November, 2004 - Nr. 11
The Prevention of Kidney Stones
by Dr. Paul Jaconello
Doctor Jaconello is the Medical Director of the Jaconello Health Centre for Nutritional and Preventive Medicine
Anyone who has had a kidney stone will tell you how excruciating the pain is as the stone passes down the urinary tract. Anything that can be done to prevent this very unpleasant medical problem would greatly benefit people at risk or those who have experienced the problem.
Seventy percent of kidney stones are made of calcium and oxalate crystals. When the concentration of these substances reaches a certain level, they will crystallize out of solution in the urine to produce gravel and then a fully formed stone. Therefore, the amounts of calcium and oxalates in the urine and as well, the surrounding environment, which determines the ease with which the material comes out of solution, determines the formation of kidney stones.
Therefore, kidney stones can be prevented from occurring by 1) reducing the concentrations of urinary calcium and oxalate and 2) changing the solubility coefficient of these substances to help them stay in solution. These two goals can be achieved by simple and effective nutritional changes.
The following are basic actions that one can take:
- Reduce calcium loss into the urine by:
- Reducing or avoiding intake of coffee, tea, soft drinks, sugar and
alcohol.
All of these substances promote calcium loss in the urine. Medical studies have shown that the high intake of these beverages and foods increases the levels of calcium in the urine. - Reducing the level of protein intake.
Investigators have shown that individuals on high protein diets have higher levels of calcium in the urine than those individuals who are on lower protein diets. Therefore, heavy meat, chicken and egg eaters need to reduce serving sizes and learn how to introduce and eat more vegetarian meals.
These include rhubarb and tea. Although, collards, kale, mustard greens, beet greens, swiss chard, spinach and rapini are high in oxalate, they are also extremely rich in magnesium. Also, the high calcium levels present in these vegetables tend to block the absorption of oxalate in the gut. Hence, avoidance or severe restriction of these nutrition foods may not be necessary.
The daily intake of vitamin B6 in a dose of 10mg to 50 mg has been shown to reduce the manufacture of urinary oxalates thereby, lowering the excretion of this substance in some individuals. Dietary surveys have shown that the typical North American diet contains less than the Recommended Dietary allowance for this important vitamin.
Is calcium restriction necessary?
Patients who have suffered from one kidney stone are often advised to reduce their calcium intake, with the intent of reducing calcium excretion. This action may help, but it is the elevated urinary oxalate that is a greater problem than the elevated urinary calcium in the formation of a stone. In fact, low calcium diets will allow increased levels of oxalate to be absorbed from the intestines as calcium binds oxalate in the gut, thereby reducing its absorption. In addition, low calcium diets may promote loss of calcium from the bone, which increases the risk of osteoporosis, and calcium loss in the urine from bone resorption and thus, may not reduce risk of kidney stones at all! The suggestion is to keep calcium intake around 800 to 1000 mg a day and to ensure an intake of magnesium of 400 to 500 mg a day.
The use of diuretics
Diuretics are drugs that promote fluid loss in the kidneys. They are often prescribed to prevent the recurrence of stones because they reduce urinary calcium excretion and increase urinary magnesium excretion.
However, there are inherent problems with such treatment. Diuretics can induce insufficiencies of potassium and magnesium in the body by increasing their excretion in the urine. These deficiencies can lead to weakness, muscle fatigue, pain and heart irregularities. Very often, potassium supplementation is given by medical practitioners to prevent low blood potassium levels but only rarely is magnesium supplementation advised. Often, chronic magnesium deficiency is overlooked in individuals taking diuretics. These drugs can also promote high blood sugar and high uric acid levels. Also, the use of diuretics is often accompanied by frequent trips to the washroom.
Summary
Renal stone disease has an annual incidence of 7 to 21 cases per 10,000 individuals. The majority of stones (70 to 80%) are composed mainly of calcium oxalate crystals.
A Consensus Panel from the National Institute of Diabetes and Digestive and Kidney Diseases and the Office of Medical Application of Research of the National Institutes of Health in the United States published recommendations for prevention of recurrent kidney stones. They suggested adequate hydration (drinking lots of water), restricting dietary calcium to 1000 mg per day or less and the use of thiazide diuretics to reduce urinary calcium excretion. However, this panel failed to recommend the use of vitamin B6, magnesium supplementation, moderation in protein intake and the avoidance or restriction of refined carbohydrates. They overlooked the beneficial effects of vegetarianism, dietary fibre and avoidance of sugar, caffeine and alcohol.
It is a shame that simple, basic lifestyle choices are often not communicated to the general public so that the occurrence of kidney stones with the attendant suffering and pain could be significantly reduced. In an age of spiraling health costs, such simple and basic measures would do much to lower the dollars consumed with a problem that could easily be reduced in frequency and severity.
Paul Jaconello, M.D.
Doctor Jaconello is the Medical Director of the Jaconello Health Centre for Nutritional and Preventive Medicine.
The Jaconello Health Centre and other health letters
