods that contain purines.

 

They include beer and other alcoholic

beverages, anchovies, yeast, organ meats (e.g., liver,

kidneys),mushrooms, cauliflower, and poultry.

 

Oxalate Restriction in Hyperoxaluria

 

Most people with calcium oxalate stones should not avoid oxalate-

rich foods unless the physician specifically recommends a

restrictive diet.

 

Oxalate " binds " with calcium in the intestine, which may

actually " reduce " calcium absorption.

 

Some studies, in fact, indicate that eating foods containing

oxalates and calcium together may " reduce " the risk of stones.

 

Most of the foods that contain oxalates are very important for good

health.

 

Restricting oxalates may be particularly harmful in people with

bowel disorders marked by malabsorption.

 

Foods high in oxalic acid include beets, soy, beet tops, black tea,

chenopodium, chocolate, cocoa, dried figs, ground pepper, lamb, lime

peel, nuts, parsley, poppy seeds, purslane, rhubarb, sorrel,

spinach,

and Swiss chard.

 

Foods containing moderate amounts of oxalates include beans (green

and

wax), blackberries, blueberries, carrots, celery, coffee (roasted),

concord grapes, currants, dandelion greens, endive, gooseberries,

lemon

peel, okra, green onions, oranges, green peppers, black raspberries,

strawberries, and sweet potatoes.

 

Vitamins in Hyperoxaluria

Vitamin C Restriction. Ascorbic acid (vitamin C) may convert to

oxalates, and people with hyperoxaluria should avoid vitamin C

supplements. (A high intake of vitamin C does not appear to increase

the

risk of stone formation in people with no risk factors for stones.)

 

Vitamin B6. Vitamin B6, or pyridoxine, is used to treat people with

hyperoxaluria when dietary reduction of oxalates and calcium

supplements

is not effective in preventing stones.

 

It is particularly beneficial for the inherited disorder, type I

primary

hyperoxaluria. Patients should not try to self-medicate with vitamin

B6.

Very high doses (500 to 2,000 mg daily over long periods) can cause

nerve damage with loss of balance and numbness in the feet and

hands.

Food sources of vitamin B6 include meats, oily fish, poultry, whole

grains, dried fortified cereals, soybeans, avocados, baked potatoes

with

skins, watermelon, plantains, bananas, peanuts, and brewer's yeast.

Citrate salts may also be important for people with excessive levels

of

oxalates.

 

Stress Management Techniques

Because of an association between stress and kidney stones,

relaxation

and stress management techniques may also be beneficial.

 

http://www.umm.edu/patiented/articles/dietary_factors_lifestyle_measu

res_used_prevention_of_kidney_stones_000081_8.htm

 

 

JoAnn Guest

mrsjo-

www.geocities.com/mrsjoguest/